From: Kees Cook <[email protected]>
Having a stable wchan means the process must be blocked and for it to
stay that way while performing stack unwinding.
Suggested-by: Peter Zijlstra <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
---
arch/alpha/include/asm/processor.h | 2 +-
arch/alpha/kernel/process.c | 5 ++---
arch/arc/include/asm/processor.h | 2 +-
arch/arc/kernel/stacktrace.c | 4 ++--
arch/arm/include/asm/processor.h | 2 +-
arch/arm/kernel/process.c | 4 +---
arch/arm64/include/asm/processor.h | 2 +-
arch/arm64/kernel/process.c | 4 +---
arch/csky/include/asm/processor.h | 2 +-
arch/csky/kernel/stacktrace.c | 5 ++---
arch/h8300/include/asm/processor.h | 2 +-
arch/h8300/kernel/process.c | 5 +----
arch/hexagon/include/asm/processor.h | 2 +-
arch/hexagon/kernel/process.c | 4 +---
arch/ia64/include/asm/processor.h | 2 +-
arch/ia64/kernel/process.c | 5 +----
arch/m68k/include/asm/processor.h | 2 +-
arch/m68k/kernel/process.c | 4 +---
arch/microblaze/include/asm/processor.h | 2 +-
arch/microblaze/kernel/process.c | 2 +-
arch/mips/include/asm/processor.h | 2 +-
arch/mips/kernel/process.c | 8 +++-----
arch/nds32/include/asm/processor.h | 2 +-
arch/nds32/kernel/process.c | 7 +------
arch/nios2/include/asm/processor.h | 2 +-
arch/nios2/kernel/process.c | 5 +----
arch/openrisc/include/asm/processor.h | 2 +-
arch/openrisc/kernel/process.c | 2 +-
arch/parisc/include/asm/processor.h | 2 +-
arch/parisc/kernel/process.c | 5 +----
arch/powerpc/include/asm/processor.h | 2 +-
arch/powerpc/kernel/process.c | 9 +++------
arch/riscv/include/asm/processor.h | 2 +-
arch/riscv/kernel/stacktrace.c | 12 +++++-------
arch/s390/include/asm/processor.h | 2 +-
arch/s390/kernel/process.c | 4 ++--
arch/sh/include/asm/processor_32.h | 2 +-
arch/sh/kernel/process_32.c | 5 +----
arch/sparc/include/asm/processor_32.h | 2 +-
arch/sparc/include/asm/processor_64.h | 2 +-
arch/sparc/kernel/process_32.c | 5 +----
arch/sparc/kernel/process_64.c | 5 +----
arch/um/include/asm/processor-generic.h | 2 +-
arch/um/kernel/process.c | 5 +----
arch/x86/include/asm/processor.h | 2 +-
arch/x86/kernel/process.c | 5 +----
arch/xtensa/include/asm/processor.h | 2 +-
arch/xtensa/kernel/process.c | 5 +----
include/linux/sched.h | 1 +
kernel/sched/core.c | 19 +++++++++++++++++++
50 files changed, 80 insertions(+), 112 deletions(-)
--- a/arch/alpha/include/asm/processor.h
+++ b/arch/alpha/include/asm/processor.h
@@ -42,7 +42,7 @@ extern void start_thread(struct pt_regs
struct task_struct;
extern void release_thread(struct task_struct *);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -376,12 +376,11 @@ thread_saved_pc(struct task_struct *t)
}
unsigned long
-get_wchan(struct task_struct *p)
+__get_wchan(struct task_struct *p)
{
unsigned long schedule_frame;
unsigned long pc;
- if (!p || p == current || task_is_running(p))
- return 0;
+
/*
* This one depends on the frame size of schedule(). Do a
* "disass schedule" in gdb to find the frame size. Also, the
--- a/arch/arc/include/asm/processor.h
+++ b/arch/arc/include/asm/processor.h
@@ -70,7 +70,7 @@ struct task_struct;
extern void start_thread(struct pt_regs * regs, unsigned long pc,
unsigned long usp);
-extern unsigned int get_wchan(struct task_struct *p);
+extern unsigned int __get_wchan(struct task_struct *p);
#endif /* !__ASSEMBLY__ */
--- a/arch/arc/kernel/stacktrace.c
+++ b/arch/arc/kernel/stacktrace.c
@@ -15,7 +15,7 @@
* = specifics of data structs where trace is saved(CONFIG_STACKTRACE etc)
*
* vineetg: March 2009
- * -Implemented correct versions of thread_saved_pc() and get_wchan()
+ * -Implemented correct versions of thread_saved_pc() and __get_wchan()
*
* rajeshwarr: 2008
* -Initial implementation
@@ -248,7 +248,7 @@ void show_stack(struct task_struct *tsk,
* Of course just returning schedule( ) would be pointless so unwind until
* the function is not in schedular code
*/
-unsigned int get_wchan(struct task_struct *tsk)
+unsigned int __get_wchan(struct task_struct *tsk)
{
return arc_unwind_core(tsk, NULL, __get_first_nonsched, NULL);
}
--- a/arch/arm/include/asm/processor.h
+++ b/arch/arm/include/asm/processor.h
@@ -84,7 +84,7 @@ struct task_struct;
/* Free all resources held by a thread. */
extern void release_thread(struct task_struct *);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define task_pt_regs(p) \
((struct pt_regs *)(THREAD_START_SP + task_stack_page(p)) - 1)
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -276,13 +276,11 @@ int copy_thread(unsigned long clone_flag
return 0;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
struct stackframe frame;
unsigned long stack_page;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
frame.fp = thread_saved_fp(p);
frame.sp = thread_saved_sp(p);
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -257,7 +257,7 @@ struct task_struct;
/* Free all resources held by a thread. */
extern void release_thread(struct task_struct *);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
void update_sctlr_el1(u64 sctlr);
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -528,13 +528,11 @@ __notrace_funcgraph struct task_struct *
return last;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
struct stackframe frame;
unsigned long stack_page, ret = 0;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
stack_page = (unsigned long)try_get_task_stack(p);
if (!stack_page)
--- a/arch/csky/include/asm/processor.h
+++ b/arch/csky/include/asm/processor.h
@@ -81,7 +81,7 @@ static inline void release_thread(struct
extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
#define KSTK_ESP(tsk) (task_pt_regs(tsk)->usp)
--- a/arch/csky/kernel/stacktrace.c
+++ b/arch/csky/kernel/stacktrace.c
@@ -111,12 +111,11 @@ static bool save_wchan(unsigned long pc,
return false;
}
-unsigned long get_wchan(struct task_struct *task)
+unsigned long __get_wchan(struct task_struct *task)
{
unsigned long pc = 0;
- if (likely(task && task != current && !task_is_running(task)))
- walk_stackframe(task, NULL, save_wchan, &pc);
+ walk_stackframe(task, NULL, save_wchan, &pc);
return pc;
}
--- a/arch/h8300/include/asm/processor.h
+++ b/arch/h8300/include/asm/processor.h
@@ -105,7 +105,7 @@ static inline void release_thread(struct
{
}
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) \
({ \
--- a/arch/h8300/kernel/process.c
+++ b/arch/h8300/kernel/process.c
@@ -128,15 +128,12 @@ int copy_thread(unsigned long clone_flag
return 0;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long fp, pc;
unsigned long stack_page;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
stack_page = (unsigned long)p;
fp = ((struct pt_regs *)p->thread.ksp)->er6;
do {
--- a/arch/hexagon/include/asm/processor.h
+++ b/arch/hexagon/include/asm/processor.h
@@ -64,7 +64,7 @@ struct thread_struct {
extern void release_thread(struct task_struct *dead_task);
/* Get wait channel for task P. */
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
/* The following stuff is pretty HEXAGON specific. */
--- a/arch/hexagon/kernel/process.c
+++ b/arch/hexagon/kernel/process.c
@@ -130,13 +130,11 @@ void flush_thread(void)
* is an identification of the point at which the scheduler
* was invoked by a blocked thread.
*/
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long fp, pc;
unsigned long stack_page;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
stack_page = (unsigned long)task_stack_page(p);
fp = ((struct hexagon_switch_stack *)p->thread.switch_sp)->fp;
--- a/arch/ia64/include/asm/processor.h
+++ b/arch/ia64/include/asm/processor.h
@@ -330,7 +330,7 @@ struct task_struct;
#define release_thread(dead_task)
/* Get wait channel for task P. */
-extern unsigned long get_wchan (struct task_struct *p);
+extern unsigned long __get_wchan (struct task_struct *p);
/* Return instruction pointer of blocked task TSK. */
#define KSTK_EIP(tsk) \
--- a/arch/ia64/kernel/process.c
+++ b/arch/ia64/kernel/process.c
@@ -523,15 +523,12 @@ exit_thread (struct task_struct *tsk)
}
unsigned long
-get_wchan (struct task_struct *p)
+__get_wchan (struct task_struct *p)
{
struct unw_frame_info info;
unsigned long ip;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
/*
* Note: p may not be a blocked task (it could be current or
* another process running on some other CPU. Rather than
--- a/arch/m68k/include/asm/processor.h
+++ b/arch/m68k/include/asm/processor.h
@@ -125,7 +125,7 @@ static inline void release_thread(struct
{
}
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) \
({ \
--- a/arch/m68k/kernel/process.c
+++ b/arch/m68k/kernel/process.c
@@ -263,13 +263,11 @@ int dump_fpu (struct pt_regs *regs, stru
}
EXPORT_SYMBOL(dump_fpu);
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long fp, pc;
unsigned long stack_page;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
stack_page = (unsigned long)task_stack_page(p);
fp = ((struct switch_stack *)p->thread.ksp)->a6;
--- a/arch/microblaze/include/asm/processor.h
+++ b/arch/microblaze/include/asm/processor.h
@@ -68,7 +68,7 @@ static inline void release_thread(struct
{
}
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
/* The size allocated for kernel stacks. This _must_ be a power of two! */
# define KERNEL_STACK_SIZE 0x2000
--- a/arch/microblaze/kernel/process.c
+++ b/arch/microblaze/kernel/process.c
@@ -112,7 +112,7 @@ int copy_thread(unsigned long clone_flag
return 0;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
/* TBD (used by procfs) */
return 0;
--- a/arch/mips/include/asm/processor.h
+++ b/arch/mips/include/asm/processor.h
@@ -369,7 +369,7 @@ static inline void flush_thread(void)
{
}
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \
THREAD_SIZE - 32 - sizeof(struct pt_regs))
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -511,7 +511,7 @@ static int __init frame_info_init(void)
/*
* Without schedule() frame info, result given by
- * thread_saved_pc() and get_wchan() are not reliable.
+ * thread_saved_pc() and __get_wchan() are not reliable.
*/
if (schedule_mfi.pc_offset < 0)
printk("Can't analyze schedule() prologue at %p\n", schedule);
@@ -652,9 +652,9 @@ unsigned long unwind_stack(struct task_s
#endif
/*
- * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
+ * __get_wchan - a maintenance nightmare^W^Wpain in the ass ...
*/
-unsigned long get_wchan(struct task_struct *task)
+unsigned long __get_wchan(struct task_struct *task)
{
unsigned long pc = 0;
#ifdef CONFIG_KALLSYMS
@@ -662,8 +662,6 @@ unsigned long get_wchan(struct task_stru
unsigned long ra = 0;
#endif
- if (!task || task == current || task_is_running(task))
- goto out;
if (!task_stack_page(task))
goto out;
--- a/arch/nds32/include/asm/processor.h
+++ b/arch/nds32/include/asm/processor.h
@@ -83,7 +83,7 @@ extern struct task_struct *last_task_use
/* Prepare to copy thread state - unlazy all lazy status */
#define prepare_to_copy(tsk) do { } while (0)
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define cpu_relax() barrier()
--- a/arch/nds32/kernel/process.c
+++ b/arch/nds32/kernel/process.c
@@ -233,15 +233,12 @@ int dump_fpu(struct pt_regs *regs, elf_f
EXPORT_SYMBOL(dump_fpu);
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long fp, lr;
unsigned long stack_start, stack_end;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
if (IS_ENABLED(CONFIG_FRAME_POINTER)) {
stack_start = (unsigned long)end_of_stack(p);
stack_end = (unsigned long)task_stack_page(p) + THREAD_SIZE;
@@ -258,5 +255,3 @@ unsigned long get_wchan(struct task_stru
}
return 0;
}
-
-EXPORT_SYMBOL(get_wchan);
--- a/arch/nios2/include/asm/processor.h
+++ b/arch/nios2/include/asm/processor.h
@@ -69,7 +69,7 @@ static inline void release_thread(struct
{
}
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
#define task_pt_regs(p) \
((struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1)
--- a/arch/nios2/kernel/process.c
+++ b/arch/nios2/kernel/process.c
@@ -217,15 +217,12 @@ void dump(struct pt_regs *fp)
pr_emerg("\n\n");
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long fp, pc;
unsigned long stack_page;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
stack_page = (unsigned long)p;
fp = ((struct switch_stack *)p->thread.ksp)->fp; /* ;dgt2 */
do {
--- a/arch/openrisc/include/asm/processor.h
+++ b/arch/openrisc/include/asm/processor.h
@@ -73,7 +73,7 @@ struct thread_struct {
void start_thread(struct pt_regs *regs, unsigned long nip, unsigned long sp);
void release_thread(struct task_struct *);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define cpu_relax() barrier()
--- a/arch/openrisc/kernel/process.c
+++ b/arch/openrisc/kernel/process.c
@@ -263,7 +263,7 @@ void dump_elf_thread(elf_greg_t *dest, s
dest[35] = 0;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
/* TODO */
--- a/arch/parisc/include/asm/processor.h
+++ b/arch/parisc/include/asm/processor.h
@@ -273,7 +273,7 @@ struct mm_struct;
/* Free all resources held by a thread. */
extern void release_thread(struct task_struct *);
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) ((tsk)->thread.regs.iaoq[0])
#define KSTK_ESP(tsk) ((tsk)->thread.regs.gr[30])
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -240,15 +240,12 @@ copy_thread(unsigned long clone_flags, u
}
unsigned long
-get_wchan(struct task_struct *p)
+__get_wchan(struct task_struct *p)
{
struct unwind_frame_info info;
unsigned long ip;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
/*
* These bracket the sleeping functions..
*/
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -300,7 +300,7 @@ struct thread_struct {
#define task_pt_regs(tsk) ((tsk)->thread.regs)
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) ((tsk)->thread.regs? (tsk)->thread.regs->nip: 0)
#define KSTK_ESP(tsk) ((tsk)->thread.regs? (tsk)->thread.regs->gpr[1]: 0)
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -2111,14 +2111,11 @@ int validate_sp(unsigned long sp, struct
EXPORT_SYMBOL(validate_sp);
-static unsigned long __get_wchan(struct task_struct *p)
+static unsigned long ___get_wchan(struct task_struct *p)
{
unsigned long ip, sp;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
sp = p->thread.ksp;
if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD))
return 0;
@@ -2137,14 +2134,14 @@ static unsigned long __get_wchan(struct
return 0;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long ret;
if (!try_get_task_stack(p))
return 0;
- ret = __get_wchan(p);
+ ret = ___get_wchan(p);
put_task_stack(p);
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -66,7 +66,7 @@ static inline void release_thread(struct
{
}
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
static inline void wait_for_interrupt(void)
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -128,16 +128,14 @@ static bool save_wchan(void *arg, unsign
return true;
}
-unsigned long get_wchan(struct task_struct *task)
+unsigned long __get_wchan(struct task_struct *task)
{
unsigned long pc = 0;
- if (likely(task && task != current && !task_is_running(task))) {
- if (!try_get_task_stack(task))
- return 0;
- walk_stackframe(task, NULL, save_wchan, &pc);
- put_task_stack(task);
- }
+ if (!try_get_task_stack(task))
+ return 0;
+ walk_stackframe(task, NULL, save_wchan, &pc);
+ put_task_stack(task);
return pc;
}
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -192,7 +192,7 @@ static inline void release_thread(struct
void guarded_storage_release(struct task_struct *tsk);
void gs_load_bc_cb(struct pt_regs *regs);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define task_pt_regs(tsk) ((struct pt_regs *) \
(task_stack_page(tsk) + THREAD_SIZE) - 1)
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->psw.addr)
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -181,12 +181,12 @@ void execve_tail(void)
asm volatile("sfpc %0" : : "d" (0));
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
struct unwind_state state;
unsigned long ip = 0;
- if (!p || p == current || task_is_running(p) || !task_stack_page(p))
+ if (!task_stack_page(p))
return 0;
if (!try_get_task_stack(p))
--- a/arch/sh/include/asm/processor_32.h
+++ b/arch/sh/include/asm/processor_32.h
@@ -180,7 +180,7 @@ static inline void show_code(struct pt_r
}
#endif
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
#define KSTK_ESP(tsk) (task_pt_regs(tsk)->regs[15])
--- a/arch/sh/kernel/process_32.c
+++ b/arch/sh/kernel/process_32.c
@@ -182,13 +182,10 @@ __switch_to(struct task_struct *prev, st
return prev;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long pc;
- if (!p || p == current || task_is_running(p))
- return 0;
-
/*
* The same comment as on the Alpha applies here, too ...
*/
--- a/arch/sparc/include/asm/processor_32.h
+++ b/arch/sparc/include/asm/processor_32.h
@@ -89,7 +89,7 @@ static inline void start_thread(struct p
/* Free all resources held by a thread. */
#define release_thread(tsk) do { } while(0)
-unsigned long get_wchan(struct task_struct *);
+unsigned long __get_wchan(struct task_struct *);
#define task_pt_regs(tsk) ((tsk)->thread.kregs)
#define KSTK_EIP(tsk) ((tsk)->thread.kregs->pc)
--- a/arch/sparc/include/asm/processor_64.h
+++ b/arch/sparc/include/asm/processor_64.h
@@ -183,7 +183,7 @@ do { \
/* Free all resources held by a thread. */
#define release_thread(tsk) do { } while (0)
-unsigned long get_wchan(struct task_struct *task);
+unsigned long __get_wchan(struct task_struct *task);
#define task_pt_regs(tsk) (task_thread_info(tsk)->kregs)
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->tpc)
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -365,7 +365,7 @@ int copy_thread(unsigned long clone_flag
return 0;
}
-unsigned long get_wchan(struct task_struct *task)
+unsigned long __get_wchan(struct task_struct *task)
{
unsigned long pc, fp, bias = 0;
unsigned long task_base = (unsigned long) task;
@@ -373,9 +373,6 @@ unsigned long get_wchan(struct task_stru
struct reg_window32 *rw;
int count = 0;
- if (!task || task == current || task_is_running(task))
- goto out;
-
fp = task_thread_info(task)->ksp + bias;
do {
/* Bogus frame pointer? */
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -663,7 +663,7 @@ int arch_dup_task_struct(struct task_str
return 0;
}
-unsigned long get_wchan(struct task_struct *task)
+unsigned long __get_wchan(struct task_struct *task)
{
unsigned long pc, fp, bias = 0;
struct thread_info *tp;
@@ -671,9 +671,6 @@ unsigned long get_wchan(struct task_stru
unsigned long ret = 0;
int count = 0;
- if (!task || task == current || task_is_running(task))
- goto out;
-
tp = task_thread_info(task);
bias = STACK_BIAS;
fp = task_thread_info(task)->ksp + bias;
--- a/arch/um/include/asm/processor-generic.h
+++ b/arch/um/include/asm/processor-generic.h
@@ -106,6 +106,6 @@ extern struct cpuinfo_um boot_cpu_data;
#define cache_line_size() (boot_cpu_data.cache_alignment)
#define KSTK_REG(tsk, reg) get_thread_reg(reg, &tsk->thread.switch_buf)
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
#endif
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -364,14 +364,11 @@ unsigned long arch_align_stack(unsigned
}
#endif
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long stack_page, sp, ip;
bool seen_sched = 0;
- if ((p == NULL) || (p == current) || task_is_running(p))
- return 0;
-
stack_page = (unsigned long) task_stack_page(p);
/* Bail if the process has no kernel stack for some reason */
if (stack_page == 0)
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -590,7 +590,7 @@ static inline void load_sp0(unsigned lon
/* Free all resources held by a thread. */
extern void release_thread(struct task_struct *);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
/*
* Generic CPUID function
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -943,13 +943,10 @@ unsigned long arch_randomize_brk(struct
* because the task might wake up and we might look at a stack
* changing under us.
*/
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long entry = 0;
- if (p == current || task_is_running(p))
- return 0;
-
stack_trace_save_tsk(p, &entry, 1, 0);
return entry;
}
--- a/arch/xtensa/include/asm/processor.h
+++ b/arch/xtensa/include/asm/processor.h
@@ -215,7 +215,7 @@ struct mm_struct;
/* Free all resources held by a thread. */
#define release_thread(thread) do { } while(0)
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
#define KSTK_ESP(tsk) (task_pt_regs(tsk)->areg[1])
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -298,15 +298,12 @@ int copy_thread(unsigned long clone_flag
* These bracket the sleeping functions..
*/
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long sp, pc;
unsigned long stack_page = (unsigned long) task_stack_page(p);
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
sp = p->thread.sp;
pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2139,6 +2139,7 @@ static inline void set_task_cpu(struct t
#endif /* CONFIG_SMP */
extern bool sched_task_on_rq(struct task_struct *p);
+extern unsigned long get_wchan(struct task_struct *p);
/*
* In order to reduce various lock holder preemption latencies provide an
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1962,6 +1962,25 @@ bool sched_task_on_rq(struct task_struct
return task_on_rq_queued(p);
}
+unsigned long get_wchan(struct task_struct *p)
+{
+ unsigned long ip = 0;
+ unsigned int state;
+
+ if (!p || p == current)
+ return 0;
+
+ /* Only get wchan if task is blocked and we can keep it that way. */
+ raw_spin_lock_irq(&p->pi_lock);
+ state = READ_ONCE(p->__state);
+ smp_rmb(); /* see try_to_wake_up() */
+ if (state != TASK_RUNNING && state != TASK_WAKING && !p->on_rq)
+ ip = __get_wchan(p);
+ raw_spin_unlock_irq(&p->pi_lock);
+
+ return ip;
+}
+
static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
{
if (!(flags & ENQUEUE_NOCLOCK))
On Fri, Oct 8, 2021 at 1:20 PM Peter Zijlstra <[email protected]> wrote:
> From: Kees Cook <[email protected]>
>
> Having a stable wchan means the process must be blocked and for it to
> stay that way while performing stack unwinding.
>
> Suggested-by: Peter Zijlstra <[email protected]>
> Signed-off-by: Kees Cook <[email protected]>
> Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
> arch/m68k/include/asm/processor.h | 2 +-
> arch/m68k/kernel/process.c | 4 +---
Acked-by: Geert Uytterhoeven <[email protected]>
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
On Fri, Oct 08, 2021 at 01:15:32PM +0200, Peter Zijlstra wrote:
> From: Kees Cook <[email protected]>
>
> Having a stable wchan means the process must be blocked and for it to
> stay that way while performing stack unwinding.
>
> Suggested-by: Peter Zijlstra <[email protected]>
> Signed-off-by: Kees Cook <[email protected]>
> Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
FWIW, this seems to wpork on arm64:
Tested-by: Mark Rutland <[email protected]> [arm64]
Mark.
> ---
> arch/alpha/include/asm/processor.h | 2 +-
> arch/alpha/kernel/process.c | 5 ++---
> arch/arc/include/asm/processor.h | 2 +-
> arch/arc/kernel/stacktrace.c | 4 ++--
> arch/arm/include/asm/processor.h | 2 +-
> arch/arm/kernel/process.c | 4 +---
> arch/arm64/include/asm/processor.h | 2 +-
> arch/arm64/kernel/process.c | 4 +---
> arch/csky/include/asm/processor.h | 2 +-
> arch/csky/kernel/stacktrace.c | 5 ++---
> arch/h8300/include/asm/processor.h | 2 +-
> arch/h8300/kernel/process.c | 5 +----
> arch/hexagon/include/asm/processor.h | 2 +-
> arch/hexagon/kernel/process.c | 4 +---
> arch/ia64/include/asm/processor.h | 2 +-
> arch/ia64/kernel/process.c | 5 +----
> arch/m68k/include/asm/processor.h | 2 +-
> arch/m68k/kernel/process.c | 4 +---
> arch/microblaze/include/asm/processor.h | 2 +-
> arch/microblaze/kernel/process.c | 2 +-
> arch/mips/include/asm/processor.h | 2 +-
> arch/mips/kernel/process.c | 8 +++-----
> arch/nds32/include/asm/processor.h | 2 +-
> arch/nds32/kernel/process.c | 7 +------
> arch/nios2/include/asm/processor.h | 2 +-
> arch/nios2/kernel/process.c | 5 +----
> arch/openrisc/include/asm/processor.h | 2 +-
> arch/openrisc/kernel/process.c | 2 +-
> arch/parisc/include/asm/processor.h | 2 +-
> arch/parisc/kernel/process.c | 5 +----
> arch/powerpc/include/asm/processor.h | 2 +-
> arch/powerpc/kernel/process.c | 9 +++------
> arch/riscv/include/asm/processor.h | 2 +-
> arch/riscv/kernel/stacktrace.c | 12 +++++-------
> arch/s390/include/asm/processor.h | 2 +-
> arch/s390/kernel/process.c | 4 ++--
> arch/sh/include/asm/processor_32.h | 2 +-
> arch/sh/kernel/process_32.c | 5 +----
> arch/sparc/include/asm/processor_32.h | 2 +-
> arch/sparc/include/asm/processor_64.h | 2 +-
> arch/sparc/kernel/process_32.c | 5 +----
> arch/sparc/kernel/process_64.c | 5 +----
> arch/um/include/asm/processor-generic.h | 2 +-
> arch/um/kernel/process.c | 5 +----
> arch/x86/include/asm/processor.h | 2 +-
> arch/x86/kernel/process.c | 5 +----
> arch/xtensa/include/asm/processor.h | 2 +-
> arch/xtensa/kernel/process.c | 5 +----
> include/linux/sched.h | 1 +
> kernel/sched/core.c | 19 +++++++++++++++++++
> 50 files changed, 80 insertions(+), 112 deletions(-)
>
> --- a/arch/alpha/include/asm/processor.h
> +++ b/arch/alpha/include/asm/processor.h
> @@ -42,7 +42,7 @@ extern void start_thread(struct pt_regs
> struct task_struct;
> extern void release_thread(struct task_struct *);
>
> -unsigned long get_wchan(struct task_struct *p);
> +unsigned long __get_wchan(struct task_struct *p);
>
> #define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
>
> --- a/arch/alpha/kernel/process.c
> +++ b/arch/alpha/kernel/process.c
> @@ -376,12 +376,11 @@ thread_saved_pc(struct task_struct *t)
> }
>
> unsigned long
> -get_wchan(struct task_struct *p)
> +__get_wchan(struct task_struct *p)
> {
> unsigned long schedule_frame;
> unsigned long pc;
> - if (!p || p == current || task_is_running(p))
> - return 0;
> +
> /*
> * This one depends on the frame size of schedule(). Do a
> * "disass schedule" in gdb to find the frame size. Also, the
> --- a/arch/arc/include/asm/processor.h
> +++ b/arch/arc/include/asm/processor.h
> @@ -70,7 +70,7 @@ struct task_struct;
> extern void start_thread(struct pt_regs * regs, unsigned long pc,
> unsigned long usp);
>
> -extern unsigned int get_wchan(struct task_struct *p);
> +extern unsigned int __get_wchan(struct task_struct *p);
>
> #endif /* !__ASSEMBLY__ */
>
> --- a/arch/arc/kernel/stacktrace.c
> +++ b/arch/arc/kernel/stacktrace.c
> @@ -15,7 +15,7 @@
> * = specifics of data structs where trace is saved(CONFIG_STACKTRACE etc)
> *
> * vineetg: March 2009
> - * -Implemented correct versions of thread_saved_pc() and get_wchan()
> + * -Implemented correct versions of thread_saved_pc() and __get_wchan()
> *
> * rajeshwarr: 2008
> * -Initial implementation
> @@ -248,7 +248,7 @@ void show_stack(struct task_struct *tsk,
> * Of course just returning schedule( ) would be pointless so unwind until
> * the function is not in schedular code
> */
> -unsigned int get_wchan(struct task_struct *tsk)
> +unsigned int __get_wchan(struct task_struct *tsk)
> {
> return arc_unwind_core(tsk, NULL, __get_first_nonsched, NULL);
> }
> --- a/arch/arm/include/asm/processor.h
> +++ b/arch/arm/include/asm/processor.h
> @@ -84,7 +84,7 @@ struct task_struct;
> /* Free all resources held by a thread. */
> extern void release_thread(struct task_struct *);
>
> -unsigned long get_wchan(struct task_struct *p);
> +unsigned long __get_wchan(struct task_struct *p);
>
> #define task_pt_regs(p) \
> ((struct pt_regs *)(THREAD_START_SP + task_stack_page(p)) - 1)
> --- a/arch/arm/kernel/process.c
> +++ b/arch/arm/kernel/process.c
> @@ -276,13 +276,11 @@ int copy_thread(unsigned long clone_flag
> return 0;
> }
>
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> struct stackframe frame;
> unsigned long stack_page;
> int count = 0;
> - if (!p || p == current || task_is_running(p))
> - return 0;
>
> frame.fp = thread_saved_fp(p);
> frame.sp = thread_saved_sp(p);
> --- a/arch/arm64/include/asm/processor.h
> +++ b/arch/arm64/include/asm/processor.h
> @@ -257,7 +257,7 @@ struct task_struct;
> /* Free all resources held by a thread. */
> extern void release_thread(struct task_struct *);
>
> -unsigned long get_wchan(struct task_struct *p);
> +unsigned long __get_wchan(struct task_struct *p);
>
> void update_sctlr_el1(u64 sctlr);
>
> --- a/arch/arm64/kernel/process.c
> +++ b/arch/arm64/kernel/process.c
> @@ -528,13 +528,11 @@ __notrace_funcgraph struct task_struct *
> return last;
> }
>
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> struct stackframe frame;
> unsigned long stack_page, ret = 0;
> int count = 0;
> - if (!p || p == current || task_is_running(p))
> - return 0;
>
> stack_page = (unsigned long)try_get_task_stack(p);
> if (!stack_page)
> --- a/arch/csky/include/asm/processor.h
> +++ b/arch/csky/include/asm/processor.h
> @@ -81,7 +81,7 @@ static inline void release_thread(struct
>
> extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
>
> -unsigned long get_wchan(struct task_struct *p);
> +unsigned long __get_wchan(struct task_struct *p);
>
> #define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
> #define KSTK_ESP(tsk) (task_pt_regs(tsk)->usp)
> --- a/arch/csky/kernel/stacktrace.c
> +++ b/arch/csky/kernel/stacktrace.c
> @@ -111,12 +111,11 @@ static bool save_wchan(unsigned long pc,
> return false;
> }
>
> -unsigned long get_wchan(struct task_struct *task)
> +unsigned long __get_wchan(struct task_struct *task)
> {
> unsigned long pc = 0;
>
> - if (likely(task && task != current && !task_is_running(task)))
> - walk_stackframe(task, NULL, save_wchan, &pc);
> + walk_stackframe(task, NULL, save_wchan, &pc);
> return pc;
> }
>
> --- a/arch/h8300/include/asm/processor.h
> +++ b/arch/h8300/include/asm/processor.h
> @@ -105,7 +105,7 @@ static inline void release_thread(struct
> {
> }
>
> -unsigned long get_wchan(struct task_struct *p);
> +unsigned long __get_wchan(struct task_struct *p);
>
> #define KSTK_EIP(tsk) \
> ({ \
> --- a/arch/h8300/kernel/process.c
> +++ b/arch/h8300/kernel/process.c
> @@ -128,15 +128,12 @@ int copy_thread(unsigned long clone_flag
> return 0;
> }
>
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> unsigned long fp, pc;
> unsigned long stack_page;
> int count = 0;
>
> - if (!p || p == current || task_is_running(p))
> - return 0;
> -
> stack_page = (unsigned long)p;
> fp = ((struct pt_regs *)p->thread.ksp)->er6;
> do {
> --- a/arch/hexagon/include/asm/processor.h
> +++ b/arch/hexagon/include/asm/processor.h
> @@ -64,7 +64,7 @@ struct thread_struct {
> extern void release_thread(struct task_struct *dead_task);
>
> /* Get wait channel for task P. */
> -extern unsigned long get_wchan(struct task_struct *p);
> +extern unsigned long __get_wchan(struct task_struct *p);
>
> /* The following stuff is pretty HEXAGON specific. */
>
> --- a/arch/hexagon/kernel/process.c
> +++ b/arch/hexagon/kernel/process.c
> @@ -130,13 +130,11 @@ void flush_thread(void)
> * is an identification of the point at which the scheduler
> * was invoked by a blocked thread.
> */
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> unsigned long fp, pc;
> unsigned long stack_page;
> int count = 0;
> - if (!p || p == current || task_is_running(p))
> - return 0;
>
> stack_page = (unsigned long)task_stack_page(p);
> fp = ((struct hexagon_switch_stack *)p->thread.switch_sp)->fp;
> --- a/arch/ia64/include/asm/processor.h
> +++ b/arch/ia64/include/asm/processor.h
> @@ -330,7 +330,7 @@ struct task_struct;
> #define release_thread(dead_task)
>
> /* Get wait channel for task P. */
> -extern unsigned long get_wchan (struct task_struct *p);
> +extern unsigned long __get_wchan (struct task_struct *p);
>
> /* Return instruction pointer of blocked task TSK. */
> #define KSTK_EIP(tsk) \
> --- a/arch/ia64/kernel/process.c
> +++ b/arch/ia64/kernel/process.c
> @@ -523,15 +523,12 @@ exit_thread (struct task_struct *tsk)
> }
>
> unsigned long
> -get_wchan (struct task_struct *p)
> +__get_wchan (struct task_struct *p)
> {
> struct unw_frame_info info;
> unsigned long ip;
> int count = 0;
>
> - if (!p || p == current || task_is_running(p))
> - return 0;
> -
> /*
> * Note: p may not be a blocked task (it could be current or
> * another process running on some other CPU. Rather than
> --- a/arch/m68k/include/asm/processor.h
> +++ b/arch/m68k/include/asm/processor.h
> @@ -125,7 +125,7 @@ static inline void release_thread(struct
> {
> }
>
> -unsigned long get_wchan(struct task_struct *p);
> +unsigned long __get_wchan(struct task_struct *p);
>
> #define KSTK_EIP(tsk) \
> ({ \
> --- a/arch/m68k/kernel/process.c
> +++ b/arch/m68k/kernel/process.c
> @@ -263,13 +263,11 @@ int dump_fpu (struct pt_regs *regs, stru
> }
> EXPORT_SYMBOL(dump_fpu);
>
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> unsigned long fp, pc;
> unsigned long stack_page;
> int count = 0;
> - if (!p || p == current || task_is_running(p))
> - return 0;
>
> stack_page = (unsigned long)task_stack_page(p);
> fp = ((struct switch_stack *)p->thread.ksp)->a6;
> --- a/arch/microblaze/include/asm/processor.h
> +++ b/arch/microblaze/include/asm/processor.h
> @@ -68,7 +68,7 @@ static inline void release_thread(struct
> {
> }
>
> -unsigned long get_wchan(struct task_struct *p);
> +unsigned long __get_wchan(struct task_struct *p);
>
> /* The size allocated for kernel stacks. This _must_ be a power of two! */
> # define KERNEL_STACK_SIZE 0x2000
> --- a/arch/microblaze/kernel/process.c
> +++ b/arch/microblaze/kernel/process.c
> @@ -112,7 +112,7 @@ int copy_thread(unsigned long clone_flag
> return 0;
> }
>
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> /* TBD (used by procfs) */
> return 0;
> --- a/arch/mips/include/asm/processor.h
> +++ b/arch/mips/include/asm/processor.h
> @@ -369,7 +369,7 @@ static inline void flush_thread(void)
> {
> }
>
> -unsigned long get_wchan(struct task_struct *p);
> +unsigned long __get_wchan(struct task_struct *p);
>
> #define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \
> THREAD_SIZE - 32 - sizeof(struct pt_regs))
> --- a/arch/mips/kernel/process.c
> +++ b/arch/mips/kernel/process.c
> @@ -511,7 +511,7 @@ static int __init frame_info_init(void)
>
> /*
> * Without schedule() frame info, result given by
> - * thread_saved_pc() and get_wchan() are not reliable.
> + * thread_saved_pc() and __get_wchan() are not reliable.
> */
> if (schedule_mfi.pc_offset < 0)
> printk("Can't analyze schedule() prologue at %p\n", schedule);
> @@ -652,9 +652,9 @@ unsigned long unwind_stack(struct task_s
> #endif
>
> /*
> - * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
> + * __get_wchan - a maintenance nightmare^W^Wpain in the ass ...
> */
> -unsigned long get_wchan(struct task_struct *task)
> +unsigned long __get_wchan(struct task_struct *task)
> {
> unsigned long pc = 0;
> #ifdef CONFIG_KALLSYMS
> @@ -662,8 +662,6 @@ unsigned long get_wchan(struct task_stru
> unsigned long ra = 0;
> #endif
>
> - if (!task || task == current || task_is_running(task))
> - goto out;
> if (!task_stack_page(task))
> goto out;
>
> --- a/arch/nds32/include/asm/processor.h
> +++ b/arch/nds32/include/asm/processor.h
> @@ -83,7 +83,7 @@ extern struct task_struct *last_task_use
> /* Prepare to copy thread state - unlazy all lazy status */
> #define prepare_to_copy(tsk) do { } while (0)
>
> -unsigned long get_wchan(struct task_struct *p);
> +unsigned long __get_wchan(struct task_struct *p);
>
> #define cpu_relax() barrier()
>
> --- a/arch/nds32/kernel/process.c
> +++ b/arch/nds32/kernel/process.c
> @@ -233,15 +233,12 @@ int dump_fpu(struct pt_regs *regs, elf_f
>
> EXPORT_SYMBOL(dump_fpu);
>
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> unsigned long fp, lr;
> unsigned long stack_start, stack_end;
> int count = 0;
>
> - if (!p || p == current || task_is_running(p))
> - return 0;
> -
> if (IS_ENABLED(CONFIG_FRAME_POINTER)) {
> stack_start = (unsigned long)end_of_stack(p);
> stack_end = (unsigned long)task_stack_page(p) + THREAD_SIZE;
> @@ -258,5 +255,3 @@ unsigned long get_wchan(struct task_stru
> }
> return 0;
> }
> -
> -EXPORT_SYMBOL(get_wchan);
> --- a/arch/nios2/include/asm/processor.h
> +++ b/arch/nios2/include/asm/processor.h
> @@ -69,7 +69,7 @@ static inline void release_thread(struct
> {
> }
>
> -extern unsigned long get_wchan(struct task_struct *p);
> +extern unsigned long __get_wchan(struct task_struct *p);
>
> #define task_pt_regs(p) \
> ((struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1)
> --- a/arch/nios2/kernel/process.c
> +++ b/arch/nios2/kernel/process.c
> @@ -217,15 +217,12 @@ void dump(struct pt_regs *fp)
> pr_emerg("\n\n");
> }
>
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> unsigned long fp, pc;
> unsigned long stack_page;
> int count = 0;
>
> - if (!p || p == current || task_is_running(p))
> - return 0;
> -
> stack_page = (unsigned long)p;
> fp = ((struct switch_stack *)p->thread.ksp)->fp; /* ;dgt2 */
> do {
> --- a/arch/openrisc/include/asm/processor.h
> +++ b/arch/openrisc/include/asm/processor.h
> @@ -73,7 +73,7 @@ struct thread_struct {
>
> void start_thread(struct pt_regs *regs, unsigned long nip, unsigned long sp);
> void release_thread(struct task_struct *);
> -unsigned long get_wchan(struct task_struct *p);
> +unsigned long __get_wchan(struct task_struct *p);
>
> #define cpu_relax() barrier()
>
> --- a/arch/openrisc/kernel/process.c
> +++ b/arch/openrisc/kernel/process.c
> @@ -263,7 +263,7 @@ void dump_elf_thread(elf_greg_t *dest, s
> dest[35] = 0;
> }
>
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> /* TODO */
>
> --- a/arch/parisc/include/asm/processor.h
> +++ b/arch/parisc/include/asm/processor.h
> @@ -273,7 +273,7 @@ struct mm_struct;
> /* Free all resources held by a thread. */
> extern void release_thread(struct task_struct *);
>
> -extern unsigned long get_wchan(struct task_struct *p);
> +extern unsigned long __get_wchan(struct task_struct *p);
>
> #define KSTK_EIP(tsk) ((tsk)->thread.regs.iaoq[0])
> #define KSTK_ESP(tsk) ((tsk)->thread.regs.gr[30])
> --- a/arch/parisc/kernel/process.c
> +++ b/arch/parisc/kernel/process.c
> @@ -240,15 +240,12 @@ copy_thread(unsigned long clone_flags, u
> }
>
> unsigned long
> -get_wchan(struct task_struct *p)
> +__get_wchan(struct task_struct *p)
> {
> struct unwind_frame_info info;
> unsigned long ip;
> int count = 0;
>
> - if (!p || p == current || task_is_running(p))
> - return 0;
> -
> /*
> * These bracket the sleeping functions..
> */
> --- a/arch/powerpc/include/asm/processor.h
> +++ b/arch/powerpc/include/asm/processor.h
> @@ -300,7 +300,7 @@ struct thread_struct {
>
> #define task_pt_regs(tsk) ((tsk)->thread.regs)
>
> -unsigned long get_wchan(struct task_struct *p);
> +unsigned long __get_wchan(struct task_struct *p);
>
> #define KSTK_EIP(tsk) ((tsk)->thread.regs? (tsk)->thread.regs->nip: 0)
> #define KSTK_ESP(tsk) ((tsk)->thread.regs? (tsk)->thread.regs->gpr[1]: 0)
> --- a/arch/powerpc/kernel/process.c
> +++ b/arch/powerpc/kernel/process.c
> @@ -2111,14 +2111,11 @@ int validate_sp(unsigned long sp, struct
>
> EXPORT_SYMBOL(validate_sp);
>
> -static unsigned long __get_wchan(struct task_struct *p)
> +static unsigned long ___get_wchan(struct task_struct *p)
> {
> unsigned long ip, sp;
> int count = 0;
>
> - if (!p || p == current || task_is_running(p))
> - return 0;
> -
> sp = p->thread.ksp;
> if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD))
> return 0;
> @@ -2137,14 +2134,14 @@ static unsigned long __get_wchan(struct
> return 0;
> }
>
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> unsigned long ret;
>
> if (!try_get_task_stack(p))
> return 0;
>
> - ret = __get_wchan(p);
> + ret = ___get_wchan(p);
>
> put_task_stack(p);
>
> --- a/arch/riscv/include/asm/processor.h
> +++ b/arch/riscv/include/asm/processor.h
> @@ -66,7 +66,7 @@ static inline void release_thread(struct
> {
> }
>
> -extern unsigned long get_wchan(struct task_struct *p);
> +extern unsigned long __get_wchan(struct task_struct *p);
>
>
> static inline void wait_for_interrupt(void)
> --- a/arch/riscv/kernel/stacktrace.c
> +++ b/arch/riscv/kernel/stacktrace.c
> @@ -128,16 +128,14 @@ static bool save_wchan(void *arg, unsign
> return true;
> }
>
> -unsigned long get_wchan(struct task_struct *task)
> +unsigned long __get_wchan(struct task_struct *task)
> {
> unsigned long pc = 0;
>
> - if (likely(task && task != current && !task_is_running(task))) {
> - if (!try_get_task_stack(task))
> - return 0;
> - walk_stackframe(task, NULL, save_wchan, &pc);
> - put_task_stack(task);
> - }
> + if (!try_get_task_stack(task))
> + return 0;
> + walk_stackframe(task, NULL, save_wchan, &pc);
> + put_task_stack(task);
> return pc;
> }
>
> --- a/arch/s390/include/asm/processor.h
> +++ b/arch/s390/include/asm/processor.h
> @@ -192,7 +192,7 @@ static inline void release_thread(struct
> void guarded_storage_release(struct task_struct *tsk);
> void gs_load_bc_cb(struct pt_regs *regs);
>
> -unsigned long get_wchan(struct task_struct *p);
> +unsigned long __get_wchan(struct task_struct *p);
> #define task_pt_regs(tsk) ((struct pt_regs *) \
> (task_stack_page(tsk) + THREAD_SIZE) - 1)
> #define KSTK_EIP(tsk) (task_pt_regs(tsk)->psw.addr)
> --- a/arch/s390/kernel/process.c
> +++ b/arch/s390/kernel/process.c
> @@ -181,12 +181,12 @@ void execve_tail(void)
> asm volatile("sfpc %0" : : "d" (0));
> }
>
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> struct unwind_state state;
> unsigned long ip = 0;
>
> - if (!p || p == current || task_is_running(p) || !task_stack_page(p))
> + if (!task_stack_page(p))
> return 0;
>
> if (!try_get_task_stack(p))
> --- a/arch/sh/include/asm/processor_32.h
> +++ b/arch/sh/include/asm/processor_32.h
> @@ -180,7 +180,7 @@ static inline void show_code(struct pt_r
> }
> #endif
>
> -extern unsigned long get_wchan(struct task_struct *p);
> +extern unsigned long __get_wchan(struct task_struct *p);
>
> #define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
> #define KSTK_ESP(tsk) (task_pt_regs(tsk)->regs[15])
> --- a/arch/sh/kernel/process_32.c
> +++ b/arch/sh/kernel/process_32.c
> @@ -182,13 +182,10 @@ __switch_to(struct task_struct *prev, st
> return prev;
> }
>
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> unsigned long pc;
>
> - if (!p || p == current || task_is_running(p))
> - return 0;
> -
> /*
> * The same comment as on the Alpha applies here, too ...
> */
> --- a/arch/sparc/include/asm/processor_32.h
> +++ b/arch/sparc/include/asm/processor_32.h
> @@ -89,7 +89,7 @@ static inline void start_thread(struct p
> /* Free all resources held by a thread. */
> #define release_thread(tsk) do { } while(0)
>
> -unsigned long get_wchan(struct task_struct *);
> +unsigned long __get_wchan(struct task_struct *);
>
> #define task_pt_regs(tsk) ((tsk)->thread.kregs)
> #define KSTK_EIP(tsk) ((tsk)->thread.kregs->pc)
> --- a/arch/sparc/include/asm/processor_64.h
> +++ b/arch/sparc/include/asm/processor_64.h
> @@ -183,7 +183,7 @@ do { \
> /* Free all resources held by a thread. */
> #define release_thread(tsk) do { } while (0)
>
> -unsigned long get_wchan(struct task_struct *task);
> +unsigned long __get_wchan(struct task_struct *task);
>
> #define task_pt_regs(tsk) (task_thread_info(tsk)->kregs)
> #define KSTK_EIP(tsk) (task_pt_regs(tsk)->tpc)
> --- a/arch/sparc/kernel/process_32.c
> +++ b/arch/sparc/kernel/process_32.c
> @@ -365,7 +365,7 @@ int copy_thread(unsigned long clone_flag
> return 0;
> }
>
> -unsigned long get_wchan(struct task_struct *task)
> +unsigned long __get_wchan(struct task_struct *task)
> {
> unsigned long pc, fp, bias = 0;
> unsigned long task_base = (unsigned long) task;
> @@ -373,9 +373,6 @@ unsigned long get_wchan(struct task_stru
> struct reg_window32 *rw;
> int count = 0;
>
> - if (!task || task == current || task_is_running(task))
> - goto out;
> -
> fp = task_thread_info(task)->ksp + bias;
> do {
> /* Bogus frame pointer? */
> --- a/arch/sparc/kernel/process_64.c
> +++ b/arch/sparc/kernel/process_64.c
> @@ -663,7 +663,7 @@ int arch_dup_task_struct(struct task_str
> return 0;
> }
>
> -unsigned long get_wchan(struct task_struct *task)
> +unsigned long __get_wchan(struct task_struct *task)
> {
> unsigned long pc, fp, bias = 0;
> struct thread_info *tp;
> @@ -671,9 +671,6 @@ unsigned long get_wchan(struct task_stru
> unsigned long ret = 0;
> int count = 0;
>
> - if (!task || task == current || task_is_running(task))
> - goto out;
> -
> tp = task_thread_info(task);
> bias = STACK_BIAS;
> fp = task_thread_info(task)->ksp + bias;
> --- a/arch/um/include/asm/processor-generic.h
> +++ b/arch/um/include/asm/processor-generic.h
> @@ -106,6 +106,6 @@ extern struct cpuinfo_um boot_cpu_data;
> #define cache_line_size() (boot_cpu_data.cache_alignment)
>
> #define KSTK_REG(tsk, reg) get_thread_reg(reg, &tsk->thread.switch_buf)
> -extern unsigned long get_wchan(struct task_struct *p);
> +extern unsigned long __get_wchan(struct task_struct *p);
>
> #endif
> --- a/arch/um/kernel/process.c
> +++ b/arch/um/kernel/process.c
> @@ -364,14 +364,11 @@ unsigned long arch_align_stack(unsigned
> }
> #endif
>
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> unsigned long stack_page, sp, ip;
> bool seen_sched = 0;
>
> - if ((p == NULL) || (p == current) || task_is_running(p))
> - return 0;
> -
> stack_page = (unsigned long) task_stack_page(p);
> /* Bail if the process has no kernel stack for some reason */
> if (stack_page == 0)
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -590,7 +590,7 @@ static inline void load_sp0(unsigned lon
> /* Free all resources held by a thread. */
> extern void release_thread(struct task_struct *);
>
> -unsigned long get_wchan(struct task_struct *p);
> +unsigned long __get_wchan(struct task_struct *p);
>
> /*
> * Generic CPUID function
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -943,13 +943,10 @@ unsigned long arch_randomize_brk(struct
> * because the task might wake up and we might look at a stack
> * changing under us.
> */
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> unsigned long entry = 0;
>
> - if (p == current || task_is_running(p))
> - return 0;
> -
> stack_trace_save_tsk(p, &entry, 1, 0);
> return entry;
> }
> --- a/arch/xtensa/include/asm/processor.h
> +++ b/arch/xtensa/include/asm/processor.h
> @@ -215,7 +215,7 @@ struct mm_struct;
> /* Free all resources held by a thread. */
> #define release_thread(thread) do { } while(0)
>
> -extern unsigned long get_wchan(struct task_struct *p);
> +extern unsigned long __get_wchan(struct task_struct *p);
>
> #define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
> #define KSTK_ESP(tsk) (task_pt_regs(tsk)->areg[1])
> --- a/arch/xtensa/kernel/process.c
> +++ b/arch/xtensa/kernel/process.c
> @@ -298,15 +298,12 @@ int copy_thread(unsigned long clone_flag
> * These bracket the sleeping functions..
> */
>
> -unsigned long get_wchan(struct task_struct *p)
> +unsigned long __get_wchan(struct task_struct *p)
> {
> unsigned long sp, pc;
> unsigned long stack_page = (unsigned long) task_stack_page(p);
> int count = 0;
>
> - if (!p || p == current || task_is_running(p))
> - return 0;
> -
> sp = p->thread.sp;
> pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
>
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -2139,6 +2139,7 @@ static inline void set_task_cpu(struct t
> #endif /* CONFIG_SMP */
>
> extern bool sched_task_on_rq(struct task_struct *p);
> +extern unsigned long get_wchan(struct task_struct *p);
>
> /*
> * In order to reduce various lock holder preemption latencies provide an
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1962,6 +1962,25 @@ bool sched_task_on_rq(struct task_struct
> return task_on_rq_queued(p);
> }
>
> +unsigned long get_wchan(struct task_struct *p)
> +{
> + unsigned long ip = 0;
> + unsigned int state;
> +
> + if (!p || p == current)
> + return 0;
> +
> + /* Only get wchan if task is blocked and we can keep it that way. */
> + raw_spin_lock_irq(&p->pi_lock);
> + state = READ_ONCE(p->__state);
> + smp_rmb(); /* see try_to_wake_up() */
> + if (state != TASK_RUNNING && state != TASK_WAKING && !p->on_rq)
> + ip = __get_wchan(p);
> + raw_spin_unlock_irq(&p->pi_lock);
> +
> + return ip;
> +}
> +
> static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
> {
> if (!(flags & ENQUEUE_NOCLOCK))
>
>
On Fri, Oct 08, 2021 at 01:15:32PM +0200, Peter Zijlstra wrote:
> From: Kees Cook <[email protected]>
>
> Having a stable wchan means the process must be blocked and for it to
> stay that way while performing stack unwinding.
>
> Suggested-by: Peter Zijlstra <[email protected]>
> Signed-off-by: Kees Cook <[email protected]>
> Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Russell King (Oracle) <[email protected]> [arm]
I will eventually get around to test this once I've caught up.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
The following commit has been merged into the sched/core branch of tip:
Commit-ID: 42a20f86dc19f9282d974df0ba4d226c865ab9dd
Gitweb: https://git.kernel.org/tip/42a20f86dc19f9282d974df0ba4d226c865ab9dd
Author: Kees Cook <[email protected]>
AuthorDate: Wed, 29 Sep 2021 15:02:14 -07:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Fri, 15 Oct 2021 11:25:14 +02:00
sched: Add wrapper for get_wchan() to keep task blocked
Having a stable wchan means the process must be blocked and for it to
stay that way while performing stack unwinding.
Suggested-by: Peter Zijlstra <[email protected]>
Signed-off-by: Kees Cook <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Acked-by: Geert Uytterhoeven <[email protected]>
Acked-by: Russell King (Oracle) <[email protected]> [arm]
Tested-by: Mark Rutland <[email protected]> [arm64]
Link: https://lkml.kernel.org/r/[email protected]
---
arch/alpha/include/asm/processor.h | 2 +-
arch/alpha/kernel/process.c | 5 ++---
arch/arc/include/asm/processor.h | 2 +-
arch/arc/kernel/stacktrace.c | 4 ++--
arch/arm/include/asm/processor.h | 2 +-
arch/arm/kernel/process.c | 4 +---
arch/arm64/include/asm/processor.h | 2 +-
arch/arm64/kernel/process.c | 4 +---
arch/csky/include/asm/processor.h | 2 +-
arch/csky/kernel/stacktrace.c | 5 ++---
arch/h8300/include/asm/processor.h | 2 +-
arch/h8300/kernel/process.c | 5 +----
arch/hexagon/include/asm/processor.h | 2 +-
arch/hexagon/kernel/process.c | 4 +---
arch/ia64/include/asm/processor.h | 2 +-
arch/ia64/kernel/process.c | 5 +----
arch/m68k/include/asm/processor.h | 2 +-
arch/m68k/kernel/process.c | 4 +---
arch/microblaze/include/asm/processor.h | 2 +-
arch/microblaze/kernel/process.c | 2 +-
arch/mips/include/asm/processor.h | 2 +-
arch/mips/kernel/process.c | 8 +++-----
arch/nds32/include/asm/processor.h | 2 +-
arch/nds32/kernel/process.c | 7 +------
arch/nios2/include/asm/processor.h | 2 +-
arch/nios2/kernel/process.c | 5 +----
arch/openrisc/include/asm/processor.h | 2 +-
arch/openrisc/kernel/process.c | 2 +-
arch/parisc/include/asm/processor.h | 2 +-
arch/parisc/kernel/process.c | 5 +----
arch/powerpc/include/asm/processor.h | 2 +-
arch/powerpc/kernel/process.c | 9 +++------
arch/riscv/include/asm/processor.h | 2 +-
arch/riscv/kernel/stacktrace.c | 12 +++++-------
arch/s390/include/asm/processor.h | 2 +-
arch/s390/kernel/process.c | 4 ++--
arch/sh/include/asm/processor_32.h | 2 +-
arch/sh/kernel/process_32.c | 5 +----
arch/sparc/include/asm/processor_32.h | 2 +-
arch/sparc/include/asm/processor_64.h | 2 +-
arch/sparc/kernel/process_32.c | 5 +----
arch/sparc/kernel/process_64.c | 5 +----
arch/um/include/asm/processor-generic.h | 2 +-
arch/um/kernel/process.c | 5 +----
arch/x86/include/asm/processor.h | 2 +-
arch/x86/kernel/process.c | 5 +----
arch/xtensa/include/asm/processor.h | 2 +-
arch/xtensa/kernel/process.c | 5 +----
include/linux/sched.h | 1 +
kernel/sched/core.c | 19 +++++++++++++++++++
50 files changed, 80 insertions(+), 112 deletions(-)
diff --git a/arch/alpha/include/asm/processor.h b/arch/alpha/include/asm/processor.h
index 6100431..090499c 100644
--- a/arch/alpha/include/asm/processor.h
+++ b/arch/alpha/include/asm/processor.h
@@ -42,7 +42,7 @@ extern void start_thread(struct pt_regs *, unsigned long, unsigned long);
struct task_struct;
extern void release_thread(struct task_struct *);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c
index a5123ea..5f85270 100644
--- a/arch/alpha/kernel/process.c
+++ b/arch/alpha/kernel/process.c
@@ -376,12 +376,11 @@ thread_saved_pc(struct task_struct *t)
}
unsigned long
-get_wchan(struct task_struct *p)
+__get_wchan(struct task_struct *p)
{
unsigned long schedule_frame;
unsigned long pc;
- if (!p || p == current || task_is_running(p))
- return 0;
+
/*
* This one depends on the frame size of schedule(). Do a
* "disass schedule" in gdb to find the frame size. Also, the
diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h
index f28afcf..54db9d7 100644
--- a/arch/arc/include/asm/processor.h
+++ b/arch/arc/include/asm/processor.h
@@ -70,7 +70,7 @@ struct task_struct;
extern void start_thread(struct pt_regs * regs, unsigned long pc,
unsigned long usp);
-extern unsigned int get_wchan(struct task_struct *p);
+extern unsigned int __get_wchan(struct task_struct *p);
#endif /* !__ASSEMBLY__ */
diff --git a/arch/arc/kernel/stacktrace.c b/arch/arc/kernel/stacktrace.c
index c376ff3..5372dc0 100644
--- a/arch/arc/kernel/stacktrace.c
+++ b/arch/arc/kernel/stacktrace.c
@@ -15,7 +15,7 @@
* = specifics of data structs where trace is saved(CONFIG_STACKTRACE etc)
*
* vineetg: March 2009
- * -Implemented correct versions of thread_saved_pc() and get_wchan()
+ * -Implemented correct versions of thread_saved_pc() and __get_wchan()
*
* rajeshwarr: 2008
* -Initial implementation
@@ -248,7 +248,7 @@ void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl)
* Of course just returning schedule( ) would be pointless so unwind until
* the function is not in schedular code
*/
-unsigned int get_wchan(struct task_struct *tsk)
+unsigned int __get_wchan(struct task_struct *tsk)
{
return arc_unwind_core(tsk, NULL, __get_first_nonsched, NULL);
}
diff --git a/arch/arm/include/asm/processor.h b/arch/arm/include/asm/processor.h
index 9e6b972..6af68ed 100644
--- a/arch/arm/include/asm/processor.h
+++ b/arch/arm/include/asm/processor.h
@@ -84,7 +84,7 @@ struct task_struct;
/* Free all resources held by a thread. */
extern void release_thread(struct task_struct *);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define task_pt_regs(p) \
((struct pt_regs *)(THREAD_START_SP + task_stack_page(p)) - 1)
diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 0e2d305..96f577e 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -276,13 +276,11 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
return 0;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
struct stackframe frame;
unsigned long stack_page;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
frame.fp = thread_saved_fp(p);
frame.sp = thread_saved_sp(p);
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index ee2bdc1..55ca034 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -257,7 +257,7 @@ struct task_struct;
/* Free all resources held by a thread. */
extern void release_thread(struct task_struct *);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
void update_sctlr_el1(u64 sctlr);
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 40adb8c..aacf2f5 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -528,13 +528,11 @@ __notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,
return last;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
struct stackframe frame;
unsigned long stack_page, ret = 0;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
stack_page = (unsigned long)try_get_task_stack(p);
if (!stack_page)
diff --git a/arch/csky/include/asm/processor.h b/arch/csky/include/asm/processor.h
index 9e93302..817dd60 100644
--- a/arch/csky/include/asm/processor.h
+++ b/arch/csky/include/asm/processor.h
@@ -81,7 +81,7 @@ static inline void release_thread(struct task_struct *dead_task)
extern int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
#define KSTK_ESP(tsk) (task_pt_regs(tsk)->usp)
diff --git a/arch/csky/kernel/stacktrace.c b/arch/csky/kernel/stacktrace.c
index 1b280ef..9f78f5d 100644
--- a/arch/csky/kernel/stacktrace.c
+++ b/arch/csky/kernel/stacktrace.c
@@ -111,12 +111,11 @@ static bool save_wchan(unsigned long pc, void *arg)
return false;
}
-unsigned long get_wchan(struct task_struct *task)
+unsigned long __get_wchan(struct task_struct *task)
{
unsigned long pc = 0;
- if (likely(task && task != current && !task_is_running(task)))
- walk_stackframe(task, NULL, save_wchan, &pc);
+ walk_stackframe(task, NULL, save_wchan, &pc);
return pc;
}
diff --git a/arch/h8300/include/asm/processor.h b/arch/h8300/include/asm/processor.h
index a060b41..141a23e 100644
--- a/arch/h8300/include/asm/processor.h
+++ b/arch/h8300/include/asm/processor.h
@@ -105,7 +105,7 @@ static inline void release_thread(struct task_struct *dead_task)
{
}
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) \
({ \
diff --git a/arch/h8300/kernel/process.c b/arch/h8300/kernel/process.c
index 2ac27e4..8833fa4 100644
--- a/arch/h8300/kernel/process.c
+++ b/arch/h8300/kernel/process.c
@@ -128,15 +128,12 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
return 0;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long fp, pc;
unsigned long stack_page;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
stack_page = (unsigned long)p;
fp = ((struct pt_regs *)p->thread.ksp)->er6;
do {
diff --git a/arch/hexagon/include/asm/processor.h b/arch/hexagon/include/asm/processor.h
index 9f0cc99..615f7e4 100644
--- a/arch/hexagon/include/asm/processor.h
+++ b/arch/hexagon/include/asm/processor.h
@@ -64,7 +64,7 @@ struct thread_struct {
extern void release_thread(struct task_struct *dead_task);
/* Get wait channel for task P. */
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
/* The following stuff is pretty HEXAGON specific. */
diff --git a/arch/hexagon/kernel/process.c b/arch/hexagon/kernel/process.c
index 6a6835f..232dfd8 100644
--- a/arch/hexagon/kernel/process.c
+++ b/arch/hexagon/kernel/process.c
@@ -130,13 +130,11 @@ void flush_thread(void)
* is an identification of the point at which the scheduler
* was invoked by a blocked thread.
*/
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long fp, pc;
unsigned long stack_page;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
stack_page = (unsigned long)task_stack_page(p);
fp = ((struct hexagon_switch_stack *)p->thread.switch_sp)->fp;
diff --git a/arch/ia64/include/asm/processor.h b/arch/ia64/include/asm/processor.h
index 2d8bcdc..45365c2 100644
--- a/arch/ia64/include/asm/processor.h
+++ b/arch/ia64/include/asm/processor.h
@@ -330,7 +330,7 @@ struct task_struct;
#define release_thread(dead_task)
/* Get wait channel for task P. */
-extern unsigned long get_wchan (struct task_struct *p);
+extern unsigned long __get_wchan (struct task_struct *p);
/* Return instruction pointer of blocked task TSK. */
#define KSTK_EIP(tsk) \
diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
index e56d63f..834df24 100644
--- a/arch/ia64/kernel/process.c
+++ b/arch/ia64/kernel/process.c
@@ -523,15 +523,12 @@ exit_thread (struct task_struct *tsk)
}
unsigned long
-get_wchan (struct task_struct *p)
+__get_wchan (struct task_struct *p)
{
struct unw_frame_info info;
unsigned long ip;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
/*
* Note: p may not be a blocked task (it could be current or
* another process running on some other CPU. Rather than
diff --git a/arch/m68k/include/asm/processor.h b/arch/m68k/include/asm/processor.h
index f4d82c6..ffeda9a 100644
--- a/arch/m68k/include/asm/processor.h
+++ b/arch/m68k/include/asm/processor.h
@@ -150,7 +150,7 @@ static inline void release_thread(struct task_struct *dead_task)
{
}
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) \
({ \
diff --git a/arch/m68k/kernel/process.c b/arch/m68k/kernel/process.c
index 1ab692b..a6030db 100644
--- a/arch/m68k/kernel/process.c
+++ b/arch/m68k/kernel/process.c
@@ -263,13 +263,11 @@ int dump_fpu (struct pt_regs *regs, struct user_m68kfp_struct *fpu)
}
EXPORT_SYMBOL(dump_fpu);
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long fp, pc;
unsigned long stack_page;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
stack_page = (unsigned long)task_stack_page(p);
fp = ((struct switch_stack *)p->thread.ksp)->a6;
diff --git a/arch/microblaze/include/asm/processor.h b/arch/microblaze/include/asm/processor.h
index 06c6e49..7e9e926 100644
--- a/arch/microblaze/include/asm/processor.h
+++ b/arch/microblaze/include/asm/processor.h
@@ -68,7 +68,7 @@ static inline void release_thread(struct task_struct *dead_task)
{
}
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
/* The size allocated for kernel stacks. This _must_ be a power of two! */
# define KERNEL_STACK_SIZE 0x2000
diff --git a/arch/microblaze/kernel/process.c b/arch/microblaze/kernel/process.c
index 62aa237..5e2b91c 100644
--- a/arch/microblaze/kernel/process.c
+++ b/arch/microblaze/kernel/process.c
@@ -112,7 +112,7 @@ int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg,
return 0;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
/* TBD (used by procfs) */
return 0;
diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h
index 0c3550c..252ed38 100644
--- a/arch/mips/include/asm/processor.h
+++ b/arch/mips/include/asm/processor.h
@@ -369,7 +369,7 @@ static inline void flush_thread(void)
{
}
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define __KSTK_TOS(tsk) ((unsigned long)task_stack_page(tsk) + \
THREAD_SIZE - 32 - sizeof(struct pt_regs))
diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 95aa86f..cbff1b9 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -511,7 +511,7 @@ static int __init frame_info_init(void)
/*
* Without schedule() frame info, result given by
- * thread_saved_pc() and get_wchan() are not reliable.
+ * thread_saved_pc() and __get_wchan() are not reliable.
*/
if (schedule_mfi.pc_offset < 0)
printk("Can't analyze schedule() prologue at %p\n", schedule);
@@ -652,9 +652,9 @@ unsigned long unwind_stack(struct task_struct *task, unsigned long *sp,
#endif
/*
- * get_wchan - a maintenance nightmare^W^Wpain in the ass ...
+ * __get_wchan - a maintenance nightmare^W^Wpain in the ass ...
*/
-unsigned long get_wchan(struct task_struct *task)
+unsigned long __get_wchan(struct task_struct *task)
{
unsigned long pc = 0;
#ifdef CONFIG_KALLSYMS
@@ -662,8 +662,6 @@ unsigned long get_wchan(struct task_struct *task)
unsigned long ra = 0;
#endif
- if (!task || task == current || task_is_running(task))
- goto out;
if (!task_stack_page(task))
goto out;
diff --git a/arch/nds32/include/asm/processor.h b/arch/nds32/include/asm/processor.h
index b82369c..e6bfc74 100644
--- a/arch/nds32/include/asm/processor.h
+++ b/arch/nds32/include/asm/processor.h
@@ -83,7 +83,7 @@ extern struct task_struct *last_task_used_math;
/* Prepare to copy thread state - unlazy all lazy status */
#define prepare_to_copy(tsk) do { } while (0)
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define cpu_relax() barrier()
diff --git a/arch/nds32/kernel/process.c b/arch/nds32/kernel/process.c
index 391895b..49fab9e 100644
--- a/arch/nds32/kernel/process.c
+++ b/arch/nds32/kernel/process.c
@@ -233,15 +233,12 @@ int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
EXPORT_SYMBOL(dump_fpu);
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long fp, lr;
unsigned long stack_start, stack_end;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
if (IS_ENABLED(CONFIG_FRAME_POINTER)) {
stack_start = (unsigned long)end_of_stack(p);
stack_end = (unsigned long)task_stack_page(p) + THREAD_SIZE;
@@ -258,5 +255,3 @@ unsigned long get_wchan(struct task_struct *p)
}
return 0;
}
-
-EXPORT_SYMBOL(get_wchan);
diff --git a/arch/nios2/include/asm/processor.h b/arch/nios2/include/asm/processor.h
index 94bcb86..b8125df 100644
--- a/arch/nios2/include/asm/processor.h
+++ b/arch/nios2/include/asm/processor.h
@@ -69,7 +69,7 @@ static inline void release_thread(struct task_struct *dead_task)
{
}
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
#define task_pt_regs(p) \
((struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1)
diff --git a/arch/nios2/kernel/process.c b/arch/nios2/kernel/process.c
index 9ff37ba..f8ea522 100644
--- a/arch/nios2/kernel/process.c
+++ b/arch/nios2/kernel/process.c
@@ -217,15 +217,12 @@ void dump(struct pt_regs *fp)
pr_emerg("\n\n");
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long fp, pc;
unsigned long stack_page;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
stack_page = (unsigned long)p;
fp = ((struct switch_stack *)p->thread.ksp)->fp; /* ;dgt2 */
do {
diff --git a/arch/openrisc/include/asm/processor.h b/arch/openrisc/include/asm/processor.h
index ad53b31..aa1699c 100644
--- a/arch/openrisc/include/asm/processor.h
+++ b/arch/openrisc/include/asm/processor.h
@@ -73,7 +73,7 @@ struct thread_struct {
void start_thread(struct pt_regs *regs, unsigned long nip, unsigned long sp);
void release_thread(struct task_struct *);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define cpu_relax() barrier()
diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
index b0698d9..3c0c91b 100644
--- a/arch/openrisc/kernel/process.c
+++ b/arch/openrisc/kernel/process.c
@@ -263,7 +263,7 @@ void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
dest[35] = 0;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
/* TODO */
diff --git a/arch/parisc/include/asm/processor.h b/arch/parisc/include/asm/processor.h
index eeb7da0..85a2dbf 100644
--- a/arch/parisc/include/asm/processor.h
+++ b/arch/parisc/include/asm/processor.h
@@ -273,7 +273,7 @@ struct mm_struct;
/* Free all resources held by a thread. */
extern void release_thread(struct task_struct *);
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) ((tsk)->thread.regs.iaoq[0])
#define KSTK_ESP(tsk) ((tsk)->thread.regs.gr[30])
diff --git a/arch/parisc/kernel/process.c b/arch/parisc/kernel/process.c
index 38ec4ae..4f562de 100644
--- a/arch/parisc/kernel/process.c
+++ b/arch/parisc/kernel/process.c
@@ -240,15 +240,12 @@ copy_thread(unsigned long clone_flags, unsigned long usp,
}
unsigned long
-get_wchan(struct task_struct *p)
+__get_wchan(struct task_struct *p)
{
struct unwind_frame_info info;
unsigned long ip;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
/*
* These bracket the sleeping functions..
*/
diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
index f348e56..e39bd0f 100644
--- a/arch/powerpc/include/asm/processor.h
+++ b/arch/powerpc/include/asm/processor.h
@@ -300,7 +300,7 @@ struct thread_struct {
#define task_pt_regs(tsk) ((tsk)->thread.regs)
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) ((tsk)->thread.regs? (tsk)->thread.regs->nip: 0)
#define KSTK_ESP(tsk) ((tsk)->thread.regs? (tsk)->thread.regs->gpr[1]: 0)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 50436b5..406d7ee 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -2111,14 +2111,11 @@ int validate_sp(unsigned long sp, struct task_struct *p,
EXPORT_SYMBOL(validate_sp);
-static unsigned long __get_wchan(struct task_struct *p)
+static unsigned long ___get_wchan(struct task_struct *p)
{
unsigned long ip, sp;
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
sp = p->thread.ksp;
if (!validate_sp(sp, p, STACK_FRAME_OVERHEAD))
return 0;
@@ -2137,14 +2134,14 @@ static unsigned long __get_wchan(struct task_struct *p)
return 0;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long ret;
if (!try_get_task_stack(p))
return 0;
- ret = __get_wchan(p);
+ ret = ___get_wchan(p);
put_task_stack(p);
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index 46b492c..0749924 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -66,7 +66,7 @@ static inline void release_thread(struct task_struct *dead_task)
{
}
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
static inline void wait_for_interrupt(void)
diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
index 315db3d..0fcdc02 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -128,16 +128,14 @@ static bool save_wchan(void *arg, unsigned long pc)
return true;
}
-unsigned long get_wchan(struct task_struct *task)
+unsigned long __get_wchan(struct task_struct *task)
{
unsigned long pc = 0;
- if (likely(task && task != current && !task_is_running(task))) {
- if (!try_get_task_stack(task))
- return 0;
- walk_stackframe(task, NULL, save_wchan, &pc);
- put_task_stack(task);
- }
+ if (!try_get_task_stack(task))
+ return 0;
+ walk_stackframe(task, NULL, save_wchan, &pc);
+ put_task_stack(task);
return pc;
}
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 879b8e3..f54c152 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -192,7 +192,7 @@ static inline void release_thread(struct task_struct *tsk) { }
void guarded_storage_release(struct task_struct *tsk);
void gs_load_bc_cb(struct pt_regs *regs);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
#define task_pt_regs(tsk) ((struct pt_regs *) \
(task_stack_page(tsk) + THREAD_SIZE) - 1)
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->psw.addr)
diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 350e94d..e5dd46b 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -181,12 +181,12 @@ void execve_tail(void)
asm volatile("sfpc %0" : : "d" (0));
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
struct unwind_state state;
unsigned long ip = 0;
- if (!p || p == current || task_is_running(p) || !task_stack_page(p))
+ if (!task_stack_page(p))
return 0;
if (!try_get_task_stack(p))
diff --git a/arch/sh/include/asm/processor_32.h b/arch/sh/include/asm/processor_32.h
index aa92cc9..45240ec 100644
--- a/arch/sh/include/asm/processor_32.h
+++ b/arch/sh/include/asm/processor_32.h
@@ -180,7 +180,7 @@ static inline void show_code(struct pt_regs *regs)
}
#endif
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
#define KSTK_ESP(tsk) (task_pt_regs(tsk)->regs[15])
diff --git a/arch/sh/kernel/process_32.c b/arch/sh/kernel/process_32.c
index 717de05..1c28e3c 100644
--- a/arch/sh/kernel/process_32.c
+++ b/arch/sh/kernel/process_32.c
@@ -182,13 +182,10 @@ __switch_to(struct task_struct *prev, struct task_struct *next)
return prev;
}
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long pc;
- if (!p || p == current || task_is_running(p))
- return 0;
-
/*
* The same comment as on the Alpha applies here, too ...
*/
diff --git a/arch/sparc/include/asm/processor_32.h b/arch/sparc/include/asm/processor_32.h
index b6242f7..647bf0a 100644
--- a/arch/sparc/include/asm/processor_32.h
+++ b/arch/sparc/include/asm/processor_32.h
@@ -89,7 +89,7 @@ static inline void start_thread(struct pt_regs * regs, unsigned long pc,
/* Free all resources held by a thread. */
#define release_thread(tsk) do { } while(0)
-unsigned long get_wchan(struct task_struct *);
+unsigned long __get_wchan(struct task_struct *);
#define task_pt_regs(tsk) ((tsk)->thread.kregs)
#define KSTK_EIP(tsk) ((tsk)->thread.kregs->pc)
diff --git a/arch/sparc/include/asm/processor_64.h b/arch/sparc/include/asm/processor_64.h
index 5cf145f..ae851e8 100644
--- a/arch/sparc/include/asm/processor_64.h
+++ b/arch/sparc/include/asm/processor_64.h
@@ -183,7 +183,7 @@ do { \
/* Free all resources held by a thread. */
#define release_thread(tsk) do { } while (0)
-unsigned long get_wchan(struct task_struct *task);
+unsigned long __get_wchan(struct task_struct *task);
#define task_pt_regs(tsk) (task_thread_info(tsk)->kregs)
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->tpc)
diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c
index bbbe0cf..2dc0bf9 100644
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -365,7 +365,7 @@ int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg,
return 0;
}
-unsigned long get_wchan(struct task_struct *task)
+unsigned long __get_wchan(struct task_struct *task)
{
unsigned long pc, fp, bias = 0;
unsigned long task_base = (unsigned long) task;
@@ -373,9 +373,6 @@ unsigned long get_wchan(struct task_struct *task)
struct reg_window32 *rw;
int count = 0;
- if (!task || task == current || task_is_running(task))
- goto out;
-
fp = task_thread_info(task)->ksp + bias;
do {
/* Bogus frame pointer? */
diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index d1cc410..f5b2cac 100644
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -663,7 +663,7 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
return 0;
}
-unsigned long get_wchan(struct task_struct *task)
+unsigned long __get_wchan(struct task_struct *task)
{
unsigned long pc, fp, bias = 0;
struct thread_info *tp;
@@ -671,9 +671,6 @@ unsigned long get_wchan(struct task_struct *task)
unsigned long ret = 0;
int count = 0;
- if (!task || task == current || task_is_running(task))
- goto out;
-
tp = task_thread_info(task);
bias = STACK_BIAS;
fp = task_thread_info(task)->ksp + bias;
diff --git a/arch/um/include/asm/processor-generic.h b/arch/um/include/asm/processor-generic.h
index b5cf0ed..579692a 100644
--- a/arch/um/include/asm/processor-generic.h
+++ b/arch/um/include/asm/processor-generic.h
@@ -106,6 +106,6 @@ extern struct cpuinfo_um boot_cpu_data;
#define cache_line_size() (boot_cpu_data.cache_alignment)
#define KSTK_REG(tsk, reg) get_thread_reg(reg, &tsk->thread.switch_buf)
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
#endif
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 457a38d..8210737 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -364,14 +364,11 @@ unsigned long arch_align_stack(unsigned long sp)
}
#endif
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long stack_page, sp, ip;
bool seen_sched = 0;
- if ((p == NULL) || (p == current) || task_is_running(p))
- return 0;
-
stack_page = (unsigned long) task_stack_page(p);
/* Bail if the process has no kernel stack for some reason */
if (stack_page == 0)
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 9ad2aca..e81177e 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -589,7 +589,7 @@ static inline void load_sp0(unsigned long sp0)
/* Free all resources held by a thread. */
extern void release_thread(struct task_struct *);
-unsigned long get_wchan(struct task_struct *p);
+unsigned long __get_wchan(struct task_struct *p);
/*
* Generic CPUID function
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index e645925..a69885a 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -942,13 +942,10 @@ unsigned long arch_randomize_brk(struct mm_struct *mm)
* because the task might wake up and we might look at a stack
* changing under us.
*/
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long entry = 0;
- if (p == current || task_is_running(p))
- return 0;
-
stack_trace_save_tsk(p, &entry, 1, 0);
return entry;
}
diff --git a/arch/xtensa/include/asm/processor.h b/arch/xtensa/include/asm/processor.h
index 7f63aca..ad15fbc 100644
--- a/arch/xtensa/include/asm/processor.h
+++ b/arch/xtensa/include/asm/processor.h
@@ -215,7 +215,7 @@ struct mm_struct;
/* Free all resources held by a thread. */
#define release_thread(thread) do { } while(0)
-extern unsigned long get_wchan(struct task_struct *p);
+extern unsigned long __get_wchan(struct task_struct *p);
#define KSTK_EIP(tsk) (task_pt_regs(tsk)->pc)
#define KSTK_ESP(tsk) (task_pt_regs(tsk)->areg[1])
diff --git a/arch/xtensa/kernel/process.c b/arch/xtensa/kernel/process.c
index 0601653..47f933f 100644
--- a/arch/xtensa/kernel/process.c
+++ b/arch/xtensa/kernel/process.c
@@ -298,15 +298,12 @@ int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
* These bracket the sleeping functions..
*/
-unsigned long get_wchan(struct task_struct *p)
+unsigned long __get_wchan(struct task_struct *p)
{
unsigned long sp, pc;
unsigned long stack_page = (unsigned long) task_stack_page(p);
int count = 0;
- if (!p || p == current || task_is_running(p))
- return 0;
-
sp = p->thread.sp;
pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 343603f..5f8db54 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2139,6 +2139,7 @@ static inline void set_task_cpu(struct task_struct *p, unsigned int cpu)
#endif /* CONFIG_SMP */
extern bool sched_task_on_rq(struct task_struct *p);
+extern unsigned long get_wchan(struct task_struct *p);
/*
* In order to reduce various lock holder preemption latencies provide an
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 935c2da..f2611b9 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1966,6 +1966,25 @@ bool sched_task_on_rq(struct task_struct *p)
return task_on_rq_queued(p);
}
+unsigned long get_wchan(struct task_struct *p)
+{
+ unsigned long ip = 0;
+ unsigned int state;
+
+ if (!p || p == current)
+ return 0;
+
+ /* Only get wchan if task is blocked and we can keep it that way. */
+ raw_spin_lock_irq(&p->pi_lock);
+ state = READ_ONCE(p->__state);
+ smp_rmb(); /* see try_to_wake_up() */
+ if (state != TASK_RUNNING && state != TASK_WAKING && !p->on_rq)
+ ip = __get_wchan(p);
+ raw_spin_unlock_irq(&p->pi_lock);
+
+ return ip;
+}
+
static inline void enqueue_task(struct rq *rq, struct task_struct *p, int flags)
{
if (!(flags & ENQUEUE_NOCLOCK))