Hi,
I split this up into 3 pieces instead of the messy single patch, hope
this helps with review.
Patch 1 adds task_sigpending(), which tests TIF_SIGPENDING. Core use
cases that need to check for an actual signal pending are switched to
using task_sigpending() instead of signal_pending(). This should fix
Oleg's concern on signal_pending() == true, but no signals pending,
for actual signal delivery.
Patch 2 adds x86 and generic entry code support for TIF_TASKWORK.
Patch 3 adds task_work support for TIF_TASKWORK, if the arch supports it.
There's no need for any io_uring specific changes, so I've dropped those.
If TIF_TASKWORK is used, then JOBCTL_TASK_WORK will never be true and
hence we won't enter that case. If TIF_TASKWORK isn't available, then
we still need that code.
I've run this through my usual liburing test, and it passes. I also ran
it through all the ltp signal testing, and no changes from mainline in
terms of all tests passing.
arch/x86/include/asm/thread_info.h | 2 ++
arch/x86/kernel/signal.c | 32 +++++++++++---------
include/linux/entry-common.h | 20 +++++++++++--
include/linux/sched/signal.h | 32 ++++++++++++++++----
kernel/entry/common.c | 14 +++++++--
kernel/events/uprobes.c | 2 +-
kernel/ptrace.c | 2 +-
kernel/signal.c | 12 ++++----
kernel/task_work.c | 48 ++++++++++++++++++++++--------
9 files changed, 118 insertions(+), 46 deletions(-)
Changes can also be viewed/pulled from this branch:
git://git.kernel.dk/linux-block tif-task_work
https://git.kernel.dk/cgit/linux-block/log/?h=tif-task_work
--
Jens Axboe
This is in preparation for maintaining signal_pending() as the decider
of whether or not a schedule() loop should be broken, or continue
sleeping. This is different than the core signal use cases, where we
really want to know if an actual signal is pending or not.
task_sigpending() returns non-zero if TIF_SIGPENDING is set.
Only core kernel use cases should care about the distinction between
the two, make sure those use the task_sigpending() helper.
Signed-off-by: Jens Axboe <[email protected]>
---
include/linux/sched/signal.h | 13 +++++++++----
kernel/events/uprobes.c | 2 +-
kernel/ptrace.c | 2 +-
kernel/signal.c | 12 ++++++------
4 files changed, 17 insertions(+), 12 deletions(-)
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 1bad18a1d8ba..e6f34d8fbf4d 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -353,11 +353,16 @@ static inline int restart_syscall(void)
return -ERESTARTNOINTR;
}
-static inline int signal_pending(struct task_struct *p)
+static inline int task_sigpending(struct task_struct *p)
{
return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
}
+static inline int signal_pending(struct task_struct *p)
+{
+ return task_sigpending(p);
+}
+
static inline int __fatal_signal_pending(struct task_struct *p)
{
return unlikely(sigismember(&p->pending.signal, SIGKILL));
@@ -365,14 +370,14 @@ static inline int __fatal_signal_pending(struct task_struct *p)
static inline int fatal_signal_pending(struct task_struct *p)
{
- return signal_pending(p) && __fatal_signal_pending(p);
+ return task_sigpending(p) && __fatal_signal_pending(p);
}
static inline int signal_pending_state(long state, struct task_struct *p)
{
if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
return 0;
- if (!signal_pending(p))
+ if (!task_sigpending(p))
return 0;
return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
@@ -389,7 +394,7 @@ static inline bool fault_signal_pending(vm_fault_t fault_flags,
{
return unlikely((fault_flags & VM_FAULT_RETRY) &&
(fatal_signal_pending(current) ||
- (user_mode(regs) && signal_pending(current))));
+ (user_mode(regs) && task_sigpending(current))));
}
/*
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 0e18aaf23a7b..8bb26a338e06 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1973,7 +1973,7 @@ bool uprobe_deny_signal(void)
WARN_ON_ONCE(utask->state != UTASK_SSTEP);
- if (signal_pending(t)) {
+ if (task_sigpending(t)) {
spin_lock_irq(&t->sighand->siglock);
clear_tsk_thread_flag(t, TIF_SIGPENDING);
spin_unlock_irq(&t->sighand->siglock);
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 43d6179508d6..583b8da4c207 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -773,7 +773,7 @@ static int ptrace_peek_siginfo(struct task_struct *child,
data += sizeof(siginfo_t);
i++;
- if (signal_pending(current))
+ if (task_sigpending(current))
break;
cond_resched();
diff --git a/kernel/signal.c b/kernel/signal.c
index a38b3edc6851..ad52141ab0d2 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -983,7 +983,7 @@ static inline bool wants_signal(int sig, struct task_struct *p)
if (task_is_stopped_or_traced(p))
return false;
- return task_curr(p) || !signal_pending(p);
+ return task_curr(p) || !task_sigpending(p);
}
static void complete_signal(int sig, struct task_struct *p, enum pid_type type)
@@ -2822,7 +2822,7 @@ static void retarget_shared_pending(struct task_struct *tsk, sigset_t *which)
/* Remove the signals this thread can handle. */
sigandsets(&retarget, &retarget, &t->blocked);
- if (!signal_pending(t))
+ if (!task_sigpending(t))
signal_wake_up(t, 0);
if (sigisemptyset(&retarget))
@@ -2856,7 +2856,7 @@ void exit_signals(struct task_struct *tsk)
cgroup_threadgroup_change_end(tsk);
- if (!signal_pending(tsk))
+ if (!task_sigpending(tsk))
goto out;
unblocked = tsk->blocked;
@@ -2900,7 +2900,7 @@ long do_no_restart_syscall(struct restart_block *param)
static void __set_task_blocked(struct task_struct *tsk, const sigset_t *newset)
{
- if (signal_pending(tsk) && !thread_group_empty(tsk)) {
+ if (task_sigpending(tsk) && !thread_group_empty(tsk)) {
sigset_t newblocked;
/* A set of now blocked but previously unblocked signals. */
sigandnsets(&newblocked, newset, ¤t->blocked);
@@ -4443,7 +4443,7 @@ SYSCALL_DEFINE2(signal, int, sig, __sighandler_t, handler)
SYSCALL_DEFINE0(pause)
{
- while (!signal_pending(current)) {
+ while (!task_sigpending(current)) {
__set_current_state(TASK_INTERRUPTIBLE);
schedule();
}
@@ -4457,7 +4457,7 @@ static int sigsuspend(sigset_t *set)
current->saved_sigmask = current->blocked;
set_current_blocked(set);
- while (!signal_pending(current)) {
+ while (!task_sigpending(current)) {
__set_current_state(TASK_INTERRUPTIBLE);
schedule();
}
--
2.28.0