Hi all,
After merging the tip tree, today's linux-next build (x86_64 allnoconfig)
failed like this:
arch/x86/kernel/process.c: In function '__get_wchan':
arch/x86/kernel/process.c:950:2: error: implicit declaration of function 'stack_trace_save_tsk' [-Werror=implicit-function-declaration]
950 | stack_trace_save_tsk(p, &entry, 1, 0);
| ^~~~~~~~~~~~~~~~~~~~
cc1: some warnings being treated as errors
Caused by commit
bc9bbb81730e ("x86: Fix get_wchan() to support the ORC unwinder")
stack_trace_save_tsk() requires CONFIG_STACKTRACE which is not set for
this build.
I have reverted that commit, and commit
42a20f86dc19 ("sched: Add wrapper for get_wchan() to keep task blocked")
which follows it, for today.
--
Cheers,
Stephen Rothwell
On 10/18/21 2:23 PM, Stephen Rothwell wrote:
> Hi all,
>
> After merging the tip tree, today's linux-next build (x86_64 allnoconfig)
> failed like this:
>
> arch/x86/kernel/process.c: In function '__get_wchan':
> arch/x86/kernel/process.c:950:2: error: implicit declaration of function 'stack_trace_save_tsk' [-Werror=implicit-function-declaration]
> 950 | stack_trace_save_tsk(p, &entry, 1, 0);
> | ^~~~~~~~~~~~~~~~~~~~
> cc1: some warnings being treated as errors
>
> Caused by commit
>
> bc9bbb81730e ("x86: Fix get_wchan() to support the ORC unwinder")
>
> stack_trace_save_tsk() requires CONFIG_STACKTRACE which is not set for
> this build.
Maybe get_wchan() can be updated to:
unsigned long get_wchan(struct task_struct *p)
{
#ifdef CONFIG_STACKTRACE
unsigned long entry = 0;
stack_trace_save_tsk(p, &entry, 1, 0);
return entry;
#else /* CONFIG_STACKTRACE */
return 0;
#endif
}
Thanks,
Qi
>
> I have reverted that commit, and commit
>
> 42a20f86dc19 ("sched: Add wrapper for get_wchan() to keep task blocked")
>
> which follows it, for today.
>
* Qi Zheng <[email protected]> wrote:
>
>
> On 10/18/21 2:23 PM, Stephen Rothwell wrote:
> > Hi all,
> >
> > After merging the tip tree, today's linux-next build (x86_64 allnoconfig)
> > failed like this:
> >
> > arch/x86/kernel/process.c: In function '__get_wchan':
> > arch/x86/kernel/process.c:950:2: error: implicit declaration of function 'stack_trace_save_tsk' [-Werror=implicit-function-declaration]
> > 950 | stack_trace_save_tsk(p, &entry, 1, 0);
> > | ^~~~~~~~~~~~~~~~~~~~
> > cc1: some warnings being treated as errors
> >
> > Caused by commit
> >
> > bc9bbb81730e ("x86: Fix get_wchan() to support the ORC unwinder")
> >
> > stack_trace_save_tsk() requires CONFIG_STACKTRACE which is not set for
> > this build.
>
> Maybe get_wchan() can be updated to:
>
> unsigned long get_wchan(struct task_struct *p)
> {
> #ifdef CONFIG_STACKTRACE
> unsigned long entry = 0;
>
> stack_trace_save_tsk(p, &entry, 1, 0);
> return entry;
> #else /* CONFIG_STACKTRACE */
> return 0;
> #endif
> }
And repeat the same ugliness in every single function that happens to use
the stack_trace_save_tsk() API??
The correct solution is to define stack_trace_save_tsk() in the
!CONFIG_STACKTRACE case too, as the patch below does.
Thanks,
Ingo
==============================>
From: Ingo Molnar <[email protected]>
Date: Fri, 22 Oct 2021 09:40:27 +0200
Subject: [PATCH] stacktrace: Provide stack_trace_save_tsk() stub in the !CONFIG_STACKTRACE case too
The following commit:
bc9bbb81730e ("x86: Fix get_wchan() to support the ORC unwinder")
Added stack_trace_save_tsk() use to __get_wchan(), while this method is not
unconditionally defined: it's not available in the !CONFIG_STACKTRACE case.
Give a default implementation that does nothing.
Reported-by: Stephen Rothwell <[email protected]>
Fixes: bc9bbb81730e ("x86: Fix get_wchan() to support the ORC unwinder")
Cc: Qi Zheng <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Signed-off-by: Ingo Molnar <[email protected]>
---
include/linux/stacktrace.h | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/include/linux/stacktrace.h b/include/linux/stacktrace.h
index 9edecb494e9e..3ccaf599630f 100644
--- a/include/linux/stacktrace.h
+++ b/include/linux/stacktrace.h
@@ -91,8 +91,19 @@ extern void save_stack_trace_tsk(struct task_struct *tsk,
extern int save_stack_trace_tsk_reliable(struct task_struct *tsk,
struct stack_trace *trace);
extern void save_stack_trace_user(struct stack_trace *trace);
+
#endif /* !CONFIG_ARCH_STACKWALK */
-#endif /* CONFIG_STACKTRACE */
+
+#else /* !CONFIG_STACKTRACE: */
+static inline unsigned int
+stack_trace_save_tsk(struct task_struct *task,
+ unsigned long *store, unsigned int size,
+ unsigned int skipnr)
+{
+ return -ENOSYS;
+}
+
+#endif /* !CONFIG_STACKTRACE */
#if defined(CONFIG_STACKTRACE) && defined(CONFIG_HAVE_RELIABLE_STACKTRACE)
int stack_trace_save_tsk_reliable(struct task_struct *tsk, unsigned long *store,
On Fri, Oct 22, 2021 at 09:43:50AM +0200, Ingo Molnar wrote:
>
> * Qi Zheng <[email protected]> wrote:
>
> >
> >
> > On 10/18/21 2:23 PM, Stephen Rothwell wrote:
> > > Hi all,
> > >
> > > After merging the tip tree, today's linux-next build (x86_64 allnoconfig)
> > > failed like this:
> > >
> > > arch/x86/kernel/process.c: In function '__get_wchan':
> > > arch/x86/kernel/process.c:950:2: error: implicit declaration of function 'stack_trace_save_tsk' [-Werror=implicit-function-declaration]
> > > 950 | stack_trace_save_tsk(p, &entry, 1, 0);
> > > | ^~~~~~~~~~~~~~~~~~~~
> > > cc1: some warnings being treated as errors
> > >
> > > Caused by commit
> > >
> > > bc9bbb81730e ("x86: Fix get_wchan() to support the ORC unwinder")
> > >
> > > stack_trace_save_tsk() requires CONFIG_STACKTRACE which is not set for
> > > this build.
> >
> > Maybe get_wchan() can be updated to:
> >
> > unsigned long get_wchan(struct task_struct *p)
> > {
> > #ifdef CONFIG_STACKTRACE
> > unsigned long entry = 0;
> >
> > stack_trace_save_tsk(p, &entry, 1, 0);
> > return entry;
> > #else /* CONFIG_STACKTRACE */
> > return 0;
> > #endif
> > }
>
> And repeat the same ugliness in every single function that happens to use
> the stack_trace_save_tsk() API??
>
> The correct solution is to define stack_trace_save_tsk() in the
> !CONFIG_STACKTRACE case too, as the patch below does.
That doesn't make sense for x86. We have an unconditional unwinder
present.
I've got these, meant to post them later today:
https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/log/?h=sched/wchan