* Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> 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 <mingo@xxxxxxxxxx>
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 <sfr@xxxxxxxxxxxxxxxx>
Fixes: bc9bbb81730e ("x86: Fix get_wchan() to support the ORC unwinder")
Cc: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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,
