On Fri, Oct 22, 2021 at 09:43:50AM +0200, Ingo Molnar wrote:
>
> * 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.
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
