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SubjectRe: [PATCH] Support resetting WARN_ONCE for all architectures
Date
Andrew Morton <akpm@linux-foundation.org> writes:
> On Fri, 03 Nov 2017 20:38:03 +1100 Michael Ellerman <mpe@ellerman.id.au> wrote:
>> Andi Kleen <andi@firstfloor.org> writes:
>> > diff --git a/lib/bug.c b/lib/bug.c
>> > index a6a1137d06db..7cb2d41845f7 100644
>> > --- a/lib/bug.c
>> > +++ b/lib/bug.c
>> > @@ -195,3 +195,24 @@ enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs)
>> >
>> > return BUG_TRAP_TYPE_BUG;
>> > }
>> > +
>> > +static void clear_once_table(struct bug_entry *start, struct bug_entry *end)
>> > +{
>> > + struct bug_entry *bug;
>> > +
>> > + for (bug = start; bug < end; bug++)
>> > + bug->flags &= ~BUGFLAG_ONCE;
>>
>> Clearing BUGFLAG_ONCE removes the once-ness permanently. ie. it becomes
>> a WARN().
>>
>> You should be clearing BUGFLAG_DONE, which is the flag that says this
>> WARN has already triggered.
>
> This?

Yes.

> --- a/lib/bug.c~support-resetting-warn_once-for-all-architectures-v2-fix-fix-fix
> +++ a/lib/bug.c
> @@ -202,7 +202,7 @@ static void clear_once_table(struct bug_
> struct bug_entry *bug;
>
> for (bug = start; bug < end; bug++)
> - bug->flags &= ~BUGFLAG_ONCE;
> + bug->flags &= ~BUGFLAG_DONE;
> }
>
> void generic_bug_clear_once(void)
>
>
> And this is getting a bit nutty:
>
> support-resetting-warn_once.patch
> support-resetting-warn_once-checkpatch-fixes.patch
> support-resetting-warn_once-for-all-architectures.patch
> support-resetting-warn_once-for-all-architectures-v2.patch
> support-resetting-warn_once-for-all-architectures-v2-fix.patch
> support-resetting-warn_once-for-all-architectures-v2-fix-fix.patch
> support-resetting-warn_once-for-all-architectures-v2-fix-fix-fix.patch

Quite. They should probably all just be squashed together.

> I'll push all this at Stephen later today. Someone please tell me
> whether this code actually works!

I've tested Andi's two patches with the above one-liner and that worked
for me. I'll test again on linux-next once it's in there to confirm.

cheers

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