Re: [PATCH v4 1/3] stacktrace: Remove weak version of save_stack_trace_tsk_reliable()

Re: [PATCH v4 1/3] stacktrace: Remove weak version of save_stack_trace_tsk_reliable()

[Petr Mladek]

Hi Thomas,

On Sun 2019-06-16 10:44:59, Thomas Gleixner wrote:
> On Tue, 11 Jun 2019, Miroslav Benes wrote:
> 
> > Recent rework of stack trace infrastructure introduced a new set of
> > helpers for common stack trace operations (commit e9b98e162aa5
> > ("stacktrace: Provide helpers for common stack trace operations") and
> > related). As a result, save_stack_trace_tsk_reliable() is not directly
> > called anywhere. Livepatch, currently the only user of the reliable
> > stack trace feature, now calls stack_trace_save_tsk_reliable().
> > 
> > When CONFIG_HAVE_RELIABLE_STACKTRACE is set and depending on
> > CONFIG_ARCH_STACKWALK, stack_trace_save_tsk_reliable() calls either
> > arch_stack_walk_reliable() or mentioned save_stack_trace_tsk_reliable().
> > x86_64 defines the former, ppc64le the latter. All other architectures
> > do not have HAVE_RELIABLE_STACKTRACE and include/linux/stacktrace.h
> > defines -ENOSYS returning version for them.
> > 
> > In short, stack_trace_save_tsk_reliable() returning -ENOSYS defined in
> > include/linux/stacktrace.h serves the same purpose as the old weak
> > version of save_stack_trace_tsk_reliable() which is therefore no longer
> > needed.
> > 
> > Cc: Thomas Gleixner <tglx@linutronix.de>
> > Signed-off-by: Miroslav Benes <mbenes@suse.cz>
> 
> Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

Would you like to push this patch via your tree?
Or is it OK to push it via the livepatch tree for 5.3?

Best Regards,
Petr

Re: [PATCH v4 1/3] stacktrace: Remove weak version of save_stack_trace_tsk_reliable()

[Thomas Gleixner]

On Mon, 17 Jun 2019, Petr Mladek wrote:
> On Sun 2019-06-16 10:44:59, Thomas Gleixner wrote:
> > On Tue, 11 Jun 2019, Miroslav Benes wrote:
> > 
> > > Recent rework of stack trace infrastructure introduced a new set of
> > > helpers for common stack trace operations (commit e9b98e162aa5
> > > ("stacktrace: Provide helpers for common stack trace operations") and
> > > related). As a result, save_stack_trace_tsk_reliable() is not directly
> > > called anywhere. Livepatch, currently the only user of the reliable
> > > stack trace feature, now calls stack_trace_save_tsk_reliable().
> > > Cc: Thomas Gleixner <tglx@linutronix.de>
> > > Signed-off-by: Miroslav Benes <mbenes@suse.cz>
> > 
> > Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
> 
> Would you like to push this patch via your tree?
> Or is it OK to push it via the livepatch tree for 5.3?

Just pick it up. I don't think we have anything conflicting.

Thanks,

	tglx

Re: [PATCH v4 0/3] livepatch: Cleanup of reliable stacktrace warnings

[Petr Mladek]

On Sat 2019-06-15 15:43:20, Josh Poimboeuf wrote:
> On Tue, Jun 11, 2019 at 04:13:17PM +0200, Miroslav Benes wrote:
> > This is the fourth attempt to improve the situation of reliable stack
> > trace warnings in livepatch. Based on discussion in
> > 20190531074147.27616-1-pmladek@suse.com (v3).
> > 
> > Changes against v3:
> > + weak save_stack_trace_tsk_reliable() removed, because it is not needed
> >   anymore thanks to Thomas' recent improvements
> > + klp_have_reliable_stack() check reintroduced in klp_try_switch_task()
> > 
> > Changes against v2:
> > 
> > + Put back the patch removing WARN_ONCE in the weak
> >   save_stack_trace_tsk_reliable(). It is related.
> > + Simplified patch removing the duplicate warning from klp_check_stack()
> > + Update commit message for 3rd patch [Josh]
> > 
> > Miroslav Benes (2):
> >   stacktrace: Remove weak version of save_stack_trace_tsk_reliable()
> >   Revert "livepatch: Remove reliable stacktrace check in
> >     klp_try_switch_task()"
> > 
> > Petr Mladek (1):
> >   livepatch: Remove duplicate warning about missing reliable stacktrace
> >     support
> > 
> >  kernel/livepatch/transition.c | 8 +++++++-
> >  kernel/stacktrace.c           | 8 --------
> >  2 files changed, 7 insertions(+), 9 deletions(-)
> 
> Thanks Miroslav for wrapping this up, and thanks to Petr for his
> previous work on this.
> 
> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>

All three patches have been commited into for-5.3/core branch.

Best Regards,
Petr