Messages in this thread | | | Date | Tue, 1 May 2018 14:46:20 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH] tracing/irqtrace: only call trace_hardirqs_on/off when state changes |
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On Fri, 17 Nov 2017 02:15:06 +1000 Nicholas Piggin <npiggin@gmail.com> wrote:
> In local_irq_save and local_irq_restore, only call irq tracing when > the flag state acutally changes. It is not unexpected for the state > to go disable->disable. > > This allows the irq tracing code to better track superfluous > enables and disables, and in future could issue warnings. For the > most part they are harmless, but they can indicate that the caller > has lost track of its irq state.
I missed this before (that was a busy time, I missed a lot of emails then :-/ ).
Anyway, this makes sense.
Peter?
-- Steve
> > Cc: Steven Rostedt <rostedt@goodmis.org> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Nicholas Piggin <npiggin@gmail.com> > --- > I wonder what you think of this patch? After a small fix to > init/main.c and some powerpc fixes, I was able to use this patch > and a change to warn in the lockdep code in case of redundant ops, > to verify there were no local_irq_enable() when enabled, or > local_irq_disable() when disabled (which was implicated in a bug). > > Lots of code to verify so we can't do this immediately, but I > think it's cleaner to enforce the rule? > > Thanks, > Nick > > include/linux/irqflags.h | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h > index 46cb57d5eb13..82287e1c6c52 100644 > --- a/include/linux/irqflags.h > +++ b/include/linux/irqflags.h > @@ -110,7 +110,8 @@ do { \ > #define local_irq_save(flags) \ > do { \ > raw_local_irq_save(flags); \ > - trace_hardirqs_off(); \ > + if (!raw_irqs_disabled_flags(flags)) \ > + trace_hardirqs_off(); \ > } while (0) > > > @@ -118,9 +119,11 @@ do { \ > do { \ > if (raw_irqs_disabled_flags(flags)) { \ > raw_local_irq_restore(flags); \ > - trace_hardirqs_off(); \ > + if (!irqs_disabled()) \ > + trace_hardirqs_off(); \ > } else { \ > - trace_hardirqs_on(); \ > + if (irqs_disabled()) \ > + trace_hardirqs_on(); \ > raw_local_irq_restore(flags); \ > } \ > } while (0)
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