* [PATCH] preempt: add in_serving_irq() and apply to rcutiny and vsprintf @ 2021-08-14 1:42 Changbin Du 2021-08-16 16:03 ` Boqun Feng 0 siblings, 1 reply; 5+ messages in thread From: Changbin Du @ 2021-08-14 1:42 UTC (permalink / raw) To: Ingo Molnar, Peter Zijlstra, Juri Lelli Cc: Vincent Guittot, Dietmar Eggemann, Paul E. McKenney, Josh Triplett, Sergey Senozhatsky, linux-kernel, rcu, Changbin Du At some places we need to determine whether we're in nmi, hardirq or softirq context. This adds a macro in_serving_irq() as a shortcut for that. Meanwhile, apply this new macro to existing code in rcutiny and vsprintf. Signed-off-by: Changbin Du <changbin.du@gmail.com> --- include/linux/preempt.h | 4 +++- include/linux/rcutiny.h | 3 +-- lib/vsprintf.c | 2 +- 3 files changed, 5 insertions(+), 4 deletions(-) diff --git a/include/linux/preempt.h b/include/linux/preempt.h index 9881eac0698f..9a1c924e2c6c 100644 --- a/include/linux/preempt.h +++ b/include/linux/preempt.h @@ -92,12 +92,14 @@ * in_nmi() - We're in NMI context * in_hardirq() - We're in hard IRQ context * in_serving_softirq() - We're in softirq context + * in_serving_irq() - We're in nmi, hardirq or softirq context * in_task() - We're in task context */ #define in_nmi() (nmi_count()) #define in_hardirq() (hardirq_count()) #define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET) -#define in_task() (!(in_nmi() | in_hardirq() | in_serving_softirq())) +#define in_serving_irq() (in_nmi() | in_hardirq() | in_serving_softirq()) +#define in_task() (!in_serving_irq()) /* * The following macros are deprecated and should not be used in new code: diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index 7fedbd33d5d2..812d42f22e9c 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -87,8 +87,7 @@ static inline void rcu_irq_exit_irqson(void) { } static inline void rcu_irq_enter_irqson(void) { } static inline void rcu_irq_exit(void) { } static inline void rcu_irq_exit_check_preempt(void) { } -#define rcu_is_idle_cpu(cpu) \ - (is_idle_task(current) && !in_nmi() && !in_hardirq() && !in_serving_softirq()) +#define rcu_is_idle_cpu(cpu) (is_idle_task(current) && !in_serving_irq()) static inline void exit_rcu(void) { } static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t) { diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 2c5b4351330c..9324439c8543 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -865,7 +865,7 @@ char *restricted_pointer(char *buf, char *end, const void *ptr, * kptr_restrict==1 cannot be used in IRQ context * because its test for CAP_SYSLOG would be meaningless. */ - if (in_hardirq() || in_serving_softirq() || in_nmi()) { + if (in_serving_irq()) { if (spec.field_width == -1) spec.field_width = 2 * sizeof(ptr); return error_string(buf, end, "pK-error", spec); -- 2.30.2 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] preempt: add in_serving_irq() and apply to rcutiny and vsprintf 2021-08-14 1:42 [PATCH] preempt: add in_serving_irq() and apply to rcutiny and vsprintf Changbin Du @ 2021-08-16 16:03 ` Boqun Feng 2021-08-18 23:59 ` Changbin Du 0 siblings, 1 reply; 5+ messages in thread From: Boqun Feng @ 2021-08-16 16:03 UTC (permalink / raw) To: Changbin Du Cc: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann, Paul E. McKenney, Josh Triplett, Sergey Senozhatsky, linux-kernel, rcu On Sat, Aug 14, 2021 at 09:42:34AM +0800, Changbin Du wrote: > At some places we need to determine whether we're in nmi, hardirq or > softirq context. This adds a macro in_serving_irq() as a shortcut for > that. > > Meanwhile, apply this new macro to existing code in rcutiny and vsprintf. > > Signed-off-by: Changbin Du <changbin.du@gmail.com> > --- > include/linux/preempt.h | 4 +++- > include/linux/rcutiny.h | 3 +-- > lib/vsprintf.c | 2 +- > 3 files changed, 5 insertions(+), 4 deletions(-) > > diff --git a/include/linux/preempt.h b/include/linux/preempt.h > index 9881eac0698f..9a1c924e2c6c 100644 > --- a/include/linux/preempt.h > +++ b/include/linux/preempt.h > @@ -92,12 +92,14 @@ > * in_nmi() - We're in NMI context > * in_hardirq() - We're in hard IRQ context > * in_serving_softirq() - We're in softirq context > + * in_serving_irq() - We're in nmi, hardirq or softirq context > * in_task() - We're in task context > */ > #define in_nmi() (nmi_count()) > #define in_hardirq() (hardirq_count()) > #define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET) > -#define in_task() (!(in_nmi() | in_hardirq() | in_serving_softirq())) > +#define in_serving_irq() (in_nmi() | in_hardirq() | in_serving_softirq()) > +#define in_task() (!in_serving_irq()) > So in_serving_irq() is !in_task(), right? If so, why not... > /* > * The following macros are deprecated and should not be used in new code: > diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h > index 7fedbd33d5d2..812d42f22e9c 100644 > --- a/include/linux/rcutiny.h > +++ b/include/linux/rcutiny.h > @@ -87,8 +87,7 @@ static inline void rcu_irq_exit_irqson(void) { } > static inline void rcu_irq_enter_irqson(void) { } > static inline void rcu_irq_exit(void) { } > static inline void rcu_irq_exit_check_preempt(void) { } > -#define rcu_is_idle_cpu(cpu) \ > - (is_idle_task(current) && !in_nmi() && !in_hardirq() && !in_serving_softirq()) > +#define rcu_is_idle_cpu(cpu) (is_idle_task(current) && !in_serving_irq()) ... use in_task() here, and ... > static inline void exit_rcu(void) { } > static inline bool rcu_preempt_need_deferred_qs(struct task_struct *t) > { > diff --git a/lib/vsprintf.c b/lib/vsprintf.c > index 2c5b4351330c..9324439c8543 100644 > --- a/lib/vsprintf.c > +++ b/lib/vsprintf.c > @@ -865,7 +865,7 @@ char *restricted_pointer(char *buf, char *end, const void *ptr, > * kptr_restrict==1 cannot be used in IRQ context > * because its test for CAP_SYSLOG would be meaningless. > */ > - if (in_hardirq() || in_serving_softirq() || in_nmi()) { > + if (in_serving_irq()) { ... use !in_task() here? And don't introduce the in_serving_irq() at all. Regards, Boqun > if (spec.field_width == -1) > spec.field_width = 2 * sizeof(ptr); > return error_string(buf, end, "pK-error", spec); > -- > 2.30.2 > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] preempt: add in_serving_irq() and apply to rcutiny and vsprintf 2021-08-16 16:03 ` Boqun Feng @ 2021-08-18 23:59 ` Changbin Du 2021-08-19 1:56 ` Boqun Feng 0 siblings, 1 reply; 5+ messages in thread From: Changbin Du @ 2021-08-18 23:59 UTC (permalink / raw) To: Boqun Feng Cc: Changbin Du, Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann, Paul E. McKenney, Josh Triplett, Sergey Senozhatsky, linux-kernel, rcu On Tue, Aug 17, 2021 at 12:03:16AM +0800, Boqun Feng wrote: > On Sat, Aug 14, 2021 at 09:42:34AM +0800, Changbin Du wrote: > > At some places we need to determine whether we're in nmi, hardirq or > > softirq context. This adds a macro in_serving_irq() as a shortcut for > > that. > > > > Meanwhile, apply this new macro to existing code in rcutiny and vsprintf. > > > > Signed-off-by: Changbin Du <changbin.du@gmail.com> > > --- > > include/linux/preempt.h | 4 +++- > > include/linux/rcutiny.h | 3 +-- > > lib/vsprintf.c | 2 +- > > 3 files changed, 5 insertions(+), 4 deletions(-) > > > > diff --git a/include/linux/preempt.h b/include/linux/preempt.h > > index 9881eac0698f..9a1c924e2c6c 100644 > > --- a/include/linux/preempt.h > > +++ b/include/linux/preempt.h > > @@ -92,12 +92,14 @@ > > * in_nmi() - We're in NMI context > > * in_hardirq() - We're in hard IRQ context > > * in_serving_softirq() - We're in softirq context > > + * in_serving_irq() - We're in nmi, hardirq or softirq context > > * in_task() - We're in task context > > */ > > #define in_nmi() (nmi_count()) > > #define in_hardirq() (hardirq_count()) > > #define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET) > > -#define in_task() (!(in_nmi() | in_hardirq() | in_serving_softirq())) > > +#define in_serving_irq() (in_nmi() | in_hardirq() | in_serving_softirq()) > > +#define in_task() (!in_serving_irq()) > > > > So in_serving_irq() is !in_task(), right? If so, why not... > Adding in_serving_irq() is to reflect the real purpose so improve readability. And can we preserve that !in_task() means in serving irq context in future? I don't know. -- Cheers, Changbin Du ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] preempt: add in_serving_irq() and apply to rcutiny and vsprintf 2021-08-18 23:59 ` Changbin Du @ 2021-08-19 1:56 ` Boqun Feng 2021-08-19 23:00 ` Changbin Du 0 siblings, 1 reply; 5+ messages in thread From: Boqun Feng @ 2021-08-19 1:56 UTC (permalink / raw) To: Changbin Du Cc: Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann, Paul E. McKenney, Josh Triplett, Sergey Senozhatsky, linux-kernel, rcu, Thomas Gleixner, Frederic Weisbecker [Cc Thomas and Frederic since they contributed the clean-up to these macros recently] Background for discussion: https://lore.kernel.org/lkml/20210814014234.51395-1-changbin.du@gmail.com/ On Thu, Aug 19, 2021 at 07:59:16AM +0800, Changbin Du wrote: > On Tue, Aug 17, 2021 at 12:03:16AM +0800, Boqun Feng wrote: > > On Sat, Aug 14, 2021 at 09:42:34AM +0800, Changbin Du wrote: > > > At some places we need to determine whether we're in nmi, hardirq or > > > softirq context. This adds a macro in_serving_irq() as a shortcut for > > > that. > > > > > > Meanwhile, apply this new macro to existing code in rcutiny and vsprintf. > > > > > > Signed-off-by: Changbin Du <changbin.du@gmail.com> > > > --- > > > include/linux/preempt.h | 4 +++- > > > include/linux/rcutiny.h | 3 +-- > > > lib/vsprintf.c | 2 +- > > > 3 files changed, 5 insertions(+), 4 deletions(-) > > > > > > diff --git a/include/linux/preempt.h b/include/linux/preempt.h > > > index 9881eac0698f..9a1c924e2c6c 100644 > > > --- a/include/linux/preempt.h > > > +++ b/include/linux/preempt.h > > > @@ -92,12 +92,14 @@ > > > * in_nmi() - We're in NMI context > > > * in_hardirq() - We're in hard IRQ context > > > * in_serving_softirq() - We're in softirq context > > > + * in_serving_irq() - We're in nmi, hardirq or softirq context > > > * in_task() - We're in task context > > > */ > > > #define in_nmi() (nmi_count()) > > > #define in_hardirq() (hardirq_count()) > > > #define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET) > > > -#define in_task() (!(in_nmi() | in_hardirq() | in_serving_softirq())) > > > +#define in_serving_irq() (in_nmi() | in_hardirq() | in_serving_softirq()) > > > +#define in_task() (!in_serving_irq()) > > > > > > > So in_serving_irq() is !in_task(), right? If so, why not... > > > Adding in_serving_irq() is to reflect the real purpose so improve readability. > And can we preserve that !in_task() means in serving irq context in future? I don't know. > Sure, no one could predict the future. But if a third context (other than thread context and {hard,soft}irq context) comes up, which I think is highly unlikely, we could (and should) audit all callsites of in_task() for necessary adjustment. And introducing in_serving_irq() won't help us in that case, because we will still need to audit usage of in_serving_irq(), for example, let's say rcu_is_idle_cpu() for RCU_TINY is defined as #define rcu_is_idle_cpu(cpu) (is_idle_task(current) && !in_serving_irq()) and we have a new type of context, and we can use in_other() to test whether we are in it. Now even with in_serving_irq() introduced, we still need to make sure the correct version of rcu_is_idle_cpu() is either (is_idle_task(current) && (!in_serving_irq() && !in_other())) or (is_idle_task(current) && !in_serving_irq()) Therefore, I don't see the point of introducing in_serving_irq(). Regards, Boqun > -- > Cheers, > Changbin Du ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] preempt: add in_serving_irq() and apply to rcutiny and vsprintf 2021-08-19 1:56 ` Boqun Feng @ 2021-08-19 23:00 ` Changbin Du 0 siblings, 0 replies; 5+ messages in thread From: Changbin Du @ 2021-08-19 23:00 UTC (permalink / raw) To: Boqun Feng Cc: Changbin Du, Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Dietmar Eggemann, Paul E. McKenney, Josh Triplett, Sergey Senozhatsky, linux-kernel, rcu, Thomas Gleixner, Frederic Weisbecker On Thu, Aug 19, 2021 at 09:56:45AM +0800, Boqun Feng wrote: > [Cc Thomas and Frederic since they contributed the clean-up to these > macros recently] > > Background for discussion: > > https://lore.kernel.org/lkml/20210814014234.51395-1-changbin.du@gmail.com/ > > On Thu, Aug 19, 2021 at 07:59:16AM +0800, Changbin Du wrote: > > On Tue, Aug 17, 2021 at 12:03:16AM +0800, Boqun Feng wrote: > > > On Sat, Aug 14, 2021 at 09:42:34AM +0800, Changbin Du wrote: > > > > At some places we need to determine whether we're in nmi, hardirq or > > > > softirq context. This adds a macro in_serving_irq() as a shortcut for > > > > that. > > > > > > > > Meanwhile, apply this new macro to existing code in rcutiny and vsprintf. > > > > > > > > Signed-off-by: Changbin Du <changbin.du@gmail.com> > > > > --- > > > > include/linux/preempt.h | 4 +++- > > > > include/linux/rcutiny.h | 3 +-- > > > > lib/vsprintf.c | 2 +- > > > > 3 files changed, 5 insertions(+), 4 deletions(-) > > > > > > > > diff --git a/include/linux/preempt.h b/include/linux/preempt.h > > > > index 9881eac0698f..9a1c924e2c6c 100644 > > > > --- a/include/linux/preempt.h > > > > +++ b/include/linux/preempt.h > > > > @@ -92,12 +92,14 @@ > > > > * in_nmi() - We're in NMI context > > > > * in_hardirq() - We're in hard IRQ context > > > > * in_serving_softirq() - We're in softirq context > > > > + * in_serving_irq() - We're in nmi, hardirq or softirq context > > > > * in_task() - We're in task context > > > > */ > > > > #define in_nmi() (nmi_count()) > > > > #define in_hardirq() (hardirq_count()) > > > > #define in_serving_softirq() (softirq_count() & SOFTIRQ_OFFSET) > > > > -#define in_task() (!(in_nmi() | in_hardirq() | in_serving_softirq())) > > > > +#define in_serving_irq() (in_nmi() | in_hardirq() | in_serving_softirq()) > > > > +#define in_task() (!in_serving_irq()) > > > > > > > > > > So in_serving_irq() is !in_task(), right? If so, why not... > > > > > Adding in_serving_irq() is to reflect the real purpose so improve readability. > > And can we preserve that !in_task() means in serving irq context in future? I don't know. > > > > Sure, no one could predict the future. But if a third context (other > than thread context and {hard,soft}irq context) comes up, which I think > is highly unlikely, we could (and should) audit all callsites of > in_task() for necessary adjustment. And introducing in_serving_irq() > won't help us in that case, because we will still need to audit usage of > in_serving_irq(), for example, let's say rcu_is_idle_cpu() for RCU_TINY > is defined as > > #define rcu_is_idle_cpu(cpu) (is_idle_task(current) && !in_serving_irq()) > > and we have a new type of context, and we can use in_other() to test > whether we are in it. Now even with in_serving_irq() introduced, we > still need to make sure the correct version of rcu_is_idle_cpu() is > either > > (is_idle_task(current) && (!in_serving_irq() && !in_other())) > > or > > (is_idle_task(current) && !in_serving_irq()) > > Therefore, I don't see the point of introducing in_serving_irq(). > ok, as in_serving_irq() is only used in two places, it is not common to judge if it is in serving irq context. So this new macro doesn't help much. > Regards, > Boqun > > > -- > > Cheers, > > Changbin Du -- Cheers, Changbin Du ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2021-08-19 23:00 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-08-14 1:42 [PATCH] preempt: add in_serving_irq() and apply to rcutiny and vsprintf Changbin Du 2021-08-16 16:03 ` Boqun Feng 2021-08-18 23:59 ` Changbin Du 2021-08-19 1:56 ` Boqun Feng 2021-08-19 23:00 ` Changbin Du
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