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 <[email protected]>
---
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
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 <[email protected]>
> ---
> 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
>
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 <[email protected]>
> > ---
> > 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
[Cc Thomas and Frederic since they contributed the clean-up to these
macros recently]
Background for discussion:
https://lore.kernel.org/lkml/[email protected]/
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 <[email protected]>
> > > ---
> > > 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
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/[email protected]/
>
> 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 <[email protected]>
> > > > ---
> > > > 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