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@xxxxxxxxx>
> ---
> 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
>
