[PATCH] preempt: add in_serving_irq() and apply to rcutiny and vsprintf

From: Changbin Du
Date: Fri Aug 13 2021 - 21:43:45 EST


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())

/*
* 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