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

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Message-Id: <20210814014234.51395-1-changbin.du@gmail.com>
Date:   Sat, 14 Aug 2021 09:42:34 +0800
From:   Changbin Du <changbin.du@...il.com>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@...hat.com>
Cc:     Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Josh Triplett <josh@...htriplett.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        linux-kernel@...r.kernel.org, rcu@...r.kernel.org,
        Changbin Du <changbin.du@...il.com>
Subject: [PATCH] preempt: add in_serving_irq() and apply to rcutiny and vsprintf

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@...il.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