linux-kernel - [PATCH v2 1/2] hrtimer: Add missing annotation to lock_hrtimer

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Message-Id: <20200127023008.87124-1-jbi.octave@gmail.com>
Date:   Mon, 27 Jan 2020 02:30:08 +0000
From:   Jules Irenge <jbi.octave@...il.com>
To:     boqun.feng@...il.com
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        Jules Irenge <jbi.octave@...il.com>
Subject: [PATCH v2 1/2] hrtimer: Add missing annotation to lock_hrtimer_base()

Sparse reports several warnings;

warning: context imbalance in lock_hrtimer_base() - wrong count at exit
warning: context imbalance in hrtimer_start_range_ns() - unexpected unlock
warning: context imbalance in hrtimer_try_to_cancel() - unexpected unlock
warning: context imbalance in __hrtimer_get_remaining() - unexpected unlock

The root cause is a missing annotation of lock_hrtimer_base()
which also causes the "unexpected unlock" warnings.
To fix these,
an __acquires(timer) annotation is added to lock_hrtimer_base().
Given that lock_hrtimer_base() does actually call READ_ONCE(timer->base),
this fixes the warnings.

Signed-off-by: Jules Irenge <jbi.octave@...il.com>
---
 kernel/time/hrtimer.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 8de90ea31280..d149b599bdf7 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -157,9 +157,9 @@ static inline bool is_migration_base(struct hrtimer_clock_base *base)
  * possible to set timer->base = &migration_base and drop the lock: the timer
  * remains locked.
  */
-static
-struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
-					     unsigned long *flags)
+static struct hrtimer_clock_base *
+lock_hrtimer_base(const struct hrtimer *timer,
+		  unsigned long *flags) __acquires(timer)
 {
 	struct hrtimer_clock_base *base;
 
-- 
2.24.1