linux-kernel - [PATCH 2/3] futex: Add missing annotation for wake_futex

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Message-Id: <a3868cdf0328e5953d6c12fe1e94fb2d8932044b.1579893447.git.jbi.octave@gmail.com>
Date:   Fri, 24 Jan 2020 20:12:19 +0000
From:   Jules Irenge <jbi.octave@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     boqun.feng@...il.com, Jules Irenge <jbi.octave@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Darren Hart <dvhart@...radead.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] futex: Add missing annotation for wake_futex_pi()

Sparse reports a warning at wake_futex_pi()

|warning: context imbalance in wake_futex_pi() - unexpected unlock
To fix this,
a __releases(&pi_state->pi_mutex.wait_lock) annotation is added
Given that wake_futex_pi() does actually call
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock)
This not only fixes the warning
but also improves on the readability of the code.

Signed-off-by: Jules Irenge <jbi.octave@...il.com>
---
 kernel/futex.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/futex.c b/kernel/futex.c
index 03c518e9747e..8bc288a7187f 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1549,6 +1549,7 @@ static void mark_wake_futex(struct wake_q_head *wake_q, struct futex_q *q)
  * Caller must hold a reference on @pi_state.
  */
 static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_state)
+	__releases(&pi_state->pi_mutex.wait_lock)
 {
 	u32 uninitialized_var(curval), newval;
 	struct task_struct *new_owner;
-- 
2.24.1