linux-kernel - [PATCH v2 2/2] futex: Add missing annotation to wake_futex

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Message-Id: <20200127023052.87188-1-jbi.octave@gmail.com>
Date:   Mon, 27 Jan 2020 02:30:51 +0000
From:   Jules Irenge <jbi.octave@...il.com>
To:     boqun.feng@...il.com
Cc:     linux-kernel@...r.kernel.org, tglx@...utronix.de,
        dvhart@...radead.org, peterz@...radead.org, mingo@...hat.com,
        Jules Irenge <jbi.octave@...il.com>
Subject: [PATCH v2 2/2] futex: Add missing annotation to wake_futex_pi()

Sparse reprts warnings;

warning: context imbalance in wake_futex_pi() - unexpected unlock
warning: context imbalance in futex_unlock_p() - different lock contexts
         for basic block

The root cause is a missing annotation at wake_futex_pi()
which also causes the "different lock contexts for basic block" warning.
To fix these,
a __releases(&pi_state) annotation is added to wake_futex_pi().
Given that wake_futex_pi() does actually call
raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock) at exit,
this fixes the warnings

Signed-off-by: Jules Irenge <jbi.octave@...il.com>
---
 kernel/futex.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 0cf84c8664f2..dfcb90b47ed6 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1549,7 +1549,8 @@ 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)
+static int wake_futex_pi(u32 __user *uaddr, u32 uval,
+			 struct futex_pi_state *pi_state) __releases(&pi_state)
 {
 	u32 uninitialized_var(curval), newval;
 	struct task_struct *new_owner;
-- 
2.24.1