futex: Don't enable IRQs unconditionally in put_pi_state()

The exit_pi_state_list() function calls put_pi_state() with IRQs disabled
and is not expecting that IRQs will be enabled inside the function.

Use the _irqsave() variant so that IRQs are restored to the original state
instead of being enabled unconditionally.

Fixes: 153fbd1226fb ("futex: Fix more put_pi_state() vs. exit_pi_state_list() races")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201106085205.GA1159983@mwanda

diff --git a/kernel/futex.c b/kernel/futex.c
index ac328874f6e583c29c652f2980202f56877cfa60..00259c7e288eea4fba549e535be2e96b623bbfc6 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -788,8 +788,9 @@ static void put_pi_state(struct futex_pi_state *pi_state)
         */
        if (pi_state->owner) {
                struct task_struct *owner;
+               unsigned long flags;
 
-               raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
+               raw_spin_lock_irqsave(&pi_state->pi_mutex.wait_lock, flags);
                owner = pi_state->owner;
                if (owner) {
                        raw_spin_lock(&owner->pi_lock);
@@ -797,7 +798,7 @@ static void put_pi_state(struct futex_pi_state *pi_state)
                        raw_spin_unlock(&owner->pi_lock);
                }
                rt_mutex_proxy_unlock(&pi_state->pi_mutex, owner);
-               raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
+               raw_spin_unlock_irqrestore(&pi_state->pi_mutex.wait_lock, flags);
        }
 
        if (current->pi_state_cache) {