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author | Ben Hutchings <ben@decadent.org.uk> | 2021-03-01 18:31:22 +0100 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-03-07 11:25:54 +0100 |
commit | 921a7e30b1c26e2ae654d1908f55e3720f2c7f7c (patch) | |
tree | fc59ebde7c495ec37fc5d89a6c2f4e6751a14907 /kernel | |
parent | bfefc9e38d18167a93e670579ce662f2bcb40fe4 (diff) | |
download | linux-stable-921a7e30b1c26e2ae654d1908f55e3720f2c7f7c.tar.gz linux-stable-921a7e30b1c26e2ae654d1908f55e3720f2c7f7c.tar.bz2 linux-stable-921a7e30b1c26e2ae654d1908f55e3720f2c7f7c.zip |
futex: Cleanup refcounting
From: Peter Zijlstra <peterz@infradead.org>
commit bf92cf3a5100f5a0d5f9834787b130159397cb22 upstream.
Add a put_pit_state() as counterpart for get_pi_state() so the refcounting
becomes consistent.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: juri.lelli@arm.com
Cc: bigeasy@linutronix.de
Cc: xlpang@redhat.com
Cc: rostedt@goodmis.org
Cc: mathieu.desnoyers@efficios.com
Cc: jdesfossez@efficios.com
Cc: dvhart@infradead.org
Cc: bristot@redhat.com
Link: http://lkml.kernel.org/r/20170322104151.801778516@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
-rw-r--r-- | kernel/futex.c | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/kernel/futex.c b/kernel/futex.c index 1cb5064548d6..bf410a4fab71 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -827,7 +827,7 @@ static int refill_pi_state_cache(void) return 0; } -static struct futex_pi_state * alloc_pi_state(void) +static struct futex_pi_state *alloc_pi_state(void) { struct futex_pi_state *pi_state = current->pi_state_cache; @@ -860,6 +860,11 @@ static void pi_state_update_owner(struct futex_pi_state *pi_state, } } +static void get_pi_state(struct futex_pi_state *pi_state) +{ + WARN_ON_ONCE(!atomic_inc_not_zero(&pi_state->refcount)); +} + /* * Drops a reference to the pi_state object and frees or caches it * when the last reference is gone. @@ -901,7 +906,7 @@ static void put_pi_state(struct futex_pi_state *pi_state) * Look up the task based on what TID userspace gave us. * We dont trust it. */ -static struct task_struct * futex_find_get_task(pid_t pid) +static struct task_struct *futex_find_get_task(pid_t pid) { struct task_struct *p; @@ -1149,7 +1154,7 @@ static int attach_to_pi_state(u32 __user *uaddr, u32 uval, goto out_einval; out_attach: - atomic_inc(&pi_state->refcount); + get_pi_state(pi_state); raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); *ps = pi_state; return 0; @@ -2210,7 +2215,7 @@ retry_private: * refcount on the pi_state and store the pointer in * the futex_q object of the waiter. */ - atomic_inc(&pi_state->refcount); + get_pi_state(pi_state); this->pi_state = pi_state; ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex, this->rt_waiter, |