From: Ben Hutchings ben@decadent.org.uk
From: Peter Zijlstra peterz@infradead.org
commit 499f5aca2cdd5e958b27e2655e7e7f82524f46b1 upstream.
futex_top_waiter() returns the top-waiter on the pi_mutex. Assinging this to a variable 'match' totally obscures the code.
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/20170322104151.554710645@infradead.org Signed-off-by: Thomas Gleixner tglx@linutronix.de [bwh: Backported to 4.9: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/futex.c | 28 ++++++++++++++-------------- 1 file changed, 14 insertions(+), 14 deletions(-)
--- a/kernel/futex.c +++ b/kernel/futex.c @@ -1352,14 +1352,14 @@ static int lookup_pi_state(u32 __user *u union futex_key *key, struct futex_pi_state **ps, struct task_struct **exiting) { - struct futex_q *match = futex_top_waiter(hb, key); + struct futex_q *top_waiter = futex_top_waiter(hb, key);
/* * If there is a waiter on that futex, validate it and * attach to the pi_state when the validation succeeds. */ - if (match) - return attach_to_pi_state(uaddr, uval, match->pi_state, ps); + if (top_waiter) + return attach_to_pi_state(uaddr, uval, top_waiter->pi_state, ps);
/* * We are the first waiter - try to look up the owner based on @@ -1414,7 +1414,7 @@ static int futex_lock_pi_atomic(u32 __us int set_waiters) { u32 uval, newval, vpid = task_pid_vnr(task); - struct futex_q *match; + struct futex_q *top_waiter; int ret;
/* @@ -1440,9 +1440,9 @@ static int futex_lock_pi_atomic(u32 __us * Lookup existing state first. If it exists, try to attach to * its pi_state. */ - match = futex_top_waiter(hb, key); - if (match) - return attach_to_pi_state(uaddr, uval, match->pi_state, ps); + top_waiter = futex_top_waiter(hb, key); + if (top_waiter) + return attach_to_pi_state(uaddr, uval, top_waiter->pi_state, ps);
/* * No waiter and user TID is 0. We are here because the @@ -1532,11 +1532,11 @@ static void mark_wake_futex(struct wake_ q->lock_ptr = NULL; }
-static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this, +static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *top_waiter, struct futex_hash_bucket *hb) { struct task_struct *new_owner; - struct futex_pi_state *pi_state = this->pi_state; + struct futex_pi_state *pi_state = top_waiter->pi_state; u32 uninitialized_var(curval), newval; WAKE_Q(wake_q); bool deboost; @@ -1557,7 +1557,7 @@ static int wake_futex_pi(u32 __user *uad
/* * When we interleave with futex_lock_pi() where it does - * rt_mutex_timed_futex_lock(), we might observe @this futex_q waiter, + * rt_mutex_timed_futex_lock(), we might observe @top_waiter futex_q waiter, * but the rt_mutex's wait_list can be empty (either still, or again, * depending on which side we land). * @@ -2975,7 +2975,7 @@ static int futex_unlock_pi(u32 __user *u u32 uninitialized_var(curval), uval, vpid = task_pid_vnr(current); union futex_key key = FUTEX_KEY_INIT; struct futex_hash_bucket *hb; - struct futex_q *match; + struct futex_q *top_waiter; int ret;
retry: @@ -2999,9 +2999,9 @@ retry: * all and we at least want to know if user space fiddled * with the futex value instead of blindly unlocking. */ - match = futex_top_waiter(hb, &key); - if (match) { - ret = wake_futex_pi(uaddr, uval, match, hb); + top_waiter = futex_top_waiter(hb, &key); + if (top_waiter) { + ret = wake_futex_pi(uaddr, uval, top_waiter, hb); /* * In case of success wake_futex_pi dropped the hash * bucket lock.