From: Peter Zijlstra peterz@infradead.org
commit 499f5aca2cdd5e958b27e2655e7e7f82524f46b1 uptream.
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 Tested-by: Henrik Austad haustad@cisco.com --- kernel/futex.c | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c index a26d217..bb87324 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1116,14 +1116,14 @@ static int attach_to_pi_owner(u32 uval, union futex_key *key, static int lookup_pi_state(u32 uval, struct futex_hash_bucket *hb, union futex_key *key, struct futex_pi_state **ps) { - 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(uval, match->pi_state, ps); + if (top_waiter) + return attach_to_pi_state(uval, top_waiter->pi_state, ps);
/* * We are the first waiter - try to look up the owner based on @@ -1170,7 +1170,7 @@ static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb, struct task_struct *task, int set_waiters) { u32 uval, newval, vpid = task_pid_vnr(task); - struct futex_q *match; + struct futex_q *top_waiter; int ret;
/* @@ -1196,9 +1196,9 @@ static int futex_lock_pi_atomic(u32 __user *uaddr, struct futex_hash_bucket *hb, * 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(uval, match->pi_state, ps); + top_waiter = futex_top_waiter(hb, key); + if (top_waiter) + return attach_to_pi_state(uval, top_waiter->pi_state, ps);
/* * No waiter and user TID is 0. We are here because the @@ -1288,11 +1288,11 @@ static void mark_wake_futex(struct wake_q_head *wake_q, struct futex_q *q) 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; @@ -1313,11 +1313,11 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *this,
/* * It is possible that the next waiter (the one that brought - * this owner to the kernel) timed out and is no longer + * top_waiter owner to the kernel) timed out and is no longer * waiting on the lock. */ if (!new_owner) - new_owner = this->task; + new_owner = top_waiter->task;
/* * We pass it to the next owner. The WAITERS bit is always @@ -2639,7 +2639,7 @@ static int futex_unlock_pi(u32 __user *uaddr, unsigned int flags) 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: @@ -2663,9 +2663,9 @@ 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.