On Wed, Mar 22, 2017 at 11:35:48AM +0100, Peter Zijlstra wrote: > 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) <[email protected]>
Yup, still happy to see this one. Reviewed-by: Darren Hart (VMware) <[email protected]> > --- > kernel/futex.c | 30 +++++++++++++++--------------- > 1 file changed, 15 insertions(+), 15 deletions(-) > > --- a/kernel/futex.c > +++ b/kernel/futex.c > @@ -1120,14 +1120,14 @@ static int attach_to_pi_owner(u32 uval, > 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 > @@ -1174,7 +1174,7 @@ static int futex_lock_pi_atomic(u32 __us > 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; > > /* > @@ -1200,9 +1200,9 @@ 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(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 > @@ -1292,11 +1292,11 @@ 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; > DEFINE_WAKE_Q(wake_q); > bool deboost; > @@ -1317,11 +1317,11 @@ static int wake_futex_pi(u32 __user *uad > > /* > * 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 > @@ -2631,7 +2631,7 @@ 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: > @@ -2655,9 +2655,9 @@ static int futex_unlock_pi(u32 __user *u > * 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. > > > -- Darren Hart VMware Open Source Technology Center
