From d8d88fbb186fe3ea37b2a58adb32413c98b59656 Mon Sep 17 00:00:00 2001 From: Darren Hart Date: Mon, 21 Sep 2009 22:30:30 -0700 Subject: futex: Correct futex_q woken state commentary Use kernel-doc format to describe struct futex_q. Correct the wakeup definition to eliminate the statement about waking the waiter between the plist_del() and the q->lock_ptr = 0. Note in the comment that PI futexes have a different definition of the woken state. Signed-off-by: Darren Hart Acked-by: Peter Zijlstra Cc: Steven Rostedt Cc: Eric Dumazet Cc: Dinakar Guniguntala Cc: John Stultz LKML-Reference: <20090922053029.8717.62798.stgit@Aeon> Signed-off-by: Ingo Molnar --- kernel/futex.c | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-) (limited to 'kernel/futex.c') diff --git a/kernel/futex.c b/kernel/futex.c index 720fa3dd629d..f92afbe3d3a1 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -89,36 +89,36 @@ struct futex_pi_state { union futex_key key; }; -/* - * We use this hashed waitqueue instead of a normal wait_queue_t, so +/** + * struct futex_q - The hashed futex queue entry, one per waiting task + * @task: the task waiting on the futex + * @lock_ptr: the hash bucket lock + * @key: the key the futex is hashed on + * @pi_state: optional priority inheritance state + * @rt_waiter: rt_waiter storage for use with requeue_pi + * @requeue_pi_key: the requeue_pi target futex key + * @bitset: bitset for the optional bitmasked wakeup + * + * We use this hashed waitqueue, instead of a normal wait_queue_t, so * we can wake only the relevant ones (hashed queues may be shared). * * A futex_q has a woken state, just like tasks have TASK_RUNNING. * It is considered woken when plist_node_empty(&q->list) || q->lock_ptr == 0. * The order of wakup is always to make the first condition true, then - * wake up q->waiter, then make the second condition true. + * the second. + * + * PI futexes are typically woken before they are removed from the hash list via + * the rt_mutex code. See unqueue_me_pi(). */ struct futex_q { struct plist_node list; - /* Waiter reference */ - struct task_struct *task; - /* Which hash list lock to use: */ + struct task_struct *task; spinlock_t *lock_ptr; - - /* Key which the futex is hashed on: */ union futex_key key; - - /* Optional priority inheritance state: */ struct futex_pi_state *pi_state; - - /* rt_waiter storage for requeue_pi: */ struct rt_mutex_waiter *rt_waiter; - - /* The expected requeue pi target futex key: */ union futex_key *requeue_pi_key; - - /* Bitset for the optional bitmasked wakeup */ u32 bitset; }; -- cgit v1.2.3