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author | Thomas Gleixner <tglx@linutronix.de> | 2009-05-05 19:21:40 +0200 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2009-05-15 15:24:18 +0200 |
commit | f1a11e0576c7a73d759d05d776692b2b2d37172b (patch) | |
tree | 3cb845c4cfd48cdbe0755d057c2698657fb965b5 /Documentation/video-output.txt | |
parent | b30505c81a9d4adea8b70ecff512b0216929b797 (diff) |
futex: remove the wait queue
The waitqueue which is used in struct futex_q is a leftover from the
futexfd implementation. There is no need to use a waitqueue at all, as
the waiting task is the only user of it. The waitqueue just adds
additional locking and a loop in the wake up path which both can be
avoided.
We have already a task reference in struct futex_q which is used for
PI futexes. Use it for normal futexes as well and just wake up the
task directly.
The logic of signalling the futex wakeup via setting q->lock_ptr to
NULL is kept with the difference that we set it NULL before doing the
wakeup. This opens an exit race window vs. a non futex wake up of the
to be woken up task, which we prevent with get_task_struct /
put_task_struct on the waiter.
[ Impact: simplification ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'Documentation/video-output.txt')
0 files changed, 0 insertions, 0 deletions