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author | Manfred Spraul <manfred@colorfullife.com> | 2013-09-30 13:45:06 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-30 14:31:01 -0700 |
commit | 6d07b68ce16ae9535955ba2059dedba5309c3ca1 (patch) | |
tree | f8eccb1e9ff34ffb41225d247329d7e73148b6fe /init | |
parent | 5e9d527591421ccdb16acb8c23662231135d8686 (diff) | |
download | op-kernel-dev-6d07b68ce16ae9535955ba2059dedba5309c3ca1.zip op-kernel-dev-6d07b68ce16ae9535955ba2059dedba5309c3ca1.tar.gz |
ipc/sem.c: optimize sem_lock()
Operations that need access to the whole array must guarantee that there
are no simple operations ongoing. Right now this is achieved by
spin_unlock_wait(sem->lock) on all semaphores.
If complex_count is nonzero, then this spin_unlock_wait() is not
necessary, because it was already performed in the past by the thread
that increased complex_count and even though sem_perm.lock was dropped
inbetween, no simple operation could have started, because simple
operations cannot start when complex_count is non-zero.
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Mike Galbraith <bitbucket@online.de>
Cc: Rik van Riel <riel@redhat.com>
Reviewed-by: Davidlohr Bueso <davidlohr@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'init')
0 files changed, 0 insertions, 0 deletions