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Roman Penyaev
474328c06e
This test case catches lost wake up introduced by commit 339ddb53d3
("fs/epoll: remove unnecessary wakeups of nested epoll")
The test is simple: we have 10 threads and 10 event fds. Each thread
can harvest only 1 event. 1 producer fires all 10 events at once and
waits that all 10 events will be observed by 10 threads.
In case of lost wakeup epoll_wait() will timeout and 0 will be returned.
Test case catches two sort of problems: forgotten wakeup on event, which
hits the ->ovflist list, this problem was fixed by:
5a2513239750 ("eventpoll: fix missing wakeup for ovflist in ep_poll_callback")
the other problem is when several sequential events hit the same waiting
thread, thus other waiters get no wakeups. Problem is fixed in the
following patch.
Signed-off-by: Roman Penyaev <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Cc: Khazhismel Kumykov <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Heiher <[email protected]>
Cc: Jason Baron <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>