https://github.com/torvalds/linux
Revision 474328c06e3ee75bb6b92826fec90fdc8ef3c573 authored by Roman Penyaev on 08 May 2020, 01:36:13 UTC, committed by Linus Torvalds on 08 May 2020, 02:27:21 UTC
This test case catches lost wake up introduced by commit 339ddb53d373 ("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 <rpenyaev@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Khazhismel Kumykov <khazhy@google.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Heiher <r@hev.cc> Cc: Jason Baron <jbaron@akamai.com> Link: http://lkml.kernel.org/r/20200430130326.1368509-1-rpenyaev@suse.de Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Tip revision: 474328c06e3ee75bb6b92826fec90fdc8ef3c573 authored by Roman Penyaev on 08 May 2020, 01:36:13 UTC
kselftests: introduce new epoll60 testcase for catching lost wakeups
kselftests: introduce new epoll60 testcase for catching lost wakeups
Tip revision: 474328c
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