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authorDavide Libenzi <davidel@xmailserver.org>2008-10-17 16:17:40 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-26 12:09:49 -0700
commit9ce209d64d820a6d5ed6b952e2c0f917faad6031 (patch)
tree817c5bd01e6666c8269d29d3d8292b5e75ea7fb3 /drivers/char
parent4d36a9e65d4966b433b2f3424d9457468bc80e00 (diff)
epoll: avoid double-inserts in case of EFAULT
In commit f337b9c58332bdecde965b436e47ea4c94d30da0 ("epoll: drop unnecessary test") Thomas found that there is an unnecessary (always true) test in ep_send_events(). The callback never inserts into ->rdllink while the send loop is performed, and also does the ~EP_PRIVATE_BITS test. Given we're holding the mutex during this time, the conditions tested inside the loop are always true. HOWEVER. The test "!ep_is_linked(&epi->rdllink)" wasn't there because we insert into ->rdllink, but because the send-events loop might terminate before the whole list is scanned (-EFAULT). In such cases, when the loop terminates early, and when a (leftover) file received an event while we're performing the lockless loop, we need such test to avoid to double insert the epoll items. The list_splice() done a few steps below, will correctly re-insert the ones that were left on "txlist". This should fix the kenrel.org bugzilla entry 11831. Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char')
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