From: Thomas Gleixner Date: Wed, 28 Oct 2009 19:26:48 +0000 (+0100) Subject: futex: Fix spurious wakeup for requeue_pi really X-Git-Tag: v2.6.32-rc6~15^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=11df6dddcbc38affb7473aad3d962baf8414a947;p=pandora-kernel.git futex: Fix spurious wakeup for requeue_pi really The requeue_pi path doesn't use unqueue_me() (and the racy lock_ptr == NULL test) nor does it use the wake_list of futex_wake() which where the reason for commit 41890f2 (futex: Handle spurious wake up) See debugging discussing on LKML Message-ID: <4AD4080C.20703@us.ibm.com> The changes in this fix to the wait_requeue_pi path were considered to be a likely unecessary, but harmless safety net. But it turns out that due to the fact that for unknown $@#!*( reasons EWOULDBLOCK is defined as EAGAIN we built an endless loop in the code path which returns correctly EWOULDBLOCK. Spurious wakeups in wait_requeue_pi code path are unlikely so we do the easy solution and return EWOULDBLOCK^WEAGAIN to user space and let it deal with the spurious wakeup. Cc: Darren Hart Cc: Peter Zijlstra Cc: Eric Dumazet Cc: John Stultz Cc: Dinakar Guniguntala LKML-Reference: <4AE23C74.1090502@us.ibm.com> Cc: stable@kernel.org Signed-off-by: Thomas Gleixner --- Reading git-diff-tree failed