From: Linus Torvalds Date: Sat, 4 Nov 2006 21:03:00 +0000 (-0800) Subject: Make sure "user->sigpending" count is in sync X-Git-Tag: v2.6.19-rc5~21 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=10b1fbdb0a0ca91847a534ad26d0bc250c25b74f;p=pandora-kernel.git Make sure "user->sigpending" count is in sync The previous commit (45c18b0bb579b5c1b89f8c99f1b6ffa4c586ba08, aka "Fix unlikely (but possible) race condition on task->user access") fixed a potential oops due to __sigqueue_alloc() getting its "user" pointer out of sync with switch_user(), and accessing a user pointer that had been de-allocated on another CPU. It still left another (much less serious) problem, where a concurrent __sigqueue_alloc and swich_user could cause sigqueue_alloc to do signal pending reference counting for a _different_ user than the one it then actually ended up using. No oops, but we'd end up with the wrong signal accounting. Another case of Oleg's eagle-eyes picking up the problem. This is trivially fixed by just making sure we load whichever "user" structure we decide to use (it doesn't matter _which_ one we pick, we just need to pick one) just once. Acked-by: Oleg Nesterov Cc: Andrew Morton Cc: Ingo Molnar Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed