From: Jeff Layton Date: Fri, 3 Apr 2015 13:04:04 +0000 (-0400) Subject: locks: use cmpxchg to assign i_flctx pointer X-Git-Tag: omap-for-v4.2/o2_dc~121^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0429c2b5c1c4c8ba6cd563c1964baf3ed238df26;p=pandora-kernel.git locks: use cmpxchg to assign i_flctx pointer During the v3.20/v4.0 cycle, I had originally had the code manage the inode->i_flctx pointer using a compare-and-swap operation instead of the i_lock. Sasha Levin though hit a problem while testing with trinity that made me believe that that wasn't safe. At the time, changing the code to protect the i_flctx pointer seemed to fix the issue, but I now think that was just coincidence. The issue was likely the same race that Kirill Shutemov hit while testing the pre-rc1 v4.0 kernel and that Linus spotted. Due to the way that the spinlock was dropped in the middle of flock_lock_file, you could end up with multiple flock locks for the same struct file on the inode. Reinstate the use of a CAS operation to assign this pointer since it's likely to be more efficient and gets the i_lock completely out of the file locking business. Signed-off-by: Jeff Layton --- Reading git-diff-tree failed