From: Takashi Iwai Date: Mon, 4 Jul 2016 12:02:15 +0000 (+0200) Subject: ALSA: timer: Fix negative queue usage by racy accesses X-Git-Tag: v3.2.82~14 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6530d0788e7048a1f9879d476122c916c6f72a96;p=pandora-kernel.git ALSA: timer: Fix negative queue usage by racy accesses commit 3fa6993fef634e05d200d141a85df0b044572364 upstream. The user timer tu->qused counter may go to a negative value when multiple concurrent reads are performed since both the check and the decrement of tu->qused are done in two individual locked contexts. This results in bogus read outs, and the endless loop in the user-space side. The fix is to move the decrement of the tu->qused counter into the same spinlock context as the zero-check of the counter. Signed-off-by: Takashi Iwai Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed