From: Ricardo Cerqueira Date: Thu, 14 Feb 2008 01:41:15 +0000 (-0300) Subject: V4L/DVB (7201): cx88-mpeg: Fix race condition in variable access X-Git-Tag: v2.6.25-rc3~132^2~2 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=baff6cdd3328e7b35c4e155d79105621812bceec;p=linux-2.6-omap-h63xx.git V4L/DVB (7201): cx88-mpeg: Fix race condition in variable access There was a possible race condition in the increment/decrement of the active device references counter. Thanks to Trent Piepho (xyzzy@speakeasy.org) for bringing it up. Signed-off-by: Ricardo Cerqueira Signed-off-by: Mauro Carvalho Chehab --- diff --git a/drivers/media/video/cx88/cx88-mpeg.c b/drivers/media/video/cx88/cx88-mpeg.c index f12733d6bf7..e357f415db0 100644 --- a/drivers/media/video/cx88/cx88-mpeg.c +++ b/drivers/media/video/cx88/cx88-mpeg.c @@ -615,8 +615,8 @@ static int cx8802_request_acquire(struct cx8802_driver *drv) if (drv->advise_acquire) { - core->active_ref++; mutex_lock(&drv->core->lock); + core->active_ref++; if (core->active_type_id == CX88_BOARD_NONE) { core->active_type_id = drv->type_id; drv->advise_acquire(drv); @@ -634,14 +634,14 @@ static int cx8802_request_release(struct cx8802_driver *drv) { struct cx88_core *core = drv->core; + mutex_lock(&drv->core->lock); if (drv->advise_release && --core->active_ref == 0) { - mutex_lock(&drv->core->lock); drv->advise_release(drv); core->active_type_id = CX88_BOARD_NONE; - mutex_unlock(&drv->core->lock); mpeg_dbg(1,"%s() Post release GPIO=%x\n", __FUNCTION__, cx_read(MO_GP0_IO)); } + mutex_unlock(&drv->core->lock); return 0; }