On Tue, Jan 08, 2013 at 12:05:47PM +0530, Soby Mathew wrote: > Hi Everyone, > I have a doubt regarding about the global mutex lock in > dvb_usercopy(drivers/media/dvb-core/dvbdev.c, line 382) . > > > /* call driver */ > mutex_lock(&dvbdev_mutex); > if ((err = func(file, cmd, parg)) == -ENOIOCTLCMD) > err = -EINVAL; > mutex_unlock(&dvbdev_mutex); > > > Why is this mutex needed? When I check similar functions like > video_usercopy, this kind of global locking is not present when func() > is called. I cannot say anything about video_usercopy(), but as it happens, there's a patch[1] queued for Linux 3.9 that will hopefully replace the mutex in dvb_usercopy() with more fine-grained locking. Nikolaus [1] http://git.linuxtv.org/media_tree.git/commit/30ad64b8ac539459f8975aa186421ef3db0bb5cb -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
