From 30ad64b8ac539459f8975aa186421ef3db0bb5cb Mon Sep 17 00:00:00 2001 From: Nikolaus Schulz Date: Sun, 23 Dec 2012 18:49:07 -0300 Subject: [media] dvb: push down ioctl lock in dvb_usercopy MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Since most dvb ioctls wrap their real work with dvb_usercopy, the static mutex used in dvb_usercopy effectively is a global lock for dvb ioctls. Unfortunately, frontend ioctls can be blocked by the frontend thread for several seconds; this leads to unacceptable lock contention. Mitigate that by pushing the mutex from dvb_usercopy down to the individual, device specific ioctls. There are 10 such ioctl functions using dvb_usercopy, either calling it directly, or via the trivial wrapper dvb_generic_ioctl. The following already employ their own locking and look safe: • dvb_demux_ioctl (as per dvb_demux_do_ioctl) • dvb_dvr_ioctl (as per dvb_dvr_do_ioctl) • dvb_osd_ioctl (as per single non-trivial callee) • fdtv_ca_ioctl (as per callees) • dvb_frontend_ioctl The following functions do not, and are thus changed to use a device specific mutex: • dvb_net_ioctl (as per dvb_net_do_ioctl) • dvb_ca_en50221_io_ioctl (as per dvb_ca_en50221_io_do_ioctl) • dvb_video_ioctl • dvb_audio_ioctl • dvb_ca_ioctl Signed-off-by: Nikolaus Schulz Signed-off-by: Michael Krufky Signed-off-by: Mauro Carvalho Chehab --- drivers/media/dvb-core/dvbdev.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'drivers/media/dvb-core/dvbdev.c') diff --git a/drivers/media/dvb-core/dvbdev.c b/drivers/media/dvb-core/dvbdev.c index d33101a..401ef64 100644 --- a/drivers/media/dvb-core/dvbdev.c +++ b/drivers/media/dvb-core/dvbdev.c @@ -418,10 +418,8 @@ int dvb_usercopy(struct file *file, } /* call driver */ - mutex_lock(&dvbdev_mutex); if ((err = func(file, cmd, parg)) == -ENOIOCTLCMD) err = -ENOTTY; - mutex_unlock(&dvbdev_mutex); if (err < 0) goto out; -- cgit v1.1