[media] dvb: push down ioctl lock in dvb_usercopy
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 <schulz@macnetix.de>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/media/pci/ttpci/av7110.c b/drivers/media/pci/ttpci/av7110.c
index 4bd8bd5..2f54e2b 100644
--- a/drivers/media/pci/ttpci/av7110.c
+++ b/drivers/media/pci/ttpci/av7110.c
@@ -2723,6 +2723,8 @@
if (ret < 0)
goto err_av7110_exit_v4l_12;
+ mutex_init(&av7110->ioctl_mutex);
+
#if defined(CONFIG_INPUT_EVDEV) || defined(CONFIG_INPUT_EVDEV_MODULE)
av7110_ir_init(av7110);
#endif