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.
This global lock will prevent any other ioctl call from being executed
unless the previous blocking ioctl call has returned. If we need to
have a lock why not make it file handle specific ?
Thanks for your help.
Best Regards
Soby Mathew
Best Regards
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