kernel.git/drivers/media/usb/cpia2, branch linux-4.5.y

[media] media: fix waitqueue_active without memory barrier in cpia2 driver

2015-11-17T16:55:06Z

cpia2_usb_disconnect() seems to be missing a memory barrier which might cause the waker to not notice the waiter and miss sending a wake_up as in the following figure. cpia2_usb_disconnect sync ------------------------------------------------------------------------ mutex_unlock(&cam->v4l2_lock); if (waitqueue_active(&cam->wq_stream)) /* The CPU might reorder the test for the waitqueue up here, before prior writes complete */ /* wait_event_interruptible */ /* __wait_event_interruptible */ /* ___wait_event */ long __int = prepare_to_wait_event( &wq, &__wait, state); if (!cam->streaming || frame->status == FRAME_READY) cam->curbuff->status = FRAME_READY; cam->curbuff->length = 0; schedule() ------------------------------------------------------------------------ The attached patch removes the call to waitqueue_active() leaving just wake_up() behind. This fixes the problem because the call to spin_lock_irqsave() in wake_up() will be an ACQUIRE operation. I found this issue when I was looking through the linux source code for places calling waitqueue_active() before wake_up*(), but without preceding memory barriers, after sending a patch to fix a similar issue in drivers/tty/n_tty.c (Details about the original issue can be found here: https://lkml.org/lkml/2015/9/28/849). Signed-off-by: Kosuke Tatsukawa Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab

[media] media: remove the setting of the flag V4L2_FL_USE_FH_PRIO

2014-07-04T19:14:59Z

Since all the drivers that use `struct v4l2_fh' use the core priority checking, the setting of the flag in the drivers can be removed. Signed-off-by: Ramakrishnan Muthukrishnan Reviewed-by: Hans Verkuil Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab

[media] media: Change variable type to bool

2013-10-17T14:24:35Z

The variable frame_ready is only assigned the values true and false. Change its type to bool. The simplified semantic patch that find this problem is as follows (http://coccinelle.lip6.fr/): @exists@ type T; identifier b; @@ - T + bool b = ...; ... when any b = \(true\|false\) Signed-off-by: Peter Senna Tschudin Signed-off-by: Mauro Carvalho Chehab

[media] v4l: Tell user space we're using monotonic timestamps

2012-12-21T13:20:51Z

Set buffer timestamp flags for videobuf, videobuf2 and drivers that use neither. Signed-off-by: Sakari Ailus Acked-by: Laurent Pinchart Acked-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab

[media] v4l: Convert drivers to use monotonic timestamps

2012-12-21T12:56:43Z

Convert drivers using wall clock time (CLOCK_REALTIME) to timestamp from the monotonic timer (CLOCK_MONOTONIC). Signed-off-by: Sakari Ailus Acked-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab

[media] v4l2: make vidioc_s_jpegcomp const

2012-09-26T13:43:04Z

Write-only ioctls should have a const argument in the ioctl op. Do this conversion for vidioc_s_jpegcomp. Adding const for write-only ioctls was decided during the 2012 Media Workshop. Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab

[media] rename most media/video usb drivers to media/usb

2012-08-15T19:25:07Z

Rename all USB drivers with their own directory under drivers/media/video into drivers/media/usb and update the building system. Signed-off-by: Mauro Carvalho Chehab