mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-23 12:43:55 +08:00
ad608fbcf1
The event subscriptions are added to the subscribed event list while
holding a spinlock, but that lock is subsequently released while still
accessing the subscription object. This makes it possible to unsubscribe
the event --- and freeing the subscription object's memory --- while
the subscription object is simultaneously accessed.
Prevent this by adding a mutex to serialise the event subscription and
unsubscription. This also gives a guarantee to the callback ops that the
add op has returned before the del op is called.
This change also results in making the elems field less special:
subscriptions are only added to the event list once they are fully
initialised.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: stable@vger.kernel.org # for 4.14 and up
Fixes: c3b5b0241f ("V4L/DVB: V4L: Events: Add backend")
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
125 lines
3.1 KiB
C
125 lines
3.1 KiB
C
/*
|
|
* v4l2-fh.c
|
|
*
|
|
* V4L2 file handles.
|
|
*
|
|
* Copyright (C) 2009--2010 Nokia Corporation.
|
|
*
|
|
* Contact: Sakari Ailus <sakari.ailus@iki.fi>
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License
|
|
* version 2 as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful, but
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
* General Public License for more details.
|
|
*/
|
|
|
|
#include <linux/bitops.h>
|
|
#include <linux/slab.h>
|
|
#include <linux/export.h>
|
|
#include <media/v4l2-dev.h>
|
|
#include <media/v4l2-fh.h>
|
|
#include <media/v4l2-event.h>
|
|
#include <media/v4l2-ioctl.h>
|
|
#include <media/v4l2-mc.h>
|
|
|
|
void v4l2_fh_init(struct v4l2_fh *fh, struct video_device *vdev)
|
|
{
|
|
fh->vdev = vdev;
|
|
/* Inherit from video_device. May be overridden by the driver. */
|
|
fh->ctrl_handler = vdev->ctrl_handler;
|
|
INIT_LIST_HEAD(&fh->list);
|
|
set_bit(V4L2_FL_USES_V4L2_FH, &fh->vdev->flags);
|
|
/*
|
|
* determine_valid_ioctls() does not know if struct v4l2_fh
|
|
* is used by this driver, but here we do. So enable the
|
|
* prio ioctls here.
|
|
*/
|
|
set_bit(_IOC_NR(VIDIOC_G_PRIORITY), vdev->valid_ioctls);
|
|
set_bit(_IOC_NR(VIDIOC_S_PRIORITY), vdev->valid_ioctls);
|
|
fh->prio = V4L2_PRIORITY_UNSET;
|
|
init_waitqueue_head(&fh->wait);
|
|
INIT_LIST_HEAD(&fh->available);
|
|
INIT_LIST_HEAD(&fh->subscribed);
|
|
fh->sequence = -1;
|
|
mutex_init(&fh->subscribe_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(v4l2_fh_init);
|
|
|
|
void v4l2_fh_add(struct v4l2_fh *fh)
|
|
{
|
|
unsigned long flags;
|
|
|
|
v4l2_prio_open(fh->vdev->prio, &fh->prio);
|
|
spin_lock_irqsave(&fh->vdev->fh_lock, flags);
|
|
list_add(&fh->list, &fh->vdev->fh_list);
|
|
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
|
|
}
|
|
EXPORT_SYMBOL_GPL(v4l2_fh_add);
|
|
|
|
int v4l2_fh_open(struct file *filp)
|
|
{
|
|
struct video_device *vdev = video_devdata(filp);
|
|
struct v4l2_fh *fh = kzalloc(sizeof(*fh), GFP_KERNEL);
|
|
|
|
filp->private_data = fh;
|
|
if (fh == NULL)
|
|
return -ENOMEM;
|
|
v4l2_fh_init(fh, vdev);
|
|
v4l2_fh_add(fh);
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(v4l2_fh_open);
|
|
|
|
void v4l2_fh_del(struct v4l2_fh *fh)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&fh->vdev->fh_lock, flags);
|
|
list_del_init(&fh->list);
|
|
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
|
|
v4l2_prio_close(fh->vdev->prio, fh->prio);
|
|
}
|
|
EXPORT_SYMBOL_GPL(v4l2_fh_del);
|
|
|
|
void v4l2_fh_exit(struct v4l2_fh *fh)
|
|
{
|
|
if (fh->vdev == NULL)
|
|
return;
|
|
v4l_disable_media_source(fh->vdev);
|
|
v4l2_event_unsubscribe_all(fh);
|
|
mutex_destroy(&fh->subscribe_lock);
|
|
fh->vdev = NULL;
|
|
}
|
|
EXPORT_SYMBOL_GPL(v4l2_fh_exit);
|
|
|
|
int v4l2_fh_release(struct file *filp)
|
|
{
|
|
struct v4l2_fh *fh = filp->private_data;
|
|
|
|
if (fh) {
|
|
v4l2_fh_del(fh);
|
|
v4l2_fh_exit(fh);
|
|
kfree(fh);
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(v4l2_fh_release);
|
|
|
|
int v4l2_fh_is_singular(struct v4l2_fh *fh)
|
|
{
|
|
unsigned long flags;
|
|
int is_singular;
|
|
|
|
if (fh == NULL || fh->vdev == NULL)
|
|
return 0;
|
|
spin_lock_irqsave(&fh->vdev->fh_lock, flags);
|
|
is_singular = list_is_singular(&fh->list);
|
|
spin_unlock_irqrestore(&fh->vdev->fh_lock, flags);
|
|
return is_singular;
|
|
}
|
|
EXPORT_SYMBOL_GPL(v4l2_fh_is_singular);
|