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linux-next/drivers/media/dvb-core/dvb_net.h
Nikolaus Schulz 30ad64b8ac [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>
2012-12-27 15:44:21 -02:00

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1.7 KiB
C

/*
* dvb_net.h
*
* Copyright (C) 2001 Ralph Metzler for convergence integrated media GmbH
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1
* of the License, or (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*/
#ifndef _DVB_NET_H_
#define _DVB_NET_H_
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include "dvbdev.h"
#define DVB_NET_DEVICES_MAX 10
#ifdef CONFIG_DVB_NET
struct dvb_net {
struct dvb_device *dvbdev;
struct net_device *device[DVB_NET_DEVICES_MAX];
int state[DVB_NET_DEVICES_MAX];
unsigned int exit:1;
struct dmx_demux *demux;
struct mutex ioctl_mutex;
};
void dvb_net_release(struct dvb_net *);
int dvb_net_init(struct dvb_adapter *, struct dvb_net *, struct dmx_demux *);
#else
struct dvb_net {
struct dvb_device *dvbdev;
};
static inline void dvb_net_release(struct dvb_net *dvbnet)
{
}
static inline int dvb_net_init(struct dvb_adapter *adap,
struct dvb_net *dvbnet, struct dmx_demux *dmx)
{
return 0;
}
#endif /* ifdef CONFIG_DVB_NET */
#endif