kernel-fxtec-pro1x/drivers/media/video/video-buf-dvb.c
Rafael J. Wysocki 8314418629 Freezer: make kernel threads nonfreezable by default
Currently, the freezer treats all tasks as freezable, except for the kernel
threads that explicitly set the PF_NOFREEZE flag for themselves.  This
approach is problematic, since it requires every kernel thread to either
set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't
care for the freezing of tasks at all.

It seems better to only require the kernel threads that want to or need to
be frozen to use some freezer-related code and to remove any
freezer-related code from the other (nonfreezable) kernel threads, which is
done in this patch.

The patch causes all kernel threads to be nonfreezable by default (ie.  to
have PF_NOFREEZE set by default) and introduces the set_freezable()
function that should be called by the freezable kernel threads in order to
unset PF_NOFREEZE.  It also makes all of the currently freezable kernel
threads call set_freezable(), so it shouldn't cause any (intentional)
change of behaviour to appear.  Additionally, it updates documentation to
describe the freezing of tasks more accurately.

[akpm@linux-foundation.org: build fixes]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:02 -07:00

255 lines
6.6 KiB
C

/*
*
* some helper function for simple DVB cards which simply DMA the
* complete transport stream and let the computer sort everything else
* (i.e. we are using the software demux, ...). Also uses the
* video-buf to manage DMA buffers.
*
* (c) 2004 Gerd Knorr <kraxel@bytesex.org> [SUSE Labs]
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/kthread.h>
#include <linux/file.h>
#include <linux/freezer.h>
#include <media/video-buf.h>
#include <media/video-buf-dvb.h>
/* ------------------------------------------------------------------ */
MODULE_AUTHOR("Gerd Knorr <kraxel@bytesex.org> [SuSE Labs]");
MODULE_LICENSE("GPL");
static unsigned int debug = 0;
module_param(debug, int, 0644);
MODULE_PARM_DESC(debug,"enable debug messages");
#define dprintk(fmt, arg...) if (debug) \
printk(KERN_DEBUG "%s/dvb: " fmt, dvb->name , ## arg)
/* ------------------------------------------------------------------ */
static int videobuf_dvb_thread(void *data)
{
struct videobuf_dvb *dvb = data;
struct videobuf_buffer *buf;
unsigned long flags;
int err;
dprintk("dvb thread started\n");
set_freezable();
videobuf_read_start(&dvb->dvbq);
for (;;) {
/* fetch next buffer */
buf = list_entry(dvb->dvbq.stream.next,
struct videobuf_buffer, stream);
list_del(&buf->stream);
err = videobuf_waiton(buf,0,1);
BUG_ON(0 != err);
/* no more feeds left or stop_feed() asked us to quit */
if (0 == dvb->nfeeds)
break;
if (kthread_should_stop())
break;
try_to_freeze();
/* feed buffer data to demux */
if (buf->state == STATE_DONE)
dvb_dmx_swfilter(&dvb->demux, buf->dma.vmalloc,
buf->size);
/* requeue buffer */
list_add_tail(&buf->stream,&dvb->dvbq.stream);
spin_lock_irqsave(dvb->dvbq.irqlock,flags);
dvb->dvbq.ops->buf_queue(&dvb->dvbq,buf);
spin_unlock_irqrestore(dvb->dvbq.irqlock,flags);
}
videobuf_read_stop(&dvb->dvbq);
dprintk("dvb thread stopped\n");
/* Hmm, linux becomes *very* unhappy without this ... */
while (!kthread_should_stop()) {
set_current_state(TASK_INTERRUPTIBLE);
schedule();
}
return 0;
}
static int videobuf_dvb_start_feed(struct dvb_demux_feed *feed)
{
struct dvb_demux *demux = feed->demux;
struct videobuf_dvb *dvb = demux->priv;
int rc;
if (!demux->dmx.frontend)
return -EINVAL;
mutex_lock(&dvb->lock);
dvb->nfeeds++;
rc = dvb->nfeeds;
if (NULL != dvb->thread)
goto out;
dvb->thread = kthread_run(videobuf_dvb_thread,
dvb, "%s dvb", dvb->name);
if (IS_ERR(dvb->thread)) {
rc = PTR_ERR(dvb->thread);
dvb->thread = NULL;
}
out:
mutex_unlock(&dvb->lock);
return rc;
}
static int videobuf_dvb_stop_feed(struct dvb_demux_feed *feed)
{
struct dvb_demux *demux = feed->demux;
struct videobuf_dvb *dvb = demux->priv;
int err = 0;
mutex_lock(&dvb->lock);
dvb->nfeeds--;
if (0 == dvb->nfeeds && NULL != dvb->thread) {
// FIXME: cx8802_cancel_buffers(dev);
err = kthread_stop(dvb->thread);
dvb->thread = NULL;
}
mutex_unlock(&dvb->lock);
return err;
}
/* ------------------------------------------------------------------ */
int videobuf_dvb_register(struct videobuf_dvb *dvb,
struct module *module,
void *adapter_priv,
struct device *device)
{
int result;
mutex_init(&dvb->lock);
/* register adapter */
result = dvb_register_adapter(&dvb->adapter, dvb->name, module, device);
if (result < 0) {
printk(KERN_WARNING "%s: dvb_register_adapter failed (errno = %d)\n",
dvb->name, result);
goto fail_adapter;
}
dvb->adapter.priv = adapter_priv;
/* register frontend */
result = dvb_register_frontend(&dvb->adapter, dvb->frontend);
if (result < 0) {
printk(KERN_WARNING "%s: dvb_register_frontend failed (errno = %d)\n",
dvb->name, result);
goto fail_frontend;
}
/* register demux stuff */
dvb->demux.dmx.capabilities =
DMX_TS_FILTERING | DMX_SECTION_FILTERING |
DMX_MEMORY_BASED_FILTERING;
dvb->demux.priv = dvb;
dvb->demux.filternum = 256;
dvb->demux.feednum = 256;
dvb->demux.start_feed = videobuf_dvb_start_feed;
dvb->demux.stop_feed = videobuf_dvb_stop_feed;
result = dvb_dmx_init(&dvb->demux);
if (result < 0) {
printk(KERN_WARNING "%s: dvb_dmx_init failed (errno = %d)\n",
dvb->name, result);
goto fail_dmx;
}
dvb->dmxdev.filternum = 256;
dvb->dmxdev.demux = &dvb->demux.dmx;
dvb->dmxdev.capabilities = 0;
result = dvb_dmxdev_init(&dvb->dmxdev, &dvb->adapter);
if (result < 0) {
printk(KERN_WARNING "%s: dvb_dmxdev_init failed (errno = %d)\n",
dvb->name, result);
goto fail_dmxdev;
}
dvb->fe_hw.source = DMX_FRONTEND_0;
result = dvb->demux.dmx.add_frontend(&dvb->demux.dmx, &dvb->fe_hw);
if (result < 0) {
printk(KERN_WARNING "%s: add_frontend failed (DMX_FRONTEND_0, errno = %d)\n",
dvb->name, result);
goto fail_fe_hw;
}
dvb->fe_mem.source = DMX_MEMORY_FE;
result = dvb->demux.dmx.add_frontend(&dvb->demux.dmx, &dvb->fe_mem);
if (result < 0) {
printk(KERN_WARNING "%s: add_frontend failed (DMX_MEMORY_FE, errno = %d)\n",
dvb->name, result);
goto fail_fe_mem;
}
result = dvb->demux.dmx.connect_frontend(&dvb->demux.dmx, &dvb->fe_hw);
if (result < 0) {
printk(KERN_WARNING "%s: connect_frontend failed (errno = %d)\n",
dvb->name, result);
goto fail_fe_conn;
}
/* register network adapter */
dvb_net_init(&dvb->adapter, &dvb->net, &dvb->demux.dmx);
return 0;
fail_fe_conn:
dvb->demux.dmx.remove_frontend(&dvb->demux.dmx, &dvb->fe_mem);
fail_fe_mem:
dvb->demux.dmx.remove_frontend(&dvb->demux.dmx, &dvb->fe_hw);
fail_fe_hw:
dvb_dmxdev_release(&dvb->dmxdev);
fail_dmxdev:
dvb_dmx_release(&dvb->demux);
fail_dmx:
dvb_unregister_frontend(dvb->frontend);
fail_frontend:
dvb_frontend_detach(dvb->frontend);
dvb_unregister_adapter(&dvb->adapter);
fail_adapter:
return result;
}
void videobuf_dvb_unregister(struct videobuf_dvb *dvb)
{
dvb_net_release(&dvb->net);
dvb->demux.dmx.remove_frontend(&dvb->demux.dmx, &dvb->fe_mem);
dvb->demux.dmx.remove_frontend(&dvb->demux.dmx, &dvb->fe_hw);
dvb_dmxdev_release(&dvb->dmxdev);
dvb_dmx_release(&dvb->demux);
dvb_unregister_frontend(dvb->frontend);
dvb_frontend_detach(dvb->frontend);
dvb_unregister_adapter(&dvb->adapter);
}
EXPORT_SYMBOL(videobuf_dvb_register);
EXPORT_SYMBOL(videobuf_dvb_unregister);
/* ------------------------------------------------------------------ */
/*
* Local variables:
* c-basic-offset: 8
* compile-command: "make DVB=1"
* End:
*/