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Message-ID: <4628B6A3.8010800@fr.ibm.com>
Date: Fri, 20 Apr 2007 14:48:35 +0200
From: Cedric Le Goater <clg@...ibm.com>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
CC: "<Andrew Morton" <akpm@...l.org>, containers@...ts.osdl.org,
Oleg Nesterov <oleg@...sign.ru>,
Christoph Hellwig <hch@...radead.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] saa7134-tvaudio: Convert to kthread API.
Eric W. Biederman wrote:
> From: Eric W. Biederman <ebiederm@...ssion.com> - unquoted
>
> It is my goal to replace all kernel code that handles signals
> from user space, calls kernel_thread or calls daemonize. All
> of which the kthread_api makes unncessary. Handling signals
> from user space is a maintenance problem becuase using a
> kernel thread is an implementation detail and if user space
> cares it does not allow us to change the implementation. Calling
> daemonize is a problem because it has to undo a continually changing
> set of state generated by user space, requiring the implemetation
> to change continually. kernel_thread is a problem because it
> returns a pid_t value. Numeric pids are inherently racy and
> in the presence of a pid namespace they are no longer global
> making them useless for general use in the kernel.
>
> So this patch renames the pid member of struct saa7134_thread
> started and changes it's type from pid_t to int. All it
> has ever been used for is to detect if the kernel thread
> is has been started so this works.
>
> allow_signal(SIGTERM) and the calls to signal_pending have
> been removed they are needed for the driver to operation.
>
> The startup of tvaudio_thread and tvaudio_thread_dep have
> been modified to use kthread_run instead of a combination
> of kernel_thread and daemonize.
>
> The result is code that is slightly simpler and more
> maintainable.
Here's a refreshed attempt using kthread_should_stop().
Unfortunately, not tested bc we don't have the hardware.
cheers,
C.
From: Sukadev Bhattiprolu <sukadev@...ibm.com>
Replace kernel_thread() with kthread_run() since kernel_thread()
is deprecated in drivers/modules. Also remove signalling code
as it is not needed in the driver.
Signed-off-by: Sukadev Bhattiprolu <sukadev@...ibm.com>
Signed-off-by: Cedric Le Goater <clg@...ibm.com>
Cc: Mauro Carvalho Chehab <mchehab@...radead.org>
Cc: Containers@...ts.osdl.org
Cc: video4linux-list@...hat.com
Cc: v4l-dvb-maintainer@...uxtv.org
---
drivers/media/video/saa7134/saa7134-tvaudio.c | 45 +++++++++++++-------------
drivers/media/video/saa7134/saa7134.h | 4 --
2 files changed, 24 insertions(+), 25 deletions(-)
Index: 2.6.21-rc6-mm1/drivers/media/video/saa7134/saa7134.h
===================================================================
--- 2.6.21-rc6-mm1.orig/drivers/media/video/saa7134/saa7134.h
+++ 2.6.21-rc6-mm1/drivers/media/video/saa7134/saa7134.h
@@ -324,10 +324,8 @@ struct saa7134_pgtable {
/* tvaudio thread status */
struct saa7134_thread {
- pid_t pid;
- struct completion exit;
+ struct task_struct * task;
wait_queue_head_t wq;
- unsigned int shutdown;
unsigned int scan1;
unsigned int scan2;
unsigned int mode;
Index: 2.6.21-rc6-mm1/drivers/media/video/saa7134/saa7134-tvaudio.c
===================================================================
--- 2.6.21-rc6-mm1.orig/drivers/media/video/saa7134/saa7134-tvaudio.c
+++ 2.6.21-rc6-mm1/drivers/media/video/saa7134/saa7134-tvaudio.c
@@ -27,6 +27,7 @@
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/delay.h>
+#include <linux/kthread.h>
#include <asm/div64.h>
#include "saa7134-reg.h"
@@ -344,16 +345,22 @@ static int tvaudio_sleep(struct saa7134_
DECLARE_WAITQUEUE(wait, current);
add_wait_queue(&dev->thread.wq, &wait);
- if (dev->thread.scan1 == dev->thread.scan2 && !dev->thread.shutdown) {
+
+ set_current_state(TASK_INTERRUPTIBLE);
+
+ if (dev->thread.scan1 == dev->thread.scan2 && !kthread_should_stop()) {
if (timeout < 0) {
- set_current_state(TASK_INTERRUPTIBLE);
schedule();
} else {
schedule_timeout_interruptible
(msecs_to_jiffies(timeout));
}
}
+
+ set_current_state(TASK_RUNNING);
+
remove_wait_queue(&dev->thread.wq, &wait);
+
return dev->thread.scan1 != dev->thread.scan2;
}
@@ -505,11 +512,9 @@ static int tvaudio_thread(void *data)
unsigned int i, audio, nscan;
int max1,max2,carrier,rx,mode,lastmode,default_carrier;
- daemonize("%s", dev->name);
- allow_signal(SIGTERM);
for (;;) {
tvaudio_sleep(dev,-1);
- if (dev->thread.shutdown || signal_pending(current))
+ if (kthread_should_stop())
goto done;
restart:
@@ -618,7 +623,7 @@ static int tvaudio_thread(void *data)
for (;;) {
if (tvaudio_sleep(dev,5000))
goto restart;
- if (dev->thread.shutdown || signal_pending(current))
+ if (kthread_should_stop())
break;
if (UNSET == dev->thread.mode) {
rx = tvaudio_getstereo(dev,&tvaudio[i]);
@@ -634,7 +639,6 @@ static int tvaudio_thread(void *data)
}
done:
- complete_and_exit(&dev->thread.exit, 0);
return 0;
}
@@ -782,9 +786,6 @@ static int tvaudio_thread_ddep(void *dat
struct saa7134_dev *dev = data;
u32 value, norms, clock;
- daemonize("%s", dev->name);
- allow_signal(SIGTERM);
-
clock = saa7134_boards[dev->board].audio_clock;
if (UNSET != audio_clock_override)
clock = audio_clock_override;
@@ -796,7 +797,7 @@ static int tvaudio_thread_ddep(void *dat
for (;;) {
tvaudio_sleep(dev,-1);
- if (dev->thread.shutdown || signal_pending(current))
+ if (kthread_should_stop())
goto done;
restart:
@@ -876,7 +877,6 @@ static int tvaudio_thread_ddep(void *dat
}
done:
- complete_and_exit(&dev->thread.exit, 0);
return 0;
}
@@ -986,15 +986,16 @@ int saa7134_tvaudio_init2(struct saa7134
break;
}
- dev->thread.pid = -1;
+ dev->thread.task = NULL;
if (my_thread) {
/* start tvaudio thread */
init_waitqueue_head(&dev->thread.wq);
- init_completion(&dev->thread.exit);
- dev->thread.pid = kernel_thread(my_thread,dev,0);
- if (dev->thread.pid < 0)
- printk(KERN_WARNING "%s: kernel_thread() failed\n",
+ dev->thread.task = kthread_run(my_thread, dev, dev->name);
+ if (IS_ERR(dev->thread.task)) {
+ printk(KERN_WARNING "%s: failed to create kthread\n",
dev->name);
+ dev->thread.task = NULL;
+ }
saa7134_tvaudio_do_scan(dev);
}
@@ -1005,10 +1006,10 @@ int saa7134_tvaudio_init2(struct saa7134
int saa7134_tvaudio_fini(struct saa7134_dev *dev)
{
/* shutdown tvaudio thread */
- if (dev->thread.pid >= 0) {
- dev->thread.shutdown = 1;
- wake_up_interruptible(&dev->thread.wq);
- wait_for_completion(&dev->thread.exit);
+ if (dev->thread.task) {
+ /* kthread_stop() wakes up the thread */
+ kthread_stop(dev->thread.task);
+ dev->thread.task = NULL;
}
saa_andorb(SAA7134_ANALOG_IO_SELECT, 0x07, 0x00); /* LINE1 */
return 0;
@@ -1020,7 +1021,7 @@ int saa7134_tvaudio_do_scan(struct saa71
dprintk("sound IF not in use, skipping scan\n");
dev->automute = 0;
saa7134_tvaudio_setmute(dev);
- } else if (dev->thread.pid >= 0) {
+ } else if (dev->thread.task) {
dev->thread.mode = UNSET;
dev->thread.scan2++;
wake_up_interruptible(&dev->thread.wq);
-
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