On 24 Jun, Arjan van de Ven wrote:
> On Sat, 2006-06-24 at 19:37 +0200, Stefan Richter wrote:
>>
>> - if (down_trylock(&video->sem)) {
>> + if (mutex_trylock(&video->mtx)) {
>
> this is a bug!
>
> mutex_trylock follows the spinlock trylock convention, not the semaphore
> trylock convention!!!
Oops, thanks.
------- 8< -------
From: Stefan Richter <[email protected]>
Subject: [PATCH] ieee1394: dv1394: sem2mutex conversion
Signed-off-by: Stefan Richter <[email protected]>
---
drivers/ieee1394/dv1394-private.h | 6 ++---
drivers/ieee1394/dv1394.c | 31 +++++++++++++++---------------
2 files changed, 19 insertions(+), 18 deletions(-)
Index: linux/drivers/ieee1394/dv1394-private.h
===================================================================
--- linux.orig/drivers/ieee1394/dv1394-private.h 2006-06-24 19:18:07.000000000 +0200
+++ linux/drivers/ieee1394/dv1394-private.h 2006-06-24 19:18:31.000000000 +0200
@@ -460,7 +460,7 @@ struct video_card {
int dma_running;
/*
- 3) the sleeping semaphore 'sem' - this is used from process context only,
+ 3) the sleeping mutex 'mtx' - this is used from process context only,
to serialize various operations on the video_card. Even though only one
open() is allowed, we still need to prevent multiple threads of execution
from entering calls like read, write, ioctl, etc.
@@ -468,9 +468,9 @@ struct video_card {
I honestly can't think of a good reason to use dv1394 from several threads
at once, but we need to serialize anyway to prevent oopses =).
- NOTE: if you need both spinlock and sem, take sem first to avoid deadlock!
+ NOTE: if you need both spinlock and mtx, take mtx first to avoid deadlock!
*/
- struct semaphore sem;
+ struct mutex mtx;
/* people waiting for buffer space, please form a line here... */
wait_queue_head_t waitq;
Index: linux/drivers/ieee1394/dv1394.c
===================================================================
--- linux.orig/drivers/ieee1394/dv1394.c 2006-06-24 19:18:28.000000000 +0200
+++ linux/drivers/ieee1394/dv1394.c 2006-06-24 19:58:13.000000000 +0200
@@ -96,6 +96,7 @@
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/smp_lock.h>
+#include <linux/mutex.h>
#include <linux/bitops.h>
#include <asm/byteorder.h>
#include <asm/atomic.h>
@@ -248,7 +249,7 @@ static void frame_delete(struct frame *f
Frame_prepare() must be called OUTSIDE the video->spinlock.
However, frame_prepare() must still be serialized, so
- it should be called WITH the video->sem taken.
+ it should be called WITH the video->mtx taken.
*/
static void frame_prepare(struct video_card *video, unsigned int this_frame)
@@ -1272,7 +1273,7 @@ static int dv1394_mmap(struct file *file
int retval = -EINVAL;
/* serialize mmap */
- down(&video->sem);
+ mutex_lock(&video->mtx);
if ( ! video_card_initialized(video) ) {
retval = do_dv1394_init_default(video);
@@ -1282,7 +1283,7 @@ static int dv1394_mmap(struct file *file
retval = dma_region_mmap(&video->dv_buf, file, vma);
out:
- up(&video->sem);
+ mutex_unlock(&video->mtx);
return retval;
}
@@ -1338,17 +1339,17 @@ static ssize_t dv1394_write(struct file
/* serialize this to prevent multi-threaded mayhem */
if (file->f_flags & O_NONBLOCK) {
- if (down_trylock(&video->sem))
+ if (!mutex_trylock(&video->mtx))
return -EAGAIN;
} else {
- if (down_interruptible(&video->sem))
+ if (mutex_lock_interruptible(&video->mtx))
return -ERESTARTSYS;
}
if ( !video_card_initialized(video) ) {
ret = do_dv1394_init_default(video);
if (ret) {
- up(&video->sem);
+ mutex_unlock(&video->mtx);
return ret;
}
}
@@ -1419,7 +1420,7 @@ static ssize_t dv1394_write(struct file
remove_wait_queue(&video->waitq, &wait);
set_current_state(TASK_RUNNING);
- up(&video->sem);
+ mutex_unlock(&video->mtx);
return ret;
}
@@ -1435,17 +1436,17 @@ static ssize_t dv1394_read(struct file *
/* serialize this to prevent multi-threaded mayhem */
if (file->f_flags & O_NONBLOCK) {
- if (down_trylock(&video->sem))
+ if (!mutex_trylock(&video->mtx))
return -EAGAIN;
} else {
- if (down_interruptible(&video->sem))
+ if (mutex_lock_interruptible(&video->mtx))
return -ERESTARTSYS;
}
if ( !video_card_initialized(video) ) {
ret = do_dv1394_init_default(video);
if (ret) {
- up(&video->sem);
+ mutex_unlock(&video->mtx);
return ret;
}
video->continuity_counter = -1;
@@ -1527,7 +1528,7 @@ static ssize_t dv1394_read(struct file *
remove_wait_queue(&video->waitq, &wait);
set_current_state(TASK_RUNNING);
- up(&video->sem);
+ mutex_unlock(&video->mtx);
return ret;
}
@@ -1548,12 +1549,12 @@ static long dv1394_ioctl(struct file *fi
/* serialize this to prevent multi-threaded mayhem */
if (file->f_flags & O_NONBLOCK) {
- if (down_trylock(&video->sem)) {
+ if (!mutex_trylock(&video->mtx)) {
unlock_kernel();
return -EAGAIN;
}
} else {
- if (down_interruptible(&video->sem)) {
+ if (mutex_lock_interruptible(&video->mtx)) {
unlock_kernel();
return -ERESTARTSYS;
}
@@ -1779,7 +1780,7 @@ static long dv1394_ioctl(struct file *fi
}
out:
- up(&video->sem);
+ mutex_unlock(&video->mtx);
unlock_kernel();
return ret;
}
@@ -2254,7 +2255,7 @@ static int dv1394_init(struct ti_ohci *o
clear_bit(0, &video->open);
spin_lock_init(&video->spinlock);
video->dma_running = 0;
- init_MUTEX(&video->sem);
+ mutex_init(&video->mtx);
init_waitqueue_head(&video->waitq);
video->fasync = NULL;
-
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