From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751009AbWFXSEX (ORCPT ); Sat, 24 Jun 2006 14:04:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751010AbWFXSEW (ORCPT ); Sat, 24 Jun 2006 14:04:22 -0400 Received: from einhorn.in-berlin.de ([192.109.42.8]:57240 "EHLO einhorn.in-berlin.de") by vger.kernel.org with ESMTP id S1751008AbWFXSEW (ORCPT ); Sat, 24 Jun 2006 14:04:22 -0400 X-Envelope-From: stefanr@s5r6.in-berlin.de Date: Sat, 24 Jun 2006 20:02:59 +0200 (CEST) From: Stefan Richter Subject: Re: [PATCH] ieee1394: dv1394: sem2mutex conversion To: Arjan van de Ven cc: linux1394-devel@lists.sourceforge.net, Ben Collins , linux-kernel@vger.kernel.org In-Reply-To: <1151170975.3181.73.camel@laptopd505.fenrus.org> Message-ID: References: <1151170975.3181.73.camel@laptopd505.fenrus.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; CHARSET=us-ascii Content-Disposition: INLINE X-Spam-Score: (-0.026) AWL,BAYES_40 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org 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 Subject: [PATCH] ieee1394: dv1394: sem2mutex conversion Signed-off-by: Stefan Richter --- 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 #include #include +#include #include #include #include @@ -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;