diff mbox

[v5] videobuf2: Add missing lock held on vb2_fop_relase

Message ID 1383726282-25668-1-git-send-email-ricardo.ribalda@gmail.com (mailing list archive)
State Superseded, archived
Headers

Commit Message

Ricardo Ribalda Delgado Nov. 6, 2013, 8:24 a.m. UTC 
  From: Ricardo Ribalda <ricardo.ribalda@gmail.com>

vb2_fop_relase does not held the lock although it is modifying the
queue->owner field.

This could lead to race conditions on the vb2_perform_io function
when multiple applications are accessing the video device via
read/write API:

[ 308.297741] BUG: unable to handle kernel NULL pointer dereference at
0000000000000260
[ 308.297759] IP: [<ffffffffa07a9fd2>] vb2_perform_fileio+0x372/0x610
[videobuf2_core]
[ 308.297794] PGD 159719067 PUD 158119067 PMD 0
[ 308.297812] Oops: 0000 #1 SMP
[ 308.297826] Modules linked in: qt5023_video videobuf2_dma_sg
qtec_xform videobuf2_vmalloc videobuf2_memops videobuf2_core
qtec_white qtec_mem gpio_xilinx qtec_cmosis qtec_pcie fglrx(PO)
spi_xilinx spi_bitbang qt5023
[ 308.297888] CPU: 1 PID: 2189 Comm: java Tainted: P O 3.11.0-qtec-standard #1
[ 308.297919] Hardware name: QTechnology QT5022/QT5022, BIOS
PM_2.1.0.309 X64 05/23/2013
[ 308.297952] task: ffff8801564e1690 ti: ffff88014dc02000 task.ti:
ffff88014dc02000
[ 308.297962] RIP: 0010:[<ffffffffa07a9fd2>] [<ffffffffa07a9fd2>]
vb2_perform_fileio+0x372/0x610 [videobuf2_core]
[ 308.297985] RSP: 0018:ffff88014dc03df8 EFLAGS: 00010202
[ 308.297995] RAX: 0000000000000000 RBX: ffff880158a23000 RCX: dead000000100100
[ 308.298003] RDX: 0000000000000000 RSI: dead000000200200 RDI: 0000000000000000
[ 308.298012] RBP: ffff88014dc03e58 R08: 0000000000000000 R09: 0000000000000001
[ 308.298020] R10: ffffea00051e8380 R11: ffff88014dc03fd8 R12: ffff880158a23070
[ 308.298029] R13: ffff8801549040b8 R14: 0000000000198000 R15: 0000000001887e60
[ 308.298040] FS: 00007f65130d5700(0000) GS:ffff88015ed00000(0000)
knlGS:0000000000000000
[ 308.298049] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 308.298057] CR2: 0000000000000260 CR3: 0000000159630000 CR4: 00000000000007e0
[ 308.298064] Stack:
[ 308.298071] ffff880156416c00 0000000000198000 0000000000000000
ffff880100000001
[ 308.298087] ffff88014dc03f50 00000000810a79ca 0002000000000001
ffff880154904718
[ 308.298101] ffff880156416c00 0000000000198000 ffff880154904338
ffff88014dc03f50
[ 308.298116] Call Trace:
[ 308.298143] [<ffffffffa07aa3c4>] vb2_read+0x14/0x20 [videobuf2_core]
[ 308.298198] [<ffffffffa07aa494>] vb2_fop_read+0xc4/0x120 [videobuf2_core]
[ 308.298252] [<ffffffff8154ee9e>] v4l2_read+0x7e/0xc0
[ 308.298296] [<ffffffff8116e639>] vfs_read+0xa9/0x160
[ 308.298312] [<ffffffff8116e882>] SyS_read+0x52/0xb0
[ 308.298328] [<ffffffff81784179>] tracesys+0xd0/0xd5
[ 308.298335] Code: e5 d6 ff ff 83 3d be 24 00 00 04 89 c2 4c 8b 45 b0
44 8b 4d b8 0f 8f 20 02 00 00 85 d2 75 32 83 83 78 03 00 00 01 4b 8b
44 c5 48 <8b> 88 60 02 00 00 85 c9 0f 84 b0 00 00 00 8b 40 58 89 c2 41
89
[ 308.298487] RIP [<ffffffffa07a9fd2>] vb2_perform_fileio+0x372/0x610
[videobuf2_core]
[ 308.298507] RSP <ffff88014dc03df8>
[ 308.298514] CR2: 0000000000000260
[ 308.298526] ---[ end trace e8f01717c96d1e41 ]---

Signed-off-by: Ricardo Ribalda <ricardo.ribalda@gmail.com>
---

v2: Comments by Sylvester Nawrocki

fimc-capture and fimc-lite where calling vb2_fop_release with the lock held.
Therefore a new __vb2_fop_release function has been created to be used by
drivers that overload the release function.

v3: Comments by Sylvester Nawrocki and Mauro Carvalho Chehab

Use vb2_fop_release_locked instead of __vb2_fop_release

v4: Comments by Sylvester Nawrocki

Rename vb2_fop_release_locked to __vb2_fop_release and fix patch format

v5: Comments by Sylvester Nawrocki and Hans Verkuil

Rename __vb2_fop_release to vb2_fop_release_unlock and rearrange
arguments

 drivers/media/platform/exynos4-is/fimc-capture.c |  2 +-
 drivers/media/platform/exynos4-is/fimc-lite.c    |  2 +-
 drivers/media/v4l2-core/videobuf2-core.c         | 20 +++++++++++++++++++-
 include/media/videobuf2-core.h                   |  1 +
 4 files changed, 22 insertions(+), 3 deletions(-)

Comments

Hans Verkuil Nov. 6, 2013, 9:07 a.m. UTC | #1 
On 11/06/13 09:24, Ricardo Ribalda Delgado wrote:
> From: Ricardo Ribalda <ricardo.ribalda@gmail.com>
> 
> vb2_fop_relase does not held the lock although it is modifying the

Small typo: _relase -> _release

> queue->owner field.
> 
> This could lead to race conditions on the vb2_perform_io function
> when multiple applications are accessing the video device via
> read/write API:
> 
> [ 308.297741] BUG: unable to handle kernel NULL pointer dereference at
> 0000000000000260
> [ 308.297759] IP: [<ffffffffa07a9fd2>] vb2_perform_fileio+0x372/0x610
> [videobuf2_core]
> [ 308.297794] PGD 159719067 PUD 158119067 PMD 0
> [ 308.297812] Oops: 0000 #1 SMP
> [ 308.297826] Modules linked in: qt5023_video videobuf2_dma_sg
> qtec_xform videobuf2_vmalloc videobuf2_memops videobuf2_core
> qtec_white qtec_mem gpio_xilinx qtec_cmosis qtec_pcie fglrx(PO)
> spi_xilinx spi_bitbang qt5023
> [ 308.297888] CPU: 1 PID: 2189 Comm: java Tainted: P O 3.11.0-qtec-standard #1
> [ 308.297919] Hardware name: QTechnology QT5022/QT5022, BIOS
> PM_2.1.0.309 X64 05/23/2013
> [ 308.297952] task: ffff8801564e1690 ti: ffff88014dc02000 task.ti:
> ffff88014dc02000
> [ 308.297962] RIP: 0010:[<ffffffffa07a9fd2>] [<ffffffffa07a9fd2>]
> vb2_perform_fileio+0x372/0x610 [videobuf2_core]
> [ 308.297985] RSP: 0018:ffff88014dc03df8 EFLAGS: 00010202
> [ 308.297995] RAX: 0000000000000000 RBX: ffff880158a23000 RCX: dead000000100100
> [ 308.298003] RDX: 0000000000000000 RSI: dead000000200200 RDI: 0000000000000000
> [ 308.298012] RBP: ffff88014dc03e58 R08: 0000000000000000 R09: 0000000000000001
> [ 308.298020] R10: ffffea00051e8380 R11: ffff88014dc03fd8 R12: ffff880158a23070
> [ 308.298029] R13: ffff8801549040b8 R14: 0000000000198000 R15: 0000000001887e60
> [ 308.298040] FS: 00007f65130d5700(0000) GS:ffff88015ed00000(0000)
> knlGS:0000000000000000
> [ 308.298049] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 308.298057] CR2: 0000000000000260 CR3: 0000000159630000 CR4: 00000000000007e0
> [ 308.298064] Stack:
> [ 308.298071] ffff880156416c00 0000000000198000 0000000000000000
> ffff880100000001
> [ 308.298087] ffff88014dc03f50 00000000810a79ca 0002000000000001
> ffff880154904718
> [ 308.298101] ffff880156416c00 0000000000198000 ffff880154904338
> ffff88014dc03f50
> [ 308.298116] Call Trace:
> [ 308.298143] [<ffffffffa07aa3c4>] vb2_read+0x14/0x20 [videobuf2_core]
> [ 308.298198] [<ffffffffa07aa494>] vb2_fop_read+0xc4/0x120 [videobuf2_core]
> [ 308.298252] [<ffffffff8154ee9e>] v4l2_read+0x7e/0xc0
> [ 308.298296] [<ffffffff8116e639>] vfs_read+0xa9/0x160
> [ 308.298312] [<ffffffff8116e882>] SyS_read+0x52/0xb0
> [ 308.298328] [<ffffffff81784179>] tracesys+0xd0/0xd5
> [ 308.298335] Code: e5 d6 ff ff 83 3d be 24 00 00 04 89 c2 4c 8b 45 b0
> 44 8b 4d b8 0f 8f 20 02 00 00 85 d2 75 32 83 83 78 03 00 00 01 4b 8b
> 44 c5 48 <8b> 88 60 02 00 00 85 c9 0f 84 b0 00 00 00 8b 40 58 89 c2 41
> 89
> [ 308.298487] RIP [<ffffffffa07a9fd2>] vb2_perform_fileio+0x372/0x610
> [videobuf2_core]
> [ 308.298507] RSP <ffff88014dc03df8>
> [ 308.298514] CR2: 0000000000000260
> [ 308.298526] ---[ end trace e8f01717c96d1e41 ]---
> 
> Signed-off-by: Ricardo Ribalda <ricardo.ribalda@gmail.com>
> ---
> 
> v2: Comments by Sylvester Nawrocki
> 
> fimc-capture and fimc-lite where calling vb2_fop_release with the lock held.
> Therefore a new __vb2_fop_release function has been created to be used by
> drivers that overload the release function.
> 
> v3: Comments by Sylvester Nawrocki and Mauro Carvalho Chehab
> 
> Use vb2_fop_release_locked instead of __vb2_fop_release
> 
> v4: Comments by Sylvester Nawrocki
> 
> Rename vb2_fop_release_locked to __vb2_fop_release and fix patch format
> 
> v5: Comments by Sylvester Nawrocki and Hans Verkuil
> 
> Rename __vb2_fop_release to vb2_fop_release_unlock and rearrange
> arguments

I know I suggested the vb2_fop_release_unlock name, but on second thoughts
that's not a good name. I suggest vb2_fop_release_no_lock instead.
'_unlock' suggests that there is a _lock version as well, which isn't the
case here.

After making that change you can add my:

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>

Regards,

	Hans

> 
>  drivers/media/platform/exynos4-is/fimc-capture.c |  2 +-
>  drivers/media/platform/exynos4-is/fimc-lite.c    |  2 +-
>  drivers/media/v4l2-core/videobuf2-core.c         | 20 +++++++++++++++++++-
>  include/media/videobuf2-core.h                   |  1 +
>  4 files changed, 22 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/media/platform/exynos4-is/fimc-capture.c b/drivers/media/platform/exynos4-is/fimc-capture.c
> index fb27ff7..3035e3b 100644
> --- a/drivers/media/platform/exynos4-is/fimc-capture.c
> +++ b/drivers/media/platform/exynos4-is/fimc-capture.c
> @@ -549,7 +549,7 @@ static int fimc_capture_release(struct file *file)
>  		vc->streaming = false;
>  	}
>  
> -	ret = vb2_fop_release(file);
> +	ret = vb2_fop_release_unlock(file);
>  
>  	if (close) {
>  		clear_bit(ST_CAPT_BUSY, &fimc->state);
> diff --git a/drivers/media/platform/exynos4-is/fimc-lite.c b/drivers/media/platform/exynos4-is/fimc-lite.c
> index e5798f7..dc87429 100644
> --- a/drivers/media/platform/exynos4-is/fimc-lite.c
> +++ b/drivers/media/platform/exynos4-is/fimc-lite.c
> @@ -546,7 +546,7 @@ static int fimc_lite_release(struct file *file)
>  		mutex_unlock(&entity->parent->graph_mutex);
>  	}
>  
> -	vb2_fop_release(file);
> +	vb2_fop_release_unlock(file);
>  	pm_runtime_put(&fimc->pdev->dev);
>  	clear_bit(ST_FLITE_SUSPENDED, &fimc->state);
>  
> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
> index 594c75e..2716714 100644
> --- a/drivers/media/v4l2-core/videobuf2-core.c
> +++ b/drivers/media/v4l2-core/videobuf2-core.c
> @@ -2619,18 +2619,36 @@ int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma)
>  }
>  EXPORT_SYMBOL_GPL(vb2_fop_mmap);
>  
> -int vb2_fop_release(struct file *file)
> +static int _vb2_fop_release(struct file *file, struct mutex *lock)
>  {
>  	struct video_device *vdev = video_devdata(file);
>  
>  	if (file->private_data == vdev->queue->owner) {
> +		if (lock)
> +			mutex_lock(lock);
>  		vb2_queue_release(vdev->queue);
>  		vdev->queue->owner = NULL;
> +		if (lock)
> +			mutex_unlock(lock);
>  	}
>  	return v4l2_fh_release(file);
>  }
> +
> +int vb2_fop_release(struct file *file)
> +{
> +	struct video_device *vdev = video_devdata(file);
> +	struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock;
> +
> +	return _vb2_fop_release(file, lock);
> +}
>  EXPORT_SYMBOL_GPL(vb2_fop_release);
>  
> +int vb2_fop_release_unlock(struct file *file)
> +{
> +	return _vb2_fop_release(file, NULL);
> +}
> +EXPORT_SYMBOL_GPL(vb2_fop_release_unlock);
> +
>  ssize_t vb2_fop_write(struct file *file, char __user *buf,
>  		size_t count, loff_t *ppos)
>  {
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index 6781258..6fcb603 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -491,6 +491,7 @@ int vb2_ioctl_expbuf(struct file *file, void *priv,
>  
>  int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma);
>  int vb2_fop_release(struct file *file);
> +int vb2_fop_release_unlock(struct file *file);
>  ssize_t vb2_fop_write(struct file *file, char __user *buf,
>  		size_t count, loff_t *ppos);
>  ssize_t vb2_fop_read(struct file *file, char __user *buf,
> 

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Ricardo Ribalda Delgado Nov. 6, 2013, 9:11 a.m. UTC | #2 
Hello Hans

I will fix both things, but I will wait a couple of hours in case
there is more changes, to avoid spamming the list.

Thanks

On Wed, Nov 6, 2013 at 10:07 AM, Hans Verkuil <hverkuil@xs4all.nl> wrote:
> On 11/06/13 09:24, Ricardo Ribalda Delgado wrote:
>> From: Ricardo Ribalda <ricardo.ribalda@gmail.com>
>>
>> vb2_fop_relase does not held the lock although it is modifying the
>
> Small typo: _relase -> _release
>
>> queue->owner field.
>>
>> This could lead to race conditions on the vb2_perform_io function
>> when multiple applications are accessing the video device via
>> read/write API:
>>
>> [ 308.297741] BUG: unable to handle kernel NULL pointer dereference at
>> 0000000000000260
>> [ 308.297759] IP: [<ffffffffa07a9fd2>] vb2_perform_fileio+0x372/0x610
>> [videobuf2_core]
>> [ 308.297794] PGD 159719067 PUD 158119067 PMD 0
>> [ 308.297812] Oops: 0000 #1 SMP
>> [ 308.297826] Modules linked in: qt5023_video videobuf2_dma_sg
>> qtec_xform videobuf2_vmalloc videobuf2_memops videobuf2_core
>> qtec_white qtec_mem gpio_xilinx qtec_cmosis qtec_pcie fglrx(PO)
>> spi_xilinx spi_bitbang qt5023
>> [ 308.297888] CPU: 1 PID: 2189 Comm: java Tainted: P O 3.11.0-qtec-standard #1
>> [ 308.297919] Hardware name: QTechnology QT5022/QT5022, BIOS
>> PM_2.1.0.309 X64 05/23/2013
>> [ 308.297952] task: ffff8801564e1690 ti: ffff88014dc02000 task.ti:
>> ffff88014dc02000
>> [ 308.297962] RIP: 0010:[<ffffffffa07a9fd2>] [<ffffffffa07a9fd2>]
>> vb2_perform_fileio+0x372/0x610 [videobuf2_core]
>> [ 308.297985] RSP: 0018:ffff88014dc03df8 EFLAGS: 00010202
>> [ 308.297995] RAX: 0000000000000000 RBX: ffff880158a23000 RCX: dead000000100100
>> [ 308.298003] RDX: 0000000000000000 RSI: dead000000200200 RDI: 0000000000000000
>> [ 308.298012] RBP: ffff88014dc03e58 R08: 0000000000000000 R09: 0000000000000001
>> [ 308.298020] R10: ffffea00051e8380 R11: ffff88014dc03fd8 R12: ffff880158a23070
>> [ 308.298029] R13: ffff8801549040b8 R14: 0000000000198000 R15: 0000000001887e60
>> [ 308.298040] FS: 00007f65130d5700(0000) GS:ffff88015ed00000(0000)
>> knlGS:0000000000000000
>> [ 308.298049] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [ 308.298057] CR2: 0000000000000260 CR3: 0000000159630000 CR4: 00000000000007e0
>> [ 308.298064] Stack:
>> [ 308.298071] ffff880156416c00 0000000000198000 0000000000000000
>> ffff880100000001
>> [ 308.298087] ffff88014dc03f50 00000000810a79ca 0002000000000001
>> ffff880154904718
>> [ 308.298101] ffff880156416c00 0000000000198000 ffff880154904338
>> ffff88014dc03f50
>> [ 308.298116] Call Trace:
>> [ 308.298143] [<ffffffffa07aa3c4>] vb2_read+0x14/0x20 [videobuf2_core]
>> [ 308.298198] [<ffffffffa07aa494>] vb2_fop_read+0xc4/0x120 [videobuf2_core]
>> [ 308.298252] [<ffffffff8154ee9e>] v4l2_read+0x7e/0xc0
>> [ 308.298296] [<ffffffff8116e639>] vfs_read+0xa9/0x160
>> [ 308.298312] [<ffffffff8116e882>] SyS_read+0x52/0xb0
>> [ 308.298328] [<ffffffff81784179>] tracesys+0xd0/0xd5
>> [ 308.298335] Code: e5 d6 ff ff 83 3d be 24 00 00 04 89 c2 4c 8b 45 b0
>> 44 8b 4d b8 0f 8f 20 02 00 00 85 d2 75 32 83 83 78 03 00 00 01 4b 8b
>> 44 c5 48 <8b> 88 60 02 00 00 85 c9 0f 84 b0 00 00 00 8b 40 58 89 c2 41
>> 89
>> [ 308.298487] RIP [<ffffffffa07a9fd2>] vb2_perform_fileio+0x372/0x610
>> [videobuf2_core]
>> [ 308.298507] RSP <ffff88014dc03df8>
>> [ 308.298514] CR2: 0000000000000260
>> [ 308.298526] ---[ end trace e8f01717c96d1e41 ]---
>>
>> Signed-off-by: Ricardo Ribalda <ricardo.ribalda@gmail.com>
>> ---
>>
>> v2: Comments by Sylvester Nawrocki
>>
>> fimc-capture and fimc-lite where calling vb2_fop_release with the lock held.
>> Therefore a new __vb2_fop_release function has been created to be used by
>> drivers that overload the release function.
>>
>> v3: Comments by Sylvester Nawrocki and Mauro Carvalho Chehab
>>
>> Use vb2_fop_release_locked instead of __vb2_fop_release
>>
>> v4: Comments by Sylvester Nawrocki
>>
>> Rename vb2_fop_release_locked to __vb2_fop_release and fix patch format
>>
>> v5: Comments by Sylvester Nawrocki and Hans Verkuil
>>
>> Rename __vb2_fop_release to vb2_fop_release_unlock and rearrange
>> arguments
>
> I know I suggested the vb2_fop_release_unlock name, but on second thoughts
> that's not a good name. I suggest vb2_fop_release_no_lock instead.
> '_unlock' suggests that there is a _lock version as well, which isn't the
> case here.
>
> After making that change you can add my:
>
> Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
>
> Regards,
>
>         Hans
>
>>
>>  drivers/media/platform/exynos4-is/fimc-capture.c |  2 +-
>>  drivers/media/platform/exynos4-is/fimc-lite.c    |  2 +-
>>  drivers/media/v4l2-core/videobuf2-core.c         | 20 +++++++++++++++++++-
>>  include/media/videobuf2-core.h                   |  1 +
>>  4 files changed, 22 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/media/platform/exynos4-is/fimc-capture.c b/drivers/media/platform/exynos4-is/fimc-capture.c
>> index fb27ff7..3035e3b 100644
>> --- a/drivers/media/platform/exynos4-is/fimc-capture.c
>> +++ b/drivers/media/platform/exynos4-is/fimc-capture.c
>> @@ -549,7 +549,7 @@ static int fimc_capture_release(struct file *file)
>>               vc->streaming = false;
>>       }
>>
>> -     ret = vb2_fop_release(file);
>> +     ret = vb2_fop_release_unlock(file);
>>
>>       if (close) {
>>               clear_bit(ST_CAPT_BUSY, &fimc->state);
>> diff --git a/drivers/media/platform/exynos4-is/fimc-lite.c b/drivers/media/platform/exynos4-is/fimc-lite.c
>> index e5798f7..dc87429 100644
>> --- a/drivers/media/platform/exynos4-is/fimc-lite.c
>> +++ b/drivers/media/platform/exynos4-is/fimc-lite.c
>> @@ -546,7 +546,7 @@ static int fimc_lite_release(struct file *file)
>>               mutex_unlock(&entity->parent->graph_mutex);
>>       }
>>
>> -     vb2_fop_release(file);
>> +     vb2_fop_release_unlock(file);
>>       pm_runtime_put(&fimc->pdev->dev);
>>       clear_bit(ST_FLITE_SUSPENDED, &fimc->state);
>>
>> diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
>> index 594c75e..2716714 100644
>> --- a/drivers/media/v4l2-core/videobuf2-core.c
>> +++ b/drivers/media/v4l2-core/videobuf2-core.c
>> @@ -2619,18 +2619,36 @@ int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma)
>>  }
>>  EXPORT_SYMBOL_GPL(vb2_fop_mmap);
>>
>> -int vb2_fop_release(struct file *file)
>> +static int _vb2_fop_release(struct file *file, struct mutex *lock)
>>  {
>>       struct video_device *vdev = video_devdata(file);
>>
>>       if (file->private_data == vdev->queue->owner) {
>> +             if (lock)
>> +                     mutex_lock(lock);
>>               vb2_queue_release(vdev->queue);
>>               vdev->queue->owner = NULL;
>> +             if (lock)
>> +                     mutex_unlock(lock);
>>       }
>>       return v4l2_fh_release(file);
>>  }
>> +
>> +int vb2_fop_release(struct file *file)
>> +{
>> +     struct video_device *vdev = video_devdata(file);
>> +     struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock;
>> +
>> +     return _vb2_fop_release(file, lock);
>> +}
>>  EXPORT_SYMBOL_GPL(vb2_fop_release);
>>
>> +int vb2_fop_release_unlock(struct file *file)
>> +{
>> +     return _vb2_fop_release(file, NULL);
>> +}
>> +EXPORT_SYMBOL_GPL(vb2_fop_release_unlock);
>> +
>>  ssize_t vb2_fop_write(struct file *file, char __user *buf,
>>               size_t count, loff_t *ppos)
>>  {
>> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
>> index 6781258..6fcb603 100644
>> --- a/include/media/videobuf2-core.h
>> +++ b/include/media/videobuf2-core.h
>> @@ -491,6 +491,7 @@ int vb2_ioctl_expbuf(struct file *file, void *priv,
>>
>>  int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma);
>>  int vb2_fop_release(struct file *file);
>> +int vb2_fop_release_unlock(struct file *file);
>>  ssize_t vb2_fop_write(struct file *file, char __user *buf,
>>               size_t count, loff_t *ppos);
>>  ssize_t vb2_fop_read(struct file *file, char __user *buf,
>>
>
Sylwester Nawrocki Nov. 6, 2013, 2:46 p.m. UTC | #3 
Hello,

(dropping some unrelated e-mail addresses from Cc)

On 06/11/13 10:07, Hans Verkuil wrote:
> On 11/06/13 09:24, Ricardo Ribalda Delgado wrote:
>> From: Ricardo Ribalda <ricardo.ribalda@gmail.com>
>>
>> vb2_fop_relase does not held the lock although it is modifying the
> 
> Small typo: _relase -> _release
> 
>> queue->owner field.
>>
[...]
>>
>> Signed-off-by: Ricardo Ribalda <ricardo.ribalda@gmail.com>
>> ---
>>
>> v2: Comments by Sylvester Nawrocki
>>
>> fimc-capture and fimc-lite where calling vb2_fop_release with the lock held.
>> Therefore a new __vb2_fop_release function has been created to be used by
>> drivers that overload the release function.
>>
>> v3: Comments by Sylvester Nawrocki and Mauro Carvalho Chehab
>>
>> Use vb2_fop_release_locked instead of __vb2_fop_release
>>
>> v4: Comments by Sylvester Nawrocki
>>
>> Rename vb2_fop_release_locked to __vb2_fop_release and fix patch format
>>
>> v5: Comments by Sylvester Nawrocki and Hans Verkuil
>>
>> Rename __vb2_fop_release to vb2_fop_release_unlock and rearrange
>> arguments
> 
> I know I suggested the vb2_fop_release_unlock name, but on second thoughts
> that's not a good name. I suggest vb2_fop_release_no_lock instead.
> '_unlock' suggests that there is a _lock version as well, which isn't the
> case here.

Yes. Sorry, but to me vb2_fop_release_no_lock() looks s bit ugly.
Couldn't we just use double underscore prefix instead of _no_lock postfix,
as is commonly done in the kernel ?
Grep reveals almost no use of "_no_lock" in function names.

Thanks,
Sylwester
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Hans Verkuil Nov. 6, 2013, 2:51 p.m. UTC | #4 
On 11/06/13 15:46, Sylwester Nawrocki wrote:
> Hello,
> 
> (dropping some unrelated e-mail addresses from Cc)
> 
> On 06/11/13 10:07, Hans Verkuil wrote:
>> On 11/06/13 09:24, Ricardo Ribalda Delgado wrote:
>>> From: Ricardo Ribalda <ricardo.ribalda@gmail.com>
>>>
>>> vb2_fop_relase does not held the lock although it is modifying the
>>
>> Small typo: _relase -> _release
>>
>>> queue->owner field.
>>>
> [...]
>>>
>>> Signed-off-by: Ricardo Ribalda <ricardo.ribalda@gmail.com>
>>> ---
>>>
>>> v2: Comments by Sylvester Nawrocki
>>>
>>> fimc-capture and fimc-lite where calling vb2_fop_release with the lock held.
>>> Therefore a new __vb2_fop_release function has been created to be used by
>>> drivers that overload the release function.
>>>
>>> v3: Comments by Sylvester Nawrocki and Mauro Carvalho Chehab
>>>
>>> Use vb2_fop_release_locked instead of __vb2_fop_release
>>>
>>> v4: Comments by Sylvester Nawrocki
>>>
>>> Rename vb2_fop_release_locked to __vb2_fop_release and fix patch format
>>>
>>> v5: Comments by Sylvester Nawrocki and Hans Verkuil
>>>
>>> Rename __vb2_fop_release to vb2_fop_release_unlock and rearrange
>>> arguments
>>
>> I know I suggested the vb2_fop_release_unlock name, but on second thoughts
>> that's not a good name. I suggest vb2_fop_release_no_lock instead.
>> '_unlock' suggests that there is a _lock version as well, which isn't the
>> case here.
> 
> Yes. Sorry, but to me vb2_fop_release_no_lock() looks s bit ugly.
> Couldn't we just use double underscore prefix instead of _no_lock postfix,
> as is commonly done in the kernel ?

I'm not keen on that since we then end up with a no-prefix version, a '_'
version and a '__' version. A bit obscure IMHO.

How about just exporting the _vb2_fop_release function and pass a NULL
pointer as lock?

> Grep reveals almost no use of "_no_lock" in function names.

Usually the version without prefix doesn't lock, and you have a _lock
version that does lock. Unfortunately, we couldn't use that here.

Regards,

	Hans
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Sylwester Nawrocki Nov. 6, 2013, 3:22 p.m. UTC | #5 
On 06/11/13 15:51, Hans Verkuil wrote:
>>>> Rename __vb2_fop_release to vb2_fop_release_unlock and rearrange
>>>> >>> arguments
>>> >>
>>> >> I know I suggested the vb2_fop_release_unlock name, but on second thoughts
>>> >> that's not a good name. I suggest vb2_fop_release_no_lock instead.
>>> >> '_unlock' suggests that there is a _lock version as well, which isn't the
>>> >> case here.
>> > 
>> > Yes. Sorry, but to me vb2_fop_release_no_lock() looks s bit ugly.
>> > Couldn't we just use double underscore prefix instead of _no_lock postfix,
>> > as is commonly done in the kernel ?
> I'm not keen on that since we then end up with a no-prefix version, a '_'
> version and a '__' version. A bit obscure IMHO.
> 
> How about just exporting the _vb2_fop_release function and pass a NULL
> pointer as lock?

Sounds OK to me.

>> > Grep reveals almost no use of "_no_lock" in function names.
>
> Usually the version without prefix doesn't lock, and you have a _lock
> version that does lock. Unfortunately, we couldn't use that here.

Perhaps I'm misunderstanding something, but isn't it the opposite,
e.g. foo() which does lock, and __foo() that doesn't ?

So having a set of functions like:

/* locks */
int vb2_fop_release(struct file *file)

/* locks conditionally */
int _vb2_fop_release(struct file *file, struct mutex *lock)

/* doesn't lock */
int __vb2_fop_release(struct file *file)

would make sense ?

(I hope we end that thread soon :))

--
Regards,
Sylwester
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diff mbox

Patch

diff --git a/drivers/media/platform/exynos4-is/fimc-capture.c b/drivers/media/platform/exynos4-is/fimc-capture.c
index fb27ff7..3035e3b 100644
--- a/drivers/media/platform/exynos4-is/fimc-capture.c
+++ b/drivers/media/platform/exynos4-is/fimc-capture.c
@@ -549,7 +549,7 @@  static int fimc_capture_release(struct file *file)
 		vc->streaming = false;
 	}
 
-	ret = vb2_fop_release(file);
+	ret = vb2_fop_release_unlock(file);
 
 	if (close) {
 		clear_bit(ST_CAPT_BUSY, &fimc->state);
diff --git a/drivers/media/platform/exynos4-is/fimc-lite.c b/drivers/media/platform/exynos4-is/fimc-lite.c
index e5798f7..dc87429 100644
--- a/drivers/media/platform/exynos4-is/fimc-lite.c
+++ b/drivers/media/platform/exynos4-is/fimc-lite.c
@@ -546,7 +546,7 @@  static int fimc_lite_release(struct file *file)
 		mutex_unlock(&entity->parent->graph_mutex);
 	}
 
-	vb2_fop_release(file);
+	vb2_fop_release_unlock(file);
 	pm_runtime_put(&fimc->pdev->dev);
 	clear_bit(ST_FLITE_SUSPENDED, &fimc->state);
 
diff --git a/drivers/media/v4l2-core/videobuf2-core.c b/drivers/media/v4l2-core/videobuf2-core.c
index 594c75e..2716714 100644
--- a/drivers/media/v4l2-core/videobuf2-core.c
+++ b/drivers/media/v4l2-core/videobuf2-core.c
@@ -2619,18 +2619,36 @@  int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma)
 }
 EXPORT_SYMBOL_GPL(vb2_fop_mmap);
 
-int vb2_fop_release(struct file *file)
+static int _vb2_fop_release(struct file *file, struct mutex *lock)
 {
 	struct video_device *vdev = video_devdata(file);
 
 	if (file->private_data == vdev->queue->owner) {
+		if (lock)
+			mutex_lock(lock);
 		vb2_queue_release(vdev->queue);
 		vdev->queue->owner = NULL;
+		if (lock)
+			mutex_unlock(lock);
 	}
 	return v4l2_fh_release(file);
 }
+
+int vb2_fop_release(struct file *file)
+{
+	struct video_device *vdev = video_devdata(file);
+	struct mutex *lock = vdev->queue->lock ? vdev->queue->lock : vdev->lock;
+
+	return _vb2_fop_release(file, lock);
+}
 EXPORT_SYMBOL_GPL(vb2_fop_release);
 
+int vb2_fop_release_unlock(struct file *file)
+{
+	return _vb2_fop_release(file, NULL);
+}
+EXPORT_SYMBOL_GPL(vb2_fop_release_unlock);
+
 ssize_t vb2_fop_write(struct file *file, char __user *buf,
 		size_t count, loff_t *ppos)
 {
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 6781258..6fcb603 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -491,6 +491,7 @@  int vb2_ioctl_expbuf(struct file *file, void *priv,
 
 int vb2_fop_mmap(struct file *file, struct vm_area_struct *vma);
 int vb2_fop_release(struct file *file);
+int vb2_fop_release_unlock(struct file *file);
 ssize_t vb2_fop_write(struct file *file, char __user *buf,
 		size_t count, loff_t *ppos);
 ssize_t vb2_fop_read(struct file *file, char __user *buf,