[PATCH] dma-buf/sync-file: Defer creation of sync_file->name

[PATCH] dma-buf/sync-file: Defer creation of sync_file->name

[Chris Wilson]

Constructing the name takes the majority of the time for allocating a
sync_file to wrap a fence, and the name is very rarely used (only via
the sync_file status user interface). To reduce the impact on the common
path (that of creating sync_file to pass around), defer the construction
of the name until it is first used.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
---
 drivers/dma-buf/sync_file.c | 18 +++++++++++-------
 include/linux/sync_file.h   |  2 +-
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
index 2321035f6204..2cccfa834778 100644
--- a/drivers/dma-buf/sync_file.c
+++ b/drivers/dma-buf/sync_file.c
@@ -82,11 +82,6 @@ struct sync_file *sync_file_create(struct dma_fence *fence)
 
 	sync_file->fence = dma_fence_get(fence);
 
-	snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",
-		 fence->ops->get_driver_name(fence),
-		 fence->ops->get_timeline_name(fence), fence->context,
-		 fence->seqno);
-
 	return sync_file;
 }
 EXPORT_SYMBOL(sync_file_create);
@@ -268,7 +263,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
 		goto err;
 	}
 
-	strlcpy(sync_file->name, name, sizeof(sync_file->name));
+	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
 	return sync_file;
 
 err:
@@ -422,7 +417,16 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
 	}
 
 no_fences:
-	strlcpy(info.name, sync_file->name, sizeof(info.name));
+	if (!sync_file->user_name[0]) {
+		scnprintf(sync_file->user_name,
+			  sizeof(sync_file->user_name),
+			  "%s-%s%llu-%d",
+			  sync_file->fence->ops->get_driver_name(sync_file->fence),
+			  sync_file->fence->ops->get_timeline_name(sync_file->fence),
+			  sync_file->fence->context,
+			  sync_file->fence->seqno);
+	}
+	strlcpy(info.name, sync_file->user_name, sizeof(info.name));
 	info.status = dma_fence_is_signaled(sync_file->fence);
 	info.num_fences = num_fences;
 
diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
index 3e3ab84fc4cd..0cbeff29f510 100644
--- a/include/linux/sync_file.h
+++ b/include/linux/sync_file.h
@@ -34,7 +34,7 @@
 struct sync_file {
 	struct file		*file;
 	struct kref		kref;
-	char			name[32];
+	char			user_name[32];
 #ifdef CONFIG_DEBUG_FS
 	struct list_head	sync_file_list;
 #endif
-- 
2.11.0

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Re: [PATCH] dma-buf/sync-file: Defer creation of sync_file->name

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 11141 bytes --]

Hi Chris,

[auto build test WARNING on linus/master]
[also build test WARNING on v4.11 next-20170512]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Chris-Wilson/dma-buf-sync-file-Defer-creation-of-sync_file-name/20170512-193751
reproduce: make htmldocs

All warnings (new ones prefixed by >>):

   WARNING: convert(1) not found, for SVG to PDF conversion install ImageMagick (https://www.imagemagick.org)
   arch/x86/include/asm/uaccess_32.h:1: warning: no structured comments found
   include/linux/init.h:1: warning: no structured comments found
   include/linux/mod_devicetable.h:686: warning: Excess struct/union/enum/typedef member 'ver_major' description in 'fsl_mc_device_id'
   include/linux/mod_devicetable.h:686: warning: Excess struct/union/enum/typedef member 'ver_minor' description in 'fsl_mc_device_id'
   kernel/sched/core.c:2088: warning: No description found for parameter 'rf'
   kernel/sched/core.c:2088: warning: Excess function parameter 'cookie' description in 'try_to_wake_up_local'
   include/linux/kthread.h:26: warning: Excess function parameter '...' description in 'kthread_create'
   kernel/sys.c:1: warning: no structured comments found
   include/linux/device.h:969: warning: No description found for parameter 'dma_ops'
   drivers/dma-buf/seqno-fence.c:1: warning: no structured comments found
>> include/linux/sync_file.h:47: warning: No description found for parameter 'user_name'
>> include/linux/sync_file.h:47: warning: Excess struct/union/enum/typedef member 'name' description in 'sync_file'
   include/linux/iio/iio.h:597: warning: No description found for parameter 'trig_readonly'
   include/linux/iio/trigger.h:151: warning: No description found for parameter 'indio_dev'
   include/linux/iio/trigger.h:151: warning: No description found for parameter 'trig'
   include/linux/device.h:970: warning: No description found for parameter 'dma_ops'
   include/linux/usb/gadget.h:230: warning: No description found for parameter 'claimed'
   include/linux/usb/gadget.h:230: warning: No description found for parameter 'enabled'
   include/linux/usb/gadget.h:408: warning: No description found for parameter 'quirk_altset_not_supp'
   include/linux/usb/gadget.h:408: warning: No description found for parameter 'quirk_stall_not_supp'
   include/linux/usb/gadget.h:408: warning: No description found for parameter 'quirk_zlp_not_supp'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'set_busid'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'irq_handler'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'irq_preinstall'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'irq_postinstall'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'irq_uninstall'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'debugfs_init'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'gem_open_object'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'gem_close_object'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'prime_handle_to_fd'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'prime_fd_to_handle'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'gem_prime_export'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'gem_prime_import'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'gem_prime_pin'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'gem_prime_unpin'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'gem_prime_res_obj'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'gem_prime_get_sg_table'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'gem_prime_import_sg_table'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'gem_prime_vmap'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'gem_prime_vunmap'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'gem_prime_mmap'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'gem_vm_ops'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'major'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'minor'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'patchlevel'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'name'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'desc'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'date'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'driver_features'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'ioctls'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'num_ioctls'
   include/drm/drm_drv.h:524: warning: No description found for parameter 'fops'
   include/drm/drm_color_mgmt.h:1: warning: no structured comments found
   drivers/gpu/drm/drm_plane_helper.c:403: warning: No description found for parameter 'ctx'
   drivers/gpu/drm/drm_plane_helper.c:404: warning: No description found for parameter 'ctx'
   drivers/gpu/drm/i915/intel_lpe_audio.c:350: warning: No description found for parameter 'dp_output'
   drivers/gpu/drm/i915/intel_lpe_audio.c:350: warning: No description found for parameter 'link_rate'
   drivers/gpu/drm/i915/intel_lpe_audio.c:351: warning: No description found for parameter 'dp_output'
   drivers/gpu/drm/i915/intel_lpe_audio.c:351: warning: No description found for parameter 'link_rate'
   Documentation/core-api/assoc_array.rst:13: WARNING: Enumerated list ends without a blank line; unexpected unindent.
   Documentation/doc-guide/sphinx.rst:126: ERROR: Unknown target name: "sphinx c domain".
   kernel/sched/fair.c:7650: WARNING: Inline emphasis start-string without end-string.
   kernel/time/timer.c:1200: ERROR: Unexpected indentation.
   kernel/time/timer.c:1202: ERROR: Unexpected indentation.
   kernel/time/timer.c:1203: WARNING: Block quote ends without a blank line; unexpected unindent.
   include/linux/wait.h:122: WARNING: Block quote ends without a blank line; unexpected unindent.
   include/linux/wait.h:125: ERROR: Unexpected indentation.
   include/linux/wait.h:127: WARNING: Block quote ends without a blank line; unexpected unindent.
   kernel/time/hrtimer.c:990: WARNING: Block quote ends without a blank line; unexpected unindent.
   kernel/signal.c:322: WARNING: Inline literal start-string without end-string.
   include/linux/iio/iio.h:219: ERROR: Unexpected indentation.
   include/linux/iio/iio.h:220: WARNING: Block quote ends without a blank line; unexpected unindent.
   include/linux/iio/iio.h:226: WARNING: Definition list ends without a blank line; unexpected unindent.
   drivers/iio/industrialio-core.c:638: ERROR: Unknown target name: "iio_val".
   drivers/iio/industrialio-core.c:645: ERROR: Unknown target name: "iio_val".
   drivers/message/fusion/mptbase.c:5051: WARNING: Definition list ends without a blank line; unexpected unindent.
   drivers/tty/serial/serial_core.c:1898: WARNING: Definition list ends without a blank line; unexpected unindent.
   drivers/pci/pci.c:3456: ERROR: Unexpected indentation.
   include/linux/regulator/driver.h:271: ERROR: Unknown target name: "regulator_regmap_x_voltage".
   include/linux/spi/spi.h:370: ERROR: Unexpected indentation.
   drivers/gpu/drm/drm_scdc_helper.c:203: ERROR: Unexpected indentation.
   drivers/gpu/drm/drm_scdc_helper.c:204: WARNING: Block quote ends without a blank line; unexpected unindent.
   drivers/gpu/drm/drm_ioctl.c:690: WARNING: Definition list ends without a blank line; unexpected unindent.
   Documentation/gpu/todo.rst:111: ERROR: Unknown target name: "drm_fb".
   sound/soc/soc-core.c:2670: ERROR: Unknown target name: "snd_soc_daifmt".
   sound/core/jack.c:312: ERROR: Unknown target name: "snd_jack_btn".
   Documentation/usb/typec.rst:116: ERROR: Error in "kernel-doc" directive:
   invalid option block.

vim +/user_name +47 include/linux/sync_file.h

a02b9dc90 include/linux/sync_file.h           Gustavo Padovan 2016-08-05  31   * @fence:		fence with the fences in the sync_file
a02b9dc90 include/linux/sync_file.h           Gustavo Padovan 2016-08-05  32   * @cb:			fence callback information
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28  33   */
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28  34  struct sync_file {
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28  35  	struct file		*file;
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28  36  	struct kref		kref;
184ed11f9 include/linux/sync_file.h           Chris Wilson    2017-05-12  37  	char			user_name[32];
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28  38  #ifdef CONFIG_DEBUG_FS
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28  39  	struct list_head	sync_file_list;
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28  40  #endif
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28  41  
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28  42  	wait_queue_head_t	wq;
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28  43  
f54d18670 include/linux/sync_file.h           Chris Wilson    2016-10-25  44  	struct dma_fence	*fence;
f54d18670 include/linux/sync_file.h           Chris Wilson    2016-10-25  45  	struct dma_fence_cb cb;
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28  46  };
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28 @47  
f54d18670 include/linux/sync_file.h           Chris Wilson    2016-10-25  48  #define POLL_ENABLED DMA_FENCE_FLAG_USER_BITS
e24165537 include/linux/sync_file.h           Gustavo Padovan 2016-08-05  49  
f54d18670 include/linux/sync_file.h           Chris Wilson    2016-10-25  50  struct sync_file *sync_file_create(struct dma_fence *fence);
f54d18670 include/linux/sync_file.h           Chris Wilson    2016-10-25  51  struct dma_fence *sync_file_get_fence(int fd);
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28  52  
d4cab38e1 drivers/staging/android/sync_file.h Gustavo Padovan 2016-04-28  53  #endif /* _LINUX_SYNC_H */

:::::: The code at line 47 was first introduced by commit
:::::: d4cab38e153d62ecd502645390c0289c1b8337df staging/android: prepare sync_file for de-staging

:::::: TO: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
:::::: CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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Re: [PATCH] dma-buf/sync-file: Defer creation of sync_file->name

[Gustavo Padovan]

Hi Chris,

Thanks for the patch!

2017-05-12 Chris Wilson <chris@chris-wilson.co.uk>:

> Constructing the name takes the majority of the time for allocating a
> sync_file to wrap a fence, and the name is very rarely used (only via
> the sync_file status user interface). To reduce the impact on the common
> path (that of creating sync_file to pass around), defer the construction
> of the name until it is first used.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: Gustavo Padovan <gustavo@padovan.org>
> ---
>  drivers/dma-buf/sync_file.c | 18 +++++++++++-------
>  include/linux/sync_file.h   |  2 +-
>  2 files changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> index 2321035f6204..2cccfa834778 100644
> --- a/drivers/dma-buf/sync_file.c
> +++ b/drivers/dma-buf/sync_file.c
> @@ -82,11 +82,6 @@ struct sync_file *sync_file_create(struct dma_fence *fence)
>  
>  	sync_file->fence = dma_fence_get(fence);
>  
> -	snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",
> -		 fence->ops->get_driver_name(fence),
> -		 fence->ops->get_timeline_name(fence), fence->context,
> -		 fence->seqno);
> -
>  	return sync_file;
>  }
>  EXPORT_SYMBOL(sync_file_create);
> @@ -268,7 +263,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
>  		goto err;
>  	}
>  
> -	strlcpy(sync_file->name, name, sizeof(sync_file->name));
> +	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
>  	return sync_file;
>  
>  err:
> @@ -422,7 +417,16 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
>  	}
>  
>  no_fences:
> -	strlcpy(info.name, sync_file->name, sizeof(info.name));
> +	if (!sync_file->user_name[0]) {
> +		scnprintf(sync_file->user_name,
> +			  sizeof(sync_file->user_name),
> +			  "%s-%s%llu-%d",
> +			  sync_file->fence->ops->get_driver_name(sync_file->fence),
> +			  sync_file->fence->ops->get_timeline_name(sync_file->fence),
> +			  sync_file->fence->context,
> +			  sync_file->fence->seqno);
> +	}
> +	strlcpy(info.name, sync_file->user_name, sizeof(info.name));
>  	info.status = dma_fence_is_signaled(sync_file->fence);
>  	info.num_fences = num_fences;
>  
> diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
> index 3e3ab84fc4cd..0cbeff29f510 100644
> --- a/include/linux/sync_file.h
> +++ b/include/linux/sync_file.h
> @@ -34,7 +34,7 @@
>  struct sync_file {
>  	struct file		*file;
>  	struct kref		kref;
> -	char			name[32];
> +	char			user_name[32];

Looks good to me, but please re-spin it fixing the issue reported by the
test bot then I can apply it.

Gustavo

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[PATCH v3] dma-buf/sync-file: Defer creation of sync_file->name

[Chris Wilson]

Constructing the name takes the majority of the time for allocating a
sync_file to wrap a fence, and the name is very rarely used (only via
the sync_file status user interface). To reduce the impact on the common
path (that of creating sync_file to pass around), defer the construction
of the name until it is first used.

v2: Update kerneldoc (kbuild test robot)
v3: sync_debug.c was peeking at the name

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
---
 drivers/dma-buf/sync_debug.c |  3 ++-
 drivers/dma-buf/sync_file.c  | 34 +++++++++++++++++++++++++++-------
 include/linux/sync_file.h    |  5 +++--
 3 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c
index 4b1731ee7458..9a93f1085c63 100644
--- a/drivers/dma-buf/sync_debug.c
+++ b/drivers/dma-buf/sync_debug.c
@@ -134,7 +134,8 @@ static void sync_print_sync_file(struct seq_file *s,
 {
 	int i;
 
-	seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
+	seq_printf(s, "[%p] %s: %s\n", sync_file,
+		   sync_file_get_name(sync_file),
 		   sync_status_str(dma_fence_get_status(sync_file->fence)));
 
 	if (dma_fence_is_array(sync_file->fence)) {
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
index c9eb4997cfcc..d105079ec45c 100644
--- a/drivers/dma-buf/sync_file.c
+++ b/drivers/dma-buf/sync_file.c
@@ -80,11 +80,6 @@ struct sync_file *sync_file_create(struct dma_fence *fence)
 
 	sync_file->fence = dma_fence_get(fence);
 
-	snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",
-		 fence->ops->get_driver_name(fence),
-		 fence->ops->get_timeline_name(fence), fence->context,
-		 fence->seqno);
-
 	return sync_file;
 }
 EXPORT_SYMBOL(sync_file_create);
@@ -129,6 +124,31 @@ struct dma_fence *sync_file_get_fence(int fd)
 }
 EXPORT_SYMBOL(sync_file_get_fence);
 
+/**
+ * sync_file_get_name - get the name of the sync_file
+ * @sync_file:		sync_file to get the fence from
+ *
+ * Each sync_file may have a name assigned either by the user (when merging
+ * sync_files together) or created from the fence it contains. However,
+ * construction of the name is deferred until first use.
+ *
+ * Returns: a string representing the name
+ */
+char *sync_file_get_name(struct sync_file *sync_file)
+{
+	if (!sync_file->user_name[0]) {
+		scnprintf(sync_file->user_name,
+			  sizeof(sync_file->user_name),
+			  "%s-%s%llu-%d",
+			  sync_file->fence->ops->get_driver_name(sync_file->fence),
+			  sync_file->fence->ops->get_timeline_name(sync_file->fence),
+			  sync_file->fence->context,
+			  sync_file->fence->seqno);
+	}
+
+	return sync_file->user_name;
+}
+
 static int sync_file_set_fence(struct sync_file *sync_file,
 			       struct dma_fence **fences, int num_fences)
 {
@@ -266,7 +286,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
 		goto err;
 	}
 
-	strlcpy(sync_file->name, name, sizeof(sync_file->name));
+	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
 	return sync_file;
 
 err:
@@ -419,7 +439,7 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
 	}
 
 no_fences:
-	strlcpy(info.name, sync_file->name, sizeof(info.name));
+	strlcpy(info.name, sync_file_get_name(sync_file), sizeof(info.name));
 	info.status = dma_fence_is_signaled(sync_file->fence);
 	info.num_fences = num_fences;
 
diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
index d37beefdfbd5..0f3f05325c84 100644
--- a/include/linux/sync_file.h
+++ b/include/linux/sync_file.h
@@ -23,7 +23,7 @@
 /**
  * struct sync_file - sync file to export to the userspace
  * @file:		file representing this fence
- * @name:		name of sync_file.  Useful for debugging
+ * @user_name:		name of sync_file.  Useful for debugging
  * @sync_file_list:	membership in global file list
  * @wq:			wait queue for fence signaling
  * @fence:		fence with the fences in the sync_file
@@ -31,7 +31,7 @@
  */
 struct sync_file {
 	struct file		*file;
-	char			name[32];
+	char			user_name[32];
 #ifdef CONFIG_DEBUG_FS
 	struct list_head	sync_file_list;
 #endif
@@ -46,5 +46,6 @@ struct sync_file {
 
 struct sync_file *sync_file_create(struct dma_fence *fence);
 struct dma_fence *sync_file_get_fence(int fd);
+char *sync_file_get_name(struct sync_file *sync_file);
 
 #endif /* _LINUX_SYNC_H */
-- 
2.11.0

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Re: [PATCH v3] dma-buf/sync-file: Defer creation of sync_file->name

[Daniel Vetter]

On Fri, May 12, 2017 at 07:55:42PM +0100, Chris Wilson wrote:
> Constructing the name takes the majority of the time for allocating a
> sync_file to wrap a fence, and the name is very rarely used (only via
> the sync_file status user interface). To reduce the impact on the common
> path (that of creating sync_file to pass around), defer the construction
> of the name until it is first used.
> 
> v2: Update kerneldoc (kbuild test robot)
> v3: sync_debug.c was peeking at the name
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: Gustavo Padovan <gustavo@padovan.org>
> ---
>  drivers/dma-buf/sync_debug.c |  3 ++-
>  drivers/dma-buf/sync_file.c  | 34 +++++++++++++++++++++++++++-------
>  include/linux/sync_file.h    |  5 +++--
>  3 files changed, 32 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c
> index 4b1731ee7458..9a93f1085c63 100644
> --- a/drivers/dma-buf/sync_debug.c
> +++ b/drivers/dma-buf/sync_debug.c
> @@ -134,7 +134,8 @@ static void sync_print_sync_file(struct seq_file *s,
>  {
>  	int i;
>  
> -	seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
> +	seq_printf(s, "[%p] %s: %s\n", sync_file,
> +		   sync_file_get_name(sync_file),
>  		   sync_status_str(dma_fence_get_status(sync_file->fence)));
>  
>  	if (dma_fence_is_array(sync_file->fence)) {
> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> index c9eb4997cfcc..d105079ec45c 100644
> --- a/drivers/dma-buf/sync_file.c
> +++ b/drivers/dma-buf/sync_file.c
> @@ -80,11 +80,6 @@ struct sync_file *sync_file_create(struct dma_fence *fence)
>  
>  	sync_file->fence = dma_fence_get(fence);
>  
> -	snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",
> -		 fence->ops->get_driver_name(fence),
> -		 fence->ops->get_timeline_name(fence), fence->context,
> -		 fence->seqno);
> -
>  	return sync_file;
>  }
>  EXPORT_SYMBOL(sync_file_create);
> @@ -129,6 +124,31 @@ struct dma_fence *sync_file_get_fence(int fd)
>  }
>  EXPORT_SYMBOL(sync_file_get_fence);
>  
> +/**
> + * sync_file_get_name - get the name of the sync_file
> + * @sync_file:		sync_file to get the fence from
> + *
> + * Each sync_file may have a name assigned either by the user (when merging
> + * sync_files together) or created from the fence it contains. However,
> + * construction of the name is deferred until first use.
> + *
> + * Returns: a string representing the name
> + */
> +char *sync_file_get_name(struct sync_file *sync_file)
> +{
> +	if (!sync_file->user_name[0]) {
> +		scnprintf(sync_file->user_name,
> +			  sizeof(sync_file->user_name),
> +			  "%s-%s%llu-%d",
> +			  sync_file->fence->ops->get_driver_name(sync_file->fence),
> +			  sync_file->fence->ops->get_timeline_name(sync_file->fence),
> +			  sync_file->fence->context,
> +			  sync_file->fence->seqno);
> +	}

This is mildly race. Do we care? Deserves at least a comment that we don't
care, with that ack: me.
-Daniel

> +
> +	return sync_file->user_name;
> +}
> +
>  static int sync_file_set_fence(struct sync_file *sync_file,
>  			       struct dma_fence **fences, int num_fences)
>  {
> @@ -266,7 +286,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
>  		goto err;
>  	}
>  
> -	strlcpy(sync_file->name, name, sizeof(sync_file->name));
> +	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
>  	return sync_file;
>  
>  err:
> @@ -419,7 +439,7 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
>  	}
>  
>  no_fences:
> -	strlcpy(info.name, sync_file->name, sizeof(info.name));
> +	strlcpy(info.name, sync_file_get_name(sync_file), sizeof(info.name));
>  	info.status = dma_fence_is_signaled(sync_file->fence);
>  	info.num_fences = num_fences;
>  
> diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
> index d37beefdfbd5..0f3f05325c84 100644
> --- a/include/linux/sync_file.h
> +++ b/include/linux/sync_file.h
> @@ -23,7 +23,7 @@
>  /**
>   * struct sync_file - sync file to export to the userspace
>   * @file:		file representing this fence
> - * @name:		name of sync_file.  Useful for debugging
> + * @user_name:		name of sync_file.  Useful for debugging
>   * @sync_file_list:	membership in global file list
>   * @wq:			wait queue for fence signaling
>   * @fence:		fence with the fences in the sync_file
> @@ -31,7 +31,7 @@
>   */
>  struct sync_file {
>  	struct file		*file;
> -	char			name[32];
> +	char			user_name[32];
>  #ifdef CONFIG_DEBUG_FS
>  	struct list_head	sync_file_list;
>  #endif
> @@ -46,5 +46,6 @@ struct sync_file {
>  
>  struct sync_file *sync_file_create(struct dma_fence *fence);
>  struct dma_fence *sync_file_get_fence(int fd);
> +char *sync_file_get_name(struct sync_file *sync_file);
>  
>  #endif /* _LINUX_SYNC_H */
> -- 
> 2.11.0
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [Intel-gfx] [PATCH v3] dma-buf/sync-file: Defer creation of sync_file->name

[Chris Wilson]

On Mon, May 15, 2017 at 09:01:29AM +0200, Daniel Vetter wrote:
> On Fri, May 12, 2017 at 07:55:42PM +0100, Chris Wilson wrote:
> > Constructing the name takes the majority of the time for allocating a
> > sync_file to wrap a fence, and the name is very rarely used (only via
> > the sync_file status user interface). To reduce the impact on the common
> > path (that of creating sync_file to pass around), defer the construction
> > of the name until it is first used.
> > 
> > v2: Update kerneldoc (kbuild test robot)
> > v3: sync_debug.c was peeking at the name
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Sumit Semwal <sumit.semwal@linaro.org>
> > Cc: Gustavo Padovan <gustavo@padovan.org>
> > ---
> >  drivers/dma-buf/sync_debug.c |  3 ++-
> >  drivers/dma-buf/sync_file.c  | 34 +++++++++++++++++++++++++++-------
> >  include/linux/sync_file.h    |  5 +++--
> >  3 files changed, 32 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c
> > index 4b1731ee7458..9a93f1085c63 100644
> > --- a/drivers/dma-buf/sync_debug.c
> > +++ b/drivers/dma-buf/sync_debug.c
> > @@ -134,7 +134,8 @@ static void sync_print_sync_file(struct seq_file *s,
> >  {
> >  	int i;
> >  
> > -	seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
> > +	seq_printf(s, "[%p] %s: %s\n", sync_file,
> > +		   sync_file_get_name(sync_file),
> >  		   sync_status_str(dma_fence_get_status(sync_file->fence)));
> >  
> >  	if (dma_fence_is_array(sync_file->fence)) {
> > diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> > index c9eb4997cfcc..d105079ec45c 100644
> > --- a/drivers/dma-buf/sync_file.c
> > +++ b/drivers/dma-buf/sync_file.c
> > @@ -80,11 +80,6 @@ struct sync_file *sync_file_create(struct dma_fence *fence)
> >  
> >  	sync_file->fence = dma_fence_get(fence);
> >  
> > -	snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",
> > -		 fence->ops->get_driver_name(fence),
> > -		 fence->ops->get_timeline_name(fence), fence->context,
> > -		 fence->seqno);
> > -
> >  	return sync_file;
> >  }
> >  EXPORT_SYMBOL(sync_file_create);
> > @@ -129,6 +124,31 @@ struct dma_fence *sync_file_get_fence(int fd)
> >  }
> >  EXPORT_SYMBOL(sync_file_get_fence);
> >  
> > +/**
> > + * sync_file_get_name - get the name of the sync_file
> > + * @sync_file:		sync_file to get the fence from
> > + *
> > + * Each sync_file may have a name assigned either by the user (when merging
> > + * sync_files together) or created from the fence it contains. However,
> > + * construction of the name is deferred until first use.
> > + *
> > + * Returns: a string representing the name
> > + */
> > +char *sync_file_get_name(struct sync_file *sync_file)
> > +{
> > +	if (!sync_file->user_name[0]) {
> > +		scnprintf(sync_file->user_name,
> > +			  sizeof(sync_file->user_name),
> > +			  "%s-%s%llu-%d",
> > +			  sync_file->fence->ops->get_driver_name(sync_file->fence),
> > +			  sync_file->fence->ops->get_timeline_name(sync_file->fence),
> > +			  sync_file->fence->context,
> > +			  sync_file->fence->seqno);
> > +	}
> 
> This is mildly race. Do we care? Deserves at least a comment that we don't
> care, with that ack: me.

Hopefully, we don't care. It's not even a given that the fence->ops
return the same names at different times. The only sore point is that
this is an ioctl, so not the usual debugfs handwave.

We can cut down the race somewhat

if (!name[0]) {
	char buf[sizeof(sync_file->user_name)];
	struct dma_fence *fence;
	int len;

	rcu_read_lock();
	fence = sync_file->fence;
	len = scnprintf(buf, sizeof(buf), "%s-%s%llu-%d",
			fence->ops->get_driver_name(sync_file->fence),
			fence->ops->get_timeline_name(sync_file->fence),
			fence->context,
			fence->seqno);
	rcu_read_unlock();

	spin_lock(&global_sync_file_name_lock);
	if (!sync_file->user_name[0])
		memcpy(sync_file->user_name[0], buf, len + 1);
	spin_unlock(&global_sync_file_name_lock);
}

Even doing the staging to a local before doing a memcpy will be enough
to trim the race to a few cycles -- and leave it under the
rcu_read_unlock to keep preempt disabled.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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[PATCH v4] dma-buf/sync-file: Defer creation of sync_file->name

[Chris Wilson]

Constructing the name takes the majority of the time for allocating a
sync_file to wrap a fence, and the name is very rarely used (only via
the sync_file status user interface). To reduce the impact on the common
path (that of creating sync_file to pass around), defer the construction
of the name until it is first used.

v2: Update kerneldoc (kbuild test robot)
v3: sync_debug.c was peeking at the name
v4: Comment upon the potential race between two users of
sync_file_get_name() and claim that such a race is below the level of
notice. However, to prevent any future nuisance, use a global spinlock
to serialize the assignment of the name.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
---
 drivers/dma-buf/sync_debug.c |  3 ++-
 drivers/dma-buf/sync_file.c  | 54 ++++++++++++++++++++++++++++++++++++++------
 include/linux/sync_file.h    |  5 ++--
 3 files changed, 52 insertions(+), 10 deletions(-)

diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c
index 4b1731ee7458..9a93f1085c63 100644
--- a/drivers/dma-buf/sync_debug.c
+++ b/drivers/dma-buf/sync_debug.c
@@ -134,7 +134,8 @@ static void sync_print_sync_file(struct seq_file *s,
 {
 	int i;
 
-	seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
+	seq_printf(s, "[%p] %s: %s\n", sync_file,
+		   sync_file_get_name(sync_file),
 		   sync_status_str(dma_fence_get_status(sync_file->fence)));
 
 	if (dma_fence_is_array(sync_file->fence)) {
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
index c9eb4997cfcc..0d54de79ba76 100644
--- a/drivers/dma-buf/sync_file.c
+++ b/drivers/dma-buf/sync_file.c
@@ -80,11 +80,6 @@ struct sync_file *sync_file_create(struct dma_fence *fence)
 
 	sync_file->fence = dma_fence_get(fence);
 
-	snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",
-		 fence->ops->get_driver_name(fence),
-		 fence->ops->get_timeline_name(fence), fence->context,
-		 fence->seqno);
-
 	return sync_file;
 }
 EXPORT_SYMBOL(sync_file_create);
@@ -129,6 +124,51 @@ struct dma_fence *sync_file_get_fence(int fd)
 }
 EXPORT_SYMBOL(sync_file_get_fence);
 
+/**
+ * sync_file_get_name - get the name of the sync_file
+ * @sync_file:		sync_file to get the fence from
+ *
+ * Each sync_file may have a name assigned either by the user (when merging
+ * sync_files together) or created from the fence it contains. However,
+ * construction of the name is deferred until first use.
+ *
+ * Returns: a string representing the name
+ */
+char *sync_file_get_name(struct sync_file *sync_file)
+{
+	static DEFINE_SPINLOCK(name_lock);
+
+	if (!sync_file->user_name[0]) {
+		char buf[sizeof(sync_file->user_name)];
+		struct dma_fence *fence;
+		int len;
+
+		rcu_read_lock();
+		fence = sync_file->fence;
+		len = scnprintf(buf, sizeof(buf), "%s-%s%llu-%d",
+				fence->ops->get_driver_name(sync_file->fence),
+				fence->ops->get_timeline_name(sync_file->fence),
+				fence->context,
+				fence->seqno);
+
+		/* This is mildly racy, so we stage the printf into a local
+		 * buffer and do the copy with preempt disabled to trim the
+		 * race down to a few cycles. To completely eliminate the
+		 * race, we do the final assignment underneath a global
+		 * spinlock. A global lock should be adequate here for this
+		 * rare path (called from the middle of a user sw_sync status
+		 * ioctl and from debugfs).
+		 */
+		spin_lock(&name_lock);
+		if (!sync_file->user_name[0])
+			memcpy(sync_file->user_name, buf, len + 1);
+		spin_unlock(&name_lock);
+		rcu_read_unlock();
+	}
+
+	return sync_file->user_name;
+}
+
 static int sync_file_set_fence(struct sync_file *sync_file,
 			       struct dma_fence **fences, int num_fences)
 {
@@ -266,7 +306,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
 		goto err;
 	}
 
-	strlcpy(sync_file->name, name, sizeof(sync_file->name));
+	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
 	return sync_file;
 
 err:
@@ -419,7 +459,7 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
 	}
 
 no_fences:
-	strlcpy(info.name, sync_file->name, sizeof(info.name));
+	strlcpy(info.name, sync_file_get_name(sync_file), sizeof(info.name));
 	info.status = dma_fence_is_signaled(sync_file->fence);
 	info.num_fences = num_fences;
 
diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
index d37beefdfbd5..0f3f05325c84 100644
--- a/include/linux/sync_file.h
+++ b/include/linux/sync_file.h
@@ -23,7 +23,7 @@
 /**
  * struct sync_file - sync file to export to the userspace
  * @file:		file representing this fence
- * @name:		name of sync_file.  Useful for debugging
+ * @user_name:		name of sync_file.  Useful for debugging
  * @sync_file_list:	membership in global file list
  * @wq:			wait queue for fence signaling
  * @fence:		fence with the fences in the sync_file
@@ -31,7 +31,7 @@
  */
 struct sync_file {
 	struct file		*file;
-	char			name[32];
+	char			user_name[32];
 #ifdef CONFIG_DEBUG_FS
 	struct list_head	sync_file_list;
 #endif
@@ -46,5 +46,6 @@ struct sync_file {
 
 struct sync_file *sync_file_create(struct dma_fence *fence);
 struct dma_fence *sync_file_get_fence(int fd);
+char *sync_file_get_name(struct sync_file *sync_file);
 
 #endif /* _LINUX_SYNC_H */
-- 
2.11.0

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Re: [PATCH v4] dma-buf/sync-file: Defer creation of sync_file->name

[David Herrmann]

Hey

On Mon, May 15, 2017 at 12:10 PM, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> Constructing the name takes the majority of the time for allocating a
> sync_file to wrap a fence, and the name is very rarely used (only via
> the sync_file status user interface). To reduce the impact on the common
> path (that of creating sync_file to pass around), defer the construction
> of the name until it is first used.
>
> v2: Update kerneldoc (kbuild test robot)
> v3: sync_debug.c was peeking at the name
> v4: Comment upon the potential race between two users of
> sync_file_get_name() and claim that such a race is below the level of
> notice. However, to prevent any future nuisance, use a global spinlock
> to serialize the assignment of the name.
>
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: Gustavo Padovan <gustavo@padovan.org>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/dma-buf/sync_debug.c |  3 ++-
>  drivers/dma-buf/sync_file.c  | 54 ++++++++++++++++++++++++++++++++++++++------
>  include/linux/sync_file.h    |  5 ++--
>  3 files changed, 52 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c
> index 4b1731ee7458..9a93f1085c63 100644
> --- a/drivers/dma-buf/sync_debug.c
> +++ b/drivers/dma-buf/sync_debug.c
> @@ -134,7 +134,8 @@ static void sync_print_sync_file(struct seq_file *s,
>  {
>         int i;
>
> -       seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
> +       seq_printf(s, "[%p] %s: %s\n", sync_file,
> +                  sync_file_get_name(sync_file),
>                    sync_status_str(dma_fence_get_status(sync_file->fence)));
>
>         if (dma_fence_is_array(sync_file->fence)) {
> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> index c9eb4997cfcc..0d54de79ba76 100644
> --- a/drivers/dma-buf/sync_file.c
> +++ b/drivers/dma-buf/sync_file.c
> @@ -80,11 +80,6 @@ struct sync_file *sync_file_create(struct dma_fence *fence)
>
>         sync_file->fence = dma_fence_get(fence);
>
> -       snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",
> -                fence->ops->get_driver_name(fence),
> -                fence->ops->get_timeline_name(fence), fence->context,
> -                fence->seqno);
> -
>         return sync_file;
>  }
>  EXPORT_SYMBOL(sync_file_create);
> @@ -129,6 +124,51 @@ struct dma_fence *sync_file_get_fence(int fd)
>  }
>  EXPORT_SYMBOL(sync_file_get_fence);
>
> +/**
> + * sync_file_get_name - get the name of the sync_file
> + * @sync_file:         sync_file to get the fence from
> + *
> + * Each sync_file may have a name assigned either by the user (when merging
> + * sync_files together) or created from the fence it contains. However,
> + * construction of the name is deferred until first use.
> + *
> + * Returns: a string representing the name
> + */
> +char *sync_file_get_name(struct sync_file *sync_file)
> +{
> +       static DEFINE_SPINLOCK(name_lock);
> +
> +       if (!sync_file->user_name[0]) {
> +               char buf[sizeof(sync_file->user_name)];
> +               struct dma_fence *fence;
> +               int len;
> +
> +               rcu_read_lock();
> +               fence = sync_file->fence;
> +               len = scnprintf(buf, sizeof(buf), "%s-%s%llu-%d",
> +                               fence->ops->get_driver_name(sync_file->fence),
> +                               fence->ops->get_timeline_name(sync_file->fence),
> +                               fence->context,
> +                               fence->seqno);
> +
> +               /* This is mildly racy, so we stage the printf into a local
> +                * buffer and do the copy with preempt disabled to trim the
> +                * race down to a few cycles. To completely eliminate the
> +                * race, we do the final assignment underneath a global
> +                * spinlock. A global lock should be adequate here for this
> +                * rare path (called from the middle of a user sw_sync status
> +                * ioctl and from debugfs).
> +                */
> +               spin_lock(&name_lock);
> +               if (!sync_file->user_name[0])
> +                       memcpy(sync_file->user_name, buf, len + 1);

A racing reader might get a truncated string here. Note that a racing
reader does not take the lock as soon as the first byte is visible.
Not sure what the name is used for, but with that code it is not
reliable.

Also, please zero-terminate the string... scnprintf() does not
guarantee that, if it follows posix.

> +               spin_unlock(&name_lock);
> +               rcu_read_unlock();
> +       }
> +
> +       return sync_file->user_name;
> +}
> +
>  static int sync_file_set_fence(struct sync_file *sync_file,
>                                struct dma_fence **fences, int num_fences)
>  {
> @@ -266,7 +306,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
>                 goto err;
>         }
>
> -       strlcpy(sync_file->name, name, sizeof(sync_file->name));
> +       strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
>         return sync_file;
>
>  err:
> @@ -419,7 +459,7 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
>         }
>
>  no_fences:
> -       strlcpy(info.name, sync_file->name, sizeof(info.name));
> +       strlcpy(info.name, sync_file_get_name(sync_file), sizeof(info.name));

Don't use strlcpy(). It requires your source to be 0-terminated. Which
is not the case for sync_file->user_name. Either make sure user_name
is 0-terminated, or use strcpy().

Thanks
David

>         info.status = dma_fence_is_signaled(sync_file->fence);
>         info.num_fences = num_fences;
>
> diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
> index d37beefdfbd5..0f3f05325c84 100644
> --- a/include/linux/sync_file.h
> +++ b/include/linux/sync_file.h
> @@ -23,7 +23,7 @@
>  /**
>   * struct sync_file - sync file to export to the userspace
>   * @file:              file representing this fence
> - * @name:              name of sync_file.  Useful for debugging
> + * @user_name:         name of sync_file.  Useful for debugging
>   * @sync_file_list:    membership in global file list
>   * @wq:                        wait queue for fence signaling
>   * @fence:             fence with the fences in the sync_file
> @@ -31,7 +31,7 @@
>   */
>  struct sync_file {
>         struct file             *file;
> -       char                    name[32];
> +       char                    user_name[32];
>  #ifdef CONFIG_DEBUG_FS
>         struct list_head        sync_file_list;
>  #endif
> @@ -46,5 +46,6 @@ struct sync_file {
>
>  struct sync_file *sync_file_create(struct dma_fence *fence);
>  struct dma_fence *sync_file_get_fence(int fd);
> +char *sync_file_get_name(struct sync_file *sync_file);
>
>  #endif /* _LINUX_SYNC_H */
> --
> 2.11.0
>
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> https://lists.freedesktop.org/mailman/listinfo/dri-devel
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Re: [PATCH v4] dma-buf/sync-file: Defer creation of sync_file->name

[Chris Wilson]

On Mon, May 15, 2017 at 12:50:04PM +0200, David Herrmann wrote:
> Hey
> 
> On Mon, May 15, 2017 at 12:10 PM, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> > Constructing the name takes the majority of the time for allocating a
> > sync_file to wrap a fence, and the name is very rarely used (only via
> > the sync_file status user interface). To reduce the impact on the common
> > path (that of creating sync_file to pass around), defer the construction
> > of the name until it is first used.
> >
> > v2: Update kerneldoc (kbuild test robot)
> > v3: sync_debug.c was peeking at the name
> > v4: Comment upon the potential race between two users of
> > sync_file_get_name() and claim that such a race is below the level of
> > notice. However, to prevent any future nuisance, use a global spinlock
> > to serialize the assignment of the name.
> >
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Sumit Semwal <sumit.semwal@linaro.org>
> > Cc: Gustavo Padovan <gustavo@padovan.org>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > ---
> >  drivers/dma-buf/sync_debug.c |  3 ++-
> >  drivers/dma-buf/sync_file.c  | 54 ++++++++++++++++++++++++++++++++++++++------
> >  include/linux/sync_file.h    |  5 ++--
> >  3 files changed, 52 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c
> > index 4b1731ee7458..9a93f1085c63 100644
> > --- a/drivers/dma-buf/sync_debug.c
> > +++ b/drivers/dma-buf/sync_debug.c
> > @@ -134,7 +134,8 @@ static void sync_print_sync_file(struct seq_file *s,
> >  {
> >         int i;
> >
> > -       seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
> > +       seq_printf(s, "[%p] %s: %s\n", sync_file,
> > +                  sync_file_get_name(sync_file),
> >                    sync_status_str(dma_fence_get_status(sync_file->fence)));
> >
> >         if (dma_fence_is_array(sync_file->fence)) {
> > diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> > index c9eb4997cfcc..0d54de79ba76 100644
> > --- a/drivers/dma-buf/sync_file.c
> > +++ b/drivers/dma-buf/sync_file.c
> > @@ -80,11 +80,6 @@ struct sync_file *sync_file_create(struct dma_fence *fence)
> >
> >         sync_file->fence = dma_fence_get(fence);
> >
> > -       snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",
> > -                fence->ops->get_driver_name(fence),
> > -                fence->ops->get_timeline_name(fence), fence->context,
> > -                fence->seqno);
> > -
> >         return sync_file;
> >  }
> >  EXPORT_SYMBOL(sync_file_create);
> > @@ -129,6 +124,51 @@ struct dma_fence *sync_file_get_fence(int fd)
> >  }
> >  EXPORT_SYMBOL(sync_file_get_fence);
> >
> > +/**
> > + * sync_file_get_name - get the name of the sync_file
> > + * @sync_file:         sync_file to get the fence from
> > + *
> > + * Each sync_file may have a name assigned either by the user (when merging
> > + * sync_files together) or created from the fence it contains. However,
> > + * construction of the name is deferred until first use.
> > + *
> > + * Returns: a string representing the name
> > + */
> > +char *sync_file_get_name(struct sync_file *sync_file)
> > +{
> > +       static DEFINE_SPINLOCK(name_lock);
> > +
> > +       if (!sync_file->user_name[0]) {
> > +               char buf[sizeof(sync_file->user_name)];
> > +               struct dma_fence *fence;
> > +               int len;
> > +
> > +               rcu_read_lock();
> > +               fence = sync_file->fence;
> > +               len = scnprintf(buf, sizeof(buf), "%s-%s%llu-%d",
> > +                               fence->ops->get_driver_name(sync_file->fence),
> > +                               fence->ops->get_timeline_name(sync_file->fence),
> > +                               fence->context,
> > +                               fence->seqno);
> > +
> > +               /* This is mildly racy, so we stage the printf into a local
> > +                * buffer and do the copy with preempt disabled to trim the
> > +                * race down to a few cycles. To completely eliminate the
> > +                * race, we do the final assignment underneath a global
> > +                * spinlock. A global lock should be adequate here for this
> > +                * rare path (called from the middle of a user sw_sync status
> > +                * ioctl and from debugfs).
> > +                */
> > +               spin_lock(&name_lock);
> > +               if (!sync_file->user_name[0])
> > +                       memcpy(sync_file->user_name, buf, len + 1);
> 
> A racing reader might get a truncated string here. Note that a racing
> reader does not take the lock as soon as the first byte is visible.
> Not sure what the name is used for, but with that code it is not
> reliable.

The comment does explain that the use case is purely debug. We may as
well forget the spinlock. It is always a valid string, if incomplete, and
the race is fairly immaterial. For the value of the name, I'd be quite
happy to ignore it entirely and have it only set when the user provides
one.
 
> Also, please zero-terminate the string... scnprintf() does not
> guarantee that, if it follows posix.

But the kernel vs[c]nprintf does ensure that the string is NUL-terminated.
-Chris

-- 
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Re: [PATCH v4] dma-buf/sync-file: Defer creation of sync_file->name

[David Herrmann]

Hey

On Mon, May 15, 2017 at 1:42 PM, Chris Wilson <chris@chris-wilson.co.uk> wrote:
> On Mon, May 15, 2017 at 12:50:04PM +0200, David Herrmann wrote:
>> Hey
>>
>> On Mon, May 15, 2017 at 12:10 PM, Chris Wilson <chris@chris-wilson.co.uk> wrote:
>> > Constructing the name takes the majority of the time for allocating a
>> > sync_file to wrap a fence, and the name is very rarely used (only via
>> > the sync_file status user interface). To reduce the impact on the common
>> > path (that of creating sync_file to pass around), defer the construction
>> > of the name until it is first used.
>> >
>> > v2: Update kerneldoc (kbuild test robot)
>> > v3: sync_debug.c was peeking at the name
>> > v4: Comment upon the potential race between two users of
>> > sync_file_get_name() and claim that such a race is below the level of
>> > notice. However, to prevent any future nuisance, use a global spinlock
>> > to serialize the assignment of the name.
>> >
>> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
>> > Cc: Sumit Semwal <sumit.semwal@linaro.org>
>> > Cc: Gustavo Padovan <gustavo@padovan.org>
>> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>> > ---
>> >  drivers/dma-buf/sync_debug.c |  3 ++-
>> >  drivers/dma-buf/sync_file.c  | 54 ++++++++++++++++++++++++++++++++++++++------
>> >  include/linux/sync_file.h    |  5 ++--
>> >  3 files changed, 52 insertions(+), 10 deletions(-)
>> >
>> > diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c
>> > index 4b1731ee7458..9a93f1085c63 100644
>> > --- a/drivers/dma-buf/sync_debug.c
>> > +++ b/drivers/dma-buf/sync_debug.c
>> > @@ -134,7 +134,8 @@ static void sync_print_sync_file(struct seq_file *s,
>> >  {
>> >         int i;
>> >
>> > -       seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
>> > +       seq_printf(s, "[%p] %s: %s\n", sync_file,
>> > +                  sync_file_get_name(sync_file),
>> >                    sync_status_str(dma_fence_get_status(sync_file->fence)));
>> >
>> >         if (dma_fence_is_array(sync_file->fence)) {
>> > diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
>> > index c9eb4997cfcc..0d54de79ba76 100644
>> > --- a/drivers/dma-buf/sync_file.c
>> > +++ b/drivers/dma-buf/sync_file.c
>> > @@ -80,11 +80,6 @@ struct sync_file *sync_file_create(struct dma_fence *fence)
>> >
>> >         sync_file->fence = dma_fence_get(fence);
>> >
>> > -       snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",
>> > -                fence->ops->get_driver_name(fence),
>> > -                fence->ops->get_timeline_name(fence), fence->context,
>> > -                fence->seqno);
>> > -
>> >         return sync_file;
>> >  }
>> >  EXPORT_SYMBOL(sync_file_create);
>> > @@ -129,6 +124,51 @@ struct dma_fence *sync_file_get_fence(int fd)
>> >  }
>> >  EXPORT_SYMBOL(sync_file_get_fence);
>> >
>> > +/**
>> > + * sync_file_get_name - get the name of the sync_file
>> > + * @sync_file:         sync_file to get the fence from
>> > + *
>> > + * Each sync_file may have a name assigned either by the user (when merging
>> > + * sync_files together) or created from the fence it contains. However,
>> > + * construction of the name is deferred until first use.
>> > + *
>> > + * Returns: a string representing the name
>> > + */
>> > +char *sync_file_get_name(struct sync_file *sync_file)
>> > +{
>> > +       static DEFINE_SPINLOCK(name_lock);
>> > +
>> > +       if (!sync_file->user_name[0]) {
>> > +               char buf[sizeof(sync_file->user_name)];
>> > +               struct dma_fence *fence;
>> > +               int len;
>> > +
>> > +               rcu_read_lock();
>> > +               fence = sync_file->fence;
>> > +               len = scnprintf(buf, sizeof(buf), "%s-%s%llu-%d",
>> > +                               fence->ops->get_driver_name(sync_file->fence),
>> > +                               fence->ops->get_timeline_name(sync_file->fence),
>> > +                               fence->context,
>> > +                               fence->seqno);
>> > +
>> > +               /* This is mildly racy, so we stage the printf into a local
>> > +                * buffer and do the copy with preempt disabled to trim the
>> > +                * race down to a few cycles. To completely eliminate the
>> > +                * race, we do the final assignment underneath a global
>> > +                * spinlock. A global lock should be adequate here for this
>> > +                * rare path (called from the middle of a user sw_sync status
>> > +                * ioctl and from debugfs).
>> > +                */
>> > +               spin_lock(&name_lock);
>> > +               if (!sync_file->user_name[0])
>> > +                       memcpy(sync_file->user_name, buf, len + 1);
>>
>> A racing reader might get a truncated string here. Note that a racing
>> reader does not take the lock as soon as the first byte is visible.
>> Not sure what the name is used for, but with that code it is not
>> reliable.
>
> The comment does explain that the use case is purely debug. We may as
> well forget the spinlock. It is always a valid string, if incomplete, and
> the race is fairly immaterial. For the value of the name, I'd be quite
> happy to ignore it entirely and have it only set when the user provides
> one.

The comment does not make it clear to me which part is protected here.
Whether it is just about racing writers, or whether it actually also
protects against racing readers. The lock gives the impression that it
protects only against racing writers, leaving open the issue with
racing readers. If that's not the case, I don't see the point of the
lock, given that racing writers would actually write the same string,
anyway.

>> Also, please zero-terminate the string... scnprintf() does not
>> guarantee that, if it follows posix.
>
> But the kernel vs[c]nprintf does ensure that the string is NUL-terminated.

You're right, the kernel does indeed differ from posix here. Sorry for
the noise.

Thanks
David
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[PATCH v5] dma-buf/sync-file: Defer creation of sync_file->name

[Chris Wilson]

Constructing the name takes the majority of the time for allocating a
sync_file to wrap a fence, and the name is very rarely used (only via
the sync_file status user interface). To reduce the impact on the common
path (that of creating sync_file to pass around), defer the construction
of the name until it is first used.

v2: Update kerneldoc (kbuild test robot)
v3: sync_debug.c was peeking at the name
v4: Comment upon the potential race between two users of
sync_file_get_name() and claim that such a race is below the level of
notice. However, to prevent any future nuisance, use a global spinlock
to serialize the assignment of the name.
v5: Completely avoid the read/write race by only storing the name passed
in from the user inside sync_file->user_name and passing in a buffer to
dynamically construct the name otherwise.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: David Herrmann <dh.herrmann@gmail.com>
---
 drivers/dma-buf/sync_debug.c |  4 +++-
 drivers/dma-buf/sync_file.c  | 39 ++++++++++++++++++++++++++++++++-------
 include/linux/sync_file.h    |  5 +++--
 3 files changed, 38 insertions(+), 10 deletions(-)

diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c
index 4b1731ee7458..59a3b2f8ee91 100644
--- a/drivers/dma-buf/sync_debug.c
+++ b/drivers/dma-buf/sync_debug.c
@@ -132,9 +132,11 @@ static void sync_print_obj(struct seq_file *s, struct sync_timeline *obj)
 static void sync_print_sync_file(struct seq_file *s,
 				  struct sync_file *sync_file)
 {
+	char buf[128];
 	int i;
 
-	seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
+	seq_printf(s, "[%p] %s: %s\n", sync_file,
+		   sync_file_get_name(sync_file, buf, sizeof(buf)),
 		   sync_status_str(dma_fence_get_status(sync_file->fence)));
 
 	if (dma_fence_is_array(sync_file->fence)) {
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
index c9eb4997cfcc..d7e219d2669d 100644
--- a/drivers/dma-buf/sync_file.c
+++ b/drivers/dma-buf/sync_file.c
@@ -80,11 +80,6 @@ struct sync_file *sync_file_create(struct dma_fence *fence)
 
 	sync_file->fence = dma_fence_get(fence);
 
-	snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",
-		 fence->ops->get_driver_name(fence),
-		 fence->ops->get_timeline_name(fence), fence->context,
-		 fence->seqno);
-
 	return sync_file;
 }
 EXPORT_SYMBOL(sync_file_create);
@@ -129,6 +124,36 @@ struct dma_fence *sync_file_get_fence(int fd)
 }
 EXPORT_SYMBOL(sync_file_get_fence);
 
+/**
+ * sync_file_get_name - get the name of the sync_file
+ * @sync_file:		sync_file to get the fence from
+ * @buf:		destination buffer to copy sync_file name into
+ * @len:		available size of destination buffer.
+ *
+ * Each sync_file may have a name assigned either by the user (when merging
+ * sync_files together) or created from the fence it contains. In the latter
+ * case construction of the name is deferred until use, and so requires
+ * sync_file_get_name().
+ *
+ * Returns: a string representing the name.
+ */
+char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
+{
+	if (sync_file->user_name[0]) {
+		strlcpy(buf, sync_file->user_name, len);
+	} else {
+		struct dma_fence *fence = sync_file->fence;
+
+		snprintf(buf, len, "%s-%s%llu-%d",
+			 fence->ops->get_driver_name(fence),
+			 fence->ops->get_timeline_name(fence),
+			 fence->context,
+			 fence->seqno);
+	}
+
+	return buf;
+}
+
 static int sync_file_set_fence(struct sync_file *sync_file,
 			       struct dma_fence **fences, int num_fences)
 {
@@ -266,7 +291,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
 		goto err;
 	}
 
-	strlcpy(sync_file->name, name, sizeof(sync_file->name));
+	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
 	return sync_file;
 
 err:
@@ -419,7 +444,7 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
 	}
 
 no_fences:
-	strlcpy(info.name, sync_file->name, sizeof(info.name));
+	sync_file_get_name(sync_file, info.name, sizeof(info.name));
 	info.status = dma_fence_is_signaled(sync_file->fence);
 	info.num_fences = num_fences;
 
diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
index d37beefdfbd5..5226d62ae91b 100644
--- a/include/linux/sync_file.h
+++ b/include/linux/sync_file.h
@@ -23,7 +23,7 @@
 /**
  * struct sync_file - sync file to export to the userspace
  * @file:		file representing this fence
- * @name:		name of sync_file.  Useful for debugging
+ * @user_name:		name of sync_file.  Useful for debugging
  * @sync_file_list:	membership in global file list
  * @wq:			wait queue for fence signaling
  * @fence:		fence with the fences in the sync_file
@@ -31,7 +31,7 @@
  */
 struct sync_file {
 	struct file		*file;
-	char			name[32];
+	char			user_name[32];
 #ifdef CONFIG_DEBUG_FS
 	struct list_head	sync_file_list;
 #endif
@@ -46,5 +46,6 @@ struct sync_file {
 
 struct sync_file *sync_file_create(struct dma_fence *fence);
 struct dma_fence *sync_file_get_fence(int fd);
+char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len);
 
 #endif /* _LINUX_SYNC_H */
-- 
2.11.0

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Re: [PATCH v5] dma-buf/sync-file: Defer creation of sync_file->name

[Chris Wilson]

On Tue, May 16, 2017 at 12:10:42PM +0100, Chris Wilson wrote:
> Constructing the name takes the majority of the time for allocating a
> sync_file to wrap a fence, and the name is very rarely used (only via
> the sync_file status user interface). To reduce the impact on the common
> path (that of creating sync_file to pass around), defer the construction
> of the name until it is first used.
> 
> v2: Update kerneldoc (kbuild test robot)
> v3: sync_debug.c was peeking at the name
> v4: Comment upon the potential race between two users of
> sync_file_get_name() and claim that such a race is below the level of
> notice. However, to prevent any future nuisance, use a global spinlock
> to serialize the assignment of the name.
> v5: Completely avoid the read/write race by only storing the name passed
> in from the user inside sync_file->user_name and passing in a buffer to
> dynamically construct the name otherwise.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: Gustavo Padovan <gustavo@padovan.org>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: David Herrmann <dh.herrmann@gmail.com>

Any thoughts on this one? It should completely avoid the race, with
the presumption that unless the user sets a name when merging the best
response is to show the fence name.

It may be interesting to actually show both; the encoded
sync_file->fence name and the user's identifier.
-Chris

> ---
>  drivers/dma-buf/sync_debug.c |  4 +++-
>  drivers/dma-buf/sync_file.c  | 39 ++++++++++++++++++++++++++++++++-------
>  include/linux/sync_file.h    |  5 +++--
>  3 files changed, 38 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c
> index 4b1731ee7458..59a3b2f8ee91 100644
> --- a/drivers/dma-buf/sync_debug.c
> +++ b/drivers/dma-buf/sync_debug.c
> @@ -132,9 +132,11 @@ static void sync_print_obj(struct seq_file *s, struct sync_timeline *obj)
>  static void sync_print_sync_file(struct seq_file *s,
>  				  struct sync_file *sync_file)
>  {
> +	char buf[128];
>  	int i;
>  
> -	seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
> +	seq_printf(s, "[%p] %s: %s\n", sync_file,
> +		   sync_file_get_name(sync_file, buf, sizeof(buf)),
>  		   sync_status_str(dma_fence_get_status(sync_file->fence)));
>  
>  	if (dma_fence_is_array(sync_file->fence)) {
> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> index c9eb4997cfcc..d7e219d2669d 100644
> --- a/drivers/dma-buf/sync_file.c
> +++ b/drivers/dma-buf/sync_file.c
> @@ -80,11 +80,6 @@ struct sync_file *sync_file_create(struct dma_fence *fence)
>  
>  	sync_file->fence = dma_fence_get(fence);
>  
> -	snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",
> -		 fence->ops->get_driver_name(fence),
> -		 fence->ops->get_timeline_name(fence), fence->context,
> -		 fence->seqno);
> -
>  	return sync_file;
>  }
>  EXPORT_SYMBOL(sync_file_create);
> @@ -129,6 +124,36 @@ struct dma_fence *sync_file_get_fence(int fd)
>  }
>  EXPORT_SYMBOL(sync_file_get_fence);
>  
> +/**
> + * sync_file_get_name - get the name of the sync_file
> + * @sync_file:		sync_file to get the fence from
> + * @buf:		destination buffer to copy sync_file name into
> + * @len:		available size of destination buffer.
> + *
> + * Each sync_file may have a name assigned either by the user (when merging
> + * sync_files together) or created from the fence it contains. In the latter
> + * case construction of the name is deferred until use, and so requires
> + * sync_file_get_name().
> + *
> + * Returns: a string representing the name.
> + */
> +char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
> +{
> +	if (sync_file->user_name[0]) {
> +		strlcpy(buf, sync_file->user_name, len);
> +	} else {
> +		struct dma_fence *fence = sync_file->fence;
> +
> +		snprintf(buf, len, "%s-%s%llu-%d",
> +			 fence->ops->get_driver_name(fence),
> +			 fence->ops->get_timeline_name(fence),
> +			 fence->context,
> +			 fence->seqno);
> +	}
> +
> +	return buf;
> +}
> +
>  static int sync_file_set_fence(struct sync_file *sync_file,
>  			       struct dma_fence **fences, int num_fences)
>  {
> @@ -266,7 +291,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
>  		goto err;
>  	}
>  
> -	strlcpy(sync_file->name, name, sizeof(sync_file->name));
> +	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
>  	return sync_file;
>  
>  err:
> @@ -419,7 +444,7 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
>  	}
>  
>  no_fences:
> -	strlcpy(info.name, sync_file->name, sizeof(info.name));
> +	sync_file_get_name(sync_file, info.name, sizeof(info.name));
>  	info.status = dma_fence_is_signaled(sync_file->fence);
>  	info.num_fences = num_fences;
>  
> diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
> index d37beefdfbd5..5226d62ae91b 100644
> --- a/include/linux/sync_file.h
> +++ b/include/linux/sync_file.h
> @@ -23,7 +23,7 @@
>  /**
>   * struct sync_file - sync file to export to the userspace
>   * @file:		file representing this fence
> - * @name:		name of sync_file.  Useful for debugging
> + * @user_name:		name of sync_file.  Useful for debugging
>   * @sync_file_list:	membership in global file list
>   * @wq:			wait queue for fence signaling
>   * @fence:		fence with the fences in the sync_file
> @@ -31,7 +31,7 @@
>   */
>  struct sync_file {
>  	struct file		*file;
> -	char			name[32];
> +	char			user_name[32];
>  #ifdef CONFIG_DEBUG_FS
>  	struct list_head	sync_file_list;
>  #endif
> @@ -46,5 +46,6 @@ struct sync_file {
>  
>  struct sync_file *sync_file_create(struct dma_fence *fence);
>  struct dma_fence *sync_file_get_fence(int fd);
> +char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len);
>  
>  #endif /* _LINUX_SYNC_H */
> -- 
> 2.11.0
> 

-- 
Chris Wilson, Intel Open Source Technology Centre
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Re: [PATCH v5] dma-buf/sync-file: Defer creation of sync_file->name

[Daniel Vetter]

On Tue, May 16, 2017 at 12:10:42PM +0100, Chris Wilson wrote:
> Constructing the name takes the majority of the time for allocating a
> sync_file to wrap a fence, and the name is very rarely used (only via
> the sync_file status user interface). To reduce the impact on the common
> path (that of creating sync_file to pass around), defer the construction
> of the name until it is first used.
> 
> v2: Update kerneldoc (kbuild test robot)
> v3: sync_debug.c was peeking at the name
> v4: Comment upon the potential race between two users of
> sync_file_get_name() and claim that such a race is below the level of
> notice. However, to prevent any future nuisance, use a global spinlock
> to serialize the assignment of the name.
> v5: Completely avoid the read/write race by only storing the name passed
> in from the user inside sync_file->user_name and passing in a buffer to
> dynamically construct the name otherwise.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: Gustavo Padovan <gustavo@padovan.org>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: David Herrmann <dh.herrmann@gmail.com>
> ---
>  drivers/dma-buf/sync_debug.c |  4 +++-
>  drivers/dma-buf/sync_file.c  | 39 ++++++++++++++++++++++++++++++++-------
>  include/linux/sync_file.h    |  5 +++--
>  3 files changed, 38 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c
> index 4b1731ee7458..59a3b2f8ee91 100644
> --- a/drivers/dma-buf/sync_debug.c
> +++ b/drivers/dma-buf/sync_debug.c
> @@ -132,9 +132,11 @@ static void sync_print_obj(struct seq_file *s, struct sync_timeline *obj)
>  static void sync_print_sync_file(struct seq_file *s,
>  				  struct sync_file *sync_file)
>  {
> +	char buf[128];
>  	int i;
>  
> -	seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
> +	seq_printf(s, "[%p] %s: %s\n", sync_file,
> +		   sync_file_get_name(sync_file, buf, sizeof(buf)),
>  		   sync_status_str(dma_fence_get_status(sync_file->fence)));
>  
>  	if (dma_fence_is_array(sync_file->fence)) {
> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> index c9eb4997cfcc..d7e219d2669d 100644
> --- a/drivers/dma-buf/sync_file.c
> +++ b/drivers/dma-buf/sync_file.c
> @@ -80,11 +80,6 @@ struct sync_file *sync_file_create(struct dma_fence *fence)
>  
>  	sync_file->fence = dma_fence_get(fence);
>  
> -	snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",
> -		 fence->ops->get_driver_name(fence),
> -		 fence->ops->get_timeline_name(fence), fence->context,
> -		 fence->seqno);
> -
>  	return sync_file;
>  }
>  EXPORT_SYMBOL(sync_file_create);
> @@ -129,6 +124,36 @@ struct dma_fence *sync_file_get_fence(int fd)
>  }
>  EXPORT_SYMBOL(sync_file_get_fence);
>  
> +/**
> + * sync_file_get_name - get the name of the sync_file
> + * @sync_file:		sync_file to get the fence from
> + * @buf:		destination buffer to copy sync_file name into
> + * @len:		available size of destination buffer.
> + *
> + * Each sync_file may have a name assigned either by the user (when merging
> + * sync_files together) or created from the fence it contains. In the latter
> + * case construction of the name is deferred until use, and so requires
> + * sync_file_get_name().
> + *
> + * Returns: a string representing the name.
> + */
> +char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
> +{
> +	if (sync_file->user_name[0]) {
> +		strlcpy(buf, sync_file->user_name, len);
> +	} else {
> +		struct dma_fence *fence = sync_file->fence;
> +
> +		snprintf(buf, len, "%s-%s%llu-%d",
> +			 fence->ops->get_driver_name(fence),
> +			 fence->ops->get_timeline_name(fence),
> +			 fence->context,
> +			 fence->seqno);
> +	}
> +
> +	return buf;
> +}
> +
>  static int sync_file_set_fence(struct sync_file *sync_file,
>  			       struct dma_fence **fences, int num_fences)
>  {
> @@ -266,7 +291,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
>  		goto err;
>  	}
>  
> -	strlcpy(sync_file->name, name, sizeof(sync_file->name));
> +	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
>  	return sync_file;
>  
>  err:
> @@ -419,7 +444,7 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
>  	}
>  
>  no_fences:
> -	strlcpy(info.name, sync_file->name, sizeof(info.name));
> +	sync_file_get_name(sync_file, info.name, sizeof(info.name));
>  	info.status = dma_fence_is_signaled(sync_file->fence);
>  	info.num_fences = num_fences;
>  
> diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
> index d37beefdfbd5..5226d62ae91b 100644
> --- a/include/linux/sync_file.h
> +++ b/include/linux/sync_file.h
> @@ -23,7 +23,7 @@
>  /**
>   * struct sync_file - sync file to export to the userspace
>   * @file:		file representing this fence
> - * @name:		name of sync_file.  Useful for debugging
> + * @user_name:		name of sync_file.  Useful for debugging
>   * @sync_file_list:	membership in global file list
>   * @wq:			wait queue for fence signaling
>   * @fence:		fence with the fences in the sync_file
> @@ -31,7 +31,7 @@
>   */
>  struct sync_file {
>  	struct file		*file;
> -	char			name[32];

Maybe inline kerneldoc an explain a bit better what's going on:

	/**
	 * @user_name:
	 *
	 * Name of the sync file provided by userspace, for merged fences.
	 * Otherwise generated through driver callbacks (in which case the
	 * entire array is 0).
	 */

Might be overkill, so not going to insist at all. Either way:

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Pls poke Gustavo or Sumits to also check it and pick it up.

Thanks, Daniel

> +	char			user_name[32];
>  #ifdef CONFIG_DEBUG_FS
>  	struct list_head	sync_file_list;
>  #endif
> @@ -46,5 +46,6 @@ struct sync_file {
>  
>  struct sync_file *sync_file_create(struct dma_fence *fence);
>  struct dma_fence *sync_file_get_fence(int fd);
> +char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len);
>  
>  #endif /* _LINUX_SYNC_H */
> -- 
> 2.11.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH v5] dma-buf/sync-file: Defer creation of sync_file->name

[Gustavo Padovan]

2017-05-22 Daniel Vetter <daniel@ffwll.ch>:

> On Tue, May 16, 2017 at 12:10:42PM +0100, Chris Wilson wrote:
> > Constructing the name takes the majority of the time for allocating a
> > sync_file to wrap a fence, and the name is very rarely used (only via
> > the sync_file status user interface). To reduce the impact on the common
> > path (that of creating sync_file to pass around), defer the construction
> > of the name until it is first used.
> > 
> > v2: Update kerneldoc (kbuild test robot)
> > v3: sync_debug.c was peeking at the name
> > v4: Comment upon the potential race between two users of
> > sync_file_get_name() and claim that such a race is below the level of
> > notice. However, to prevent any future nuisance, use a global spinlock
> > to serialize the assignment of the name.
> > v5: Completely avoid the read/write race by only storing the name passed
> > in from the user inside sync_file->user_name and passing in a buffer to
> > dynamically construct the name otherwise.
> > 
> > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> > Cc: Sumit Semwal <sumit.semwal@linaro.org>
> > Cc: Gustavo Padovan <gustavo@padovan.org>
> > Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> > Cc: David Herrmann <dh.herrmann@gmail.com>
> > ---
> >  drivers/dma-buf/sync_debug.c |  4 +++-
> >  drivers/dma-buf/sync_file.c  | 39 ++++++++++++++++++++++++++++++++-------
> >  include/linux/sync_file.h    |  5 +++--
> >  3 files changed, 38 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/dma-buf/sync_debug.c b/drivers/dma-buf/sync_debug.c
> > index 4b1731ee7458..59a3b2f8ee91 100644
> > --- a/drivers/dma-buf/sync_debug.c
> > +++ b/drivers/dma-buf/sync_debug.c
> > @@ -132,9 +132,11 @@ static void sync_print_obj(struct seq_file *s, struct sync_timeline *obj)
> >  static void sync_print_sync_file(struct seq_file *s,
> >  				  struct sync_file *sync_file)
> >  {
> > +	char buf[128];
> >  	int i;
> >  
> > -	seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
> > +	seq_printf(s, "[%p] %s: %s\n", sync_file,
> > +		   sync_file_get_name(sync_file, buf, sizeof(buf)),
> >  		   sync_status_str(dma_fence_get_status(sync_file->fence)));
> >  
> >  	if (dma_fence_is_array(sync_file->fence)) {
> > diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> > index c9eb4997cfcc..d7e219d2669d 100644
> > --- a/drivers/dma-buf/sync_file.c
> > +++ b/drivers/dma-buf/sync_file.c
> > @@ -80,11 +80,6 @@ struct sync_file *sync_file_create(struct dma_fence *fence)
> >  
> >  	sync_file->fence = dma_fence_get(fence);
> >  
> > -	snprintf(sync_file->name, sizeof(sync_file->name), "%s-%s%llu-%d",
> > -		 fence->ops->get_driver_name(fence),
> > -		 fence->ops->get_timeline_name(fence), fence->context,
> > -		 fence->seqno);
> > -
> >  	return sync_file;
> >  }
> >  EXPORT_SYMBOL(sync_file_create);
> > @@ -129,6 +124,36 @@ struct dma_fence *sync_file_get_fence(int fd)
> >  }
> >  EXPORT_SYMBOL(sync_file_get_fence);
> >  
> > +/**
> > + * sync_file_get_name - get the name of the sync_file
> > + * @sync_file:		sync_file to get the fence from
> > + * @buf:		destination buffer to copy sync_file name into
> > + * @len:		available size of destination buffer.
> > + *
> > + * Each sync_file may have a name assigned either by the user (when merging
> > + * sync_files together) or created from the fence it contains. In the latter
> > + * case construction of the name is deferred until use, and so requires
> > + * sync_file_get_name().
> > + *
> > + * Returns: a string representing the name.
> > + */
> > +char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len)
> > +{
> > +	if (sync_file->user_name[0]) {
> > +		strlcpy(buf, sync_file->user_name, len);
> > +	} else {
> > +		struct dma_fence *fence = sync_file->fence;
> > +
> > +		snprintf(buf, len, "%s-%s%llu-%d",
> > +			 fence->ops->get_driver_name(fence),
> > +			 fence->ops->get_timeline_name(fence),
> > +			 fence->context,
> > +			 fence->seqno);
> > +	}
> > +
> > +	return buf;
> > +}
> > +
> >  static int sync_file_set_fence(struct sync_file *sync_file,
> >  			       struct dma_fence **fences, int num_fences)
> >  {
> > @@ -266,7 +291,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
> >  		goto err;
> >  	}
> >  
> > -	strlcpy(sync_file->name, name, sizeof(sync_file->name));
> > +	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
> >  	return sync_file;
> >  
> >  err:
> > @@ -419,7 +444,7 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
> >  	}
> >  
> >  no_fences:
> > -	strlcpy(info.name, sync_file->name, sizeof(info.name));
> > +	sync_file_get_name(sync_file, info.name, sizeof(info.name));
> >  	info.status = dma_fence_is_signaled(sync_file->fence);
> >  	info.num_fences = num_fences;
> >  
> > diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h
> > index d37beefdfbd5..5226d62ae91b 100644
> > --- a/include/linux/sync_file.h
> > +++ b/include/linux/sync_file.h
> > @@ -23,7 +23,7 @@
> >  /**
> >   * struct sync_file - sync file to export to the userspace
> >   * @file:		file representing this fence
> > - * @name:		name of sync_file.  Useful for debugging
> > + * @user_name:		name of sync_file.  Useful for debugging
> >   * @sync_file_list:	membership in global file list
> >   * @wq:			wait queue for fence signaling
> >   * @fence:		fence with the fences in the sync_file
> > @@ -31,7 +31,7 @@
> >   */
> >  struct sync_file {
> >  	struct file		*file;
> > -	char			name[32];
> 
> Maybe inline kerneldoc an explain a bit better what's going on:
> 
> 	/**
> 	 * @user_name:
> 	 *
> 	 * Name of the sync file provided by userspace, for merged fences.
> 	 * Otherwise generated through driver callbacks (in which case the
> 	 * entire array is 0).
> 	 */
> 
> Might be overkill, so not going to insist at all. Either way:
> 
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

I fixed it. Applied with the modification proposed by Daniel. Thanks for
the patch.

Gustavo

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✓ Fi.CI.BAT: success for dma-buf/sync-file: Defer creation of sync_file->name (rev2)

[Patchwork]

== Series Details ==

Series: dma-buf/sync-file: Defer creation of sync_file->name (rev2)
URL   : https://patchwork.freedesktop.org/series/24353/
State : success

== Summary ==

Series 24353v2 dma-buf/sync-file: Defer creation of sync_file->name
https://patchwork.freedesktop.org/api/1.0/series/24353/revisions/2/mbox/

Test gem_exec_flush:
        Subgroup basic-batch-kernel-default-uc:
                pass       -> FAIL       (fi-snb-2600) fdo#100007

fdo#100007 https://bugs.freedesktop.org/show_bug.cgi?id=100007

fi-bdw-5557u     total:278  pass:267  dwarn:0   dfail:0   fail:0   skip:11  time:440s
fi-bdw-gvtdvm    total:278  pass:256  dwarn:8   dfail:0   fail:0   skip:14  time:436s
fi-bsw-n3050     total:278  pass:242  dwarn:0   dfail:0   fail:0   skip:36  time:579s
fi-bxt-j4205     total:278  pass:259  dwarn:0   dfail:0   fail:0   skip:19  time:514s
fi-byt-j1900     total:278  pass:254  dwarn:0   dfail:0   fail:0   skip:24  time:492s
fi-byt-n2820     total:278  pass:250  dwarn:0   dfail:0   fail:0   skip:28  time:489s
fi-hsw-4770      total:278  pass:262  dwarn:0   dfail:0   fail:0   skip:16  time:418s
fi-hsw-4770r     total:278  pass:262  dwarn:0   dfail:0   fail:0   skip:16  time:420s
fi-ilk-650       total:278  pass:228  dwarn:0   dfail:0   fail:0   skip:50  time:420s
fi-ivb-3520m     total:278  pass:260  dwarn:0   dfail:0   fail:0   skip:18  time:487s
fi-ivb-3770      total:278  pass:260  dwarn:0   dfail:0   fail:0   skip:18  time:468s
fi-kbl-7500u     total:278  pass:255  dwarn:5   dfail:0   fail:0   skip:18  time:462s
fi-kbl-7560u     total:278  pass:263  dwarn:5   dfail:0   fail:0   skip:10  time:569s
fi-skl-6260u     total:278  pass:268  dwarn:0   dfail:0   fail:0   skip:10  time:460s
fi-skl-6700hq    total:278  pass:261  dwarn:0   dfail:0   fail:0   skip:17  time:585s
fi-skl-6700k     total:278  pass:256  dwarn:4   dfail:0   fail:0   skip:18  time:469s
fi-skl-6770hq    total:278  pass:268  dwarn:0   dfail:0   fail:0   skip:10  time:504s
fi-skl-gvtdvm    total:278  pass:265  dwarn:0   dfail:0   fail:0   skip:13  time:441s
fi-snb-2520m     total:278  pass:250  dwarn:0   dfail:0   fail:0   skip:28  time:539s
fi-snb-2600      total:278  pass:248  dwarn:0   dfail:0   fail:1   skip:29  time:405s
fi-bxt-t5700 failed to collect. IGT log at Patchwork_4687/fi-bxt-t5700/igt.log

38d26beef9f31fa7ca983563cf86d4131defd94a drm-tip: 2017y-05m-12d-13h-15m-01s UTC integration manifest
f35f9bf dma-buf/sync-file: Defer creation of sync_file->name

== Logs ==

For more details see: https://intel-gfx-ci.01.org/CI/Patchwork_4687/
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✓ Fi.CI.BAT: success for dma-buf/sync-file: Defer creation of sync_file->name (rev3)

[Patchwork]

== Series Details ==

Series: dma-buf/sync-file: Defer creation of sync_file->name (rev3)
URL   : https://patchwork.freedesktop.org/series/24353/
State : success

== Summary ==

Series 24353v3 dma-buf/sync-file: Defer creation of sync_file->name
https://patchwork.freedesktop.org/api/1.0/series/24353/revisions/3/mbox/

Test gem_exec_flush:
        Subgroup basic-batch-kernel-default-uc:
                fail       -> PASS       (fi-snb-2600) fdo#100007
Test kms_busy:
        Subgroup basic-flip-default-c:
                incomplete -> PASS       (fi-bxt-j4205) fdo#101047

fdo#100007 https://bugs.freedesktop.org/show_bug.cgi?id=100007
fdo#101047 https://bugs.freedesktop.org/show_bug.cgi?id=101047

fi-bdw-gvtdvm    total:278  pass:256  dwarn:8   dfail:0   fail:0   skip:14  time:433s
fi-bxt-j4205     total:278  pass:259  dwarn:0   dfail:0   fail:0   skip:19  time:515s
fi-byt-j1900     total:278  pass:254  dwarn:0   dfail:0   fail:0   skip:24  time:495s
fi-byt-n2820     total:278  pass:250  dwarn:0   dfail:0   fail:0   skip:28  time:487s
fi-hsw-4770      total:278  pass:262  dwarn:0   dfail:0   fail:0   skip:16  time:418s
fi-ilk-650       total:278  pass:228  dwarn:0   dfail:0   fail:0   skip:50  time:419s
fi-ivb-3520m     total:278  pass:260  dwarn:0   dfail:0   fail:0   skip:18  time:502s
fi-kbl-7500u     total:278  pass:255  dwarn:5   dfail:0   fail:0   skip:18  time:462s
fi-kbl-7560u     total:278  pass:263  dwarn:5   dfail:0   fail:0   skip:10  time:572s
fi-skl-6700hq    total:278  pass:261  dwarn:0   dfail:0   fail:0   skip:17  time:577s
fi-skl-6700k     total:278  pass:256  dwarn:4   dfail:0   fail:0   skip:18  time:472s
fi-skl-6770hq    total:278  pass:268  dwarn:0   dfail:0   fail:0   skip:10  time:497s
fi-skl-gvtdvm    total:278  pass:265  dwarn:0   dfail:0   fail:0   skip:13  time:436s
fi-snb-2520m     total:278  pass:250  dwarn:0   dfail:0   fail:0   skip:28  time:531s
fi-snb-2600      total:278  pass:249  dwarn:0   dfail:0   fail:0   skip:29  time:404s
fi-bxt-t5700 failed to collect. IGT log at Patchwork_4694/fi-bxt-t5700/igt.log

d79d2bb351aa06bc5b39c070068fea112cfa29ef drm-tip: 2017y-05m-15d-08h-55m-10s UTC integration manifest
3ce68b0 dma-buf/sync-file: Defer creation of sync_file->name

== Logs ==

For more details see: https://intel-gfx-ci.01.org/CI/Patchwork_4694/
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Re: [PATCH] dma-buf/sync-file: Defer creation of sync_file->name

[kbuild test robot]

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Hi Chris,

[auto build test ERROR on linus/master]
[also build test ERROR on v4.12-rc1 next-20170516]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Chris-Wilson/dma-buf-sync-file-Defer-creation-of-sync_file-name/20170512-193751
config: x86_64-rhel (attached as .config)
compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   drivers//dma-buf/sync_debug.c: In function 'sync_print_sync_file':
>> drivers//dma-buf/sync_debug.c:137:53: error: 'struct sync_file' has no member named 'name'
     seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
                                                        ^~

vim +137 drivers//dma-buf/sync_debug.c

0f0d8406 drivers/staging/android/sync_debug.c Maarten Lankhorst 2014-07-01  131  
d7fdb0ae drivers/staging/android/sync_debug.c Gustavo Padovan   2016-01-21  132  static void sync_print_sync_file(struct seq_file *s,
d7fdb0ae drivers/staging/android/sync_debug.c Gustavo Padovan   2016-01-21  133  				  struct sync_file *sync_file)
0f0d8406 drivers/staging/android/sync_debug.c Maarten Lankhorst 2014-07-01  134  {
0f0d8406 drivers/staging/android/sync_debug.c Maarten Lankhorst 2014-07-01  135  	int i;
0f0d8406 drivers/staging/android/sync_debug.c Maarten Lankhorst 2014-07-01  136  
d7fdb0ae drivers/staging/android/sync_debug.c Gustavo Padovan   2016-01-21 @137  	seq_printf(s, "[%p] %s: %s\n", sync_file, sync_file->name,
d6c99f4b drivers/dma-buf/sync_debug.c         Chris Wilson      2017-01-04  138  		   sync_status_str(dma_fence_get_status(sync_file->fence)));
0f0d8406 drivers/staging/android/sync_debug.c Maarten Lankhorst 2014-07-01  139  
f54d1867 drivers/dma-buf/sync_debug.c         Chris Wilson      2016-10-25  140  	if (dma_fence_is_array(sync_file->fence)) {

:::::: The code at line 137 was first introduced by commit
:::::: d7fdb0ae9d115fa14ff3a5382c8a62de41c7786a staging/android: rename sync_fence to sync_file

:::::: TO: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
:::::: CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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✓ Fi.CI.BAT: success for dma-buf/sync-file: Defer creation of sync_file->name (rev4)

[Patchwork]

== Series Details ==

Series: dma-buf/sync-file: Defer creation of sync_file->name (rev4)
URL   : https://patchwork.freedesktop.org/series/24353/
State : success

== Summary ==

Series 24353v4 dma-buf/sync-file: Defer creation of sync_file->name
https://patchwork.freedesktop.org/api/1.0/series/24353/revisions/4/mbox/

Test gem_exec_flush:
        Subgroup basic-batch-kernel-default-uc:
                pass       -> FAIL       (fi-snb-2600) fdo#100007
Test kms_cursor_legacy:
        Subgroup basic-busy-flip-before-cursor-legacy:
                pass       -> FAIL       (fi-snb-2600) fdo#100215

fdo#100007 https://bugs.freedesktop.org/show_bug.cgi?id=100007
fdo#100215 https://bugs.freedesktop.org/show_bug.cgi?id=100215

fi-bdw-5557u     total:278  pass:267  dwarn:0   dfail:0   fail:0   skip:11  time:447s
fi-bdw-gvtdvm    total:278  pass:256  dwarn:8   dfail:0   fail:0   skip:14  time:431s
fi-bsw-n3050     total:278  pass:242  dwarn:0   dfail:0   fail:0   skip:36  time:582s
fi-bxt-j4205     total:278  pass:259  dwarn:0   dfail:0   fail:0   skip:19  time:512s
fi-byt-j1900     total:278  pass:254  dwarn:0   dfail:0   fail:0   skip:24  time:495s
fi-byt-n2820     total:278  pass:250  dwarn:0   dfail:0   fail:0   skip:28  time:493s
fi-hsw-4770      total:278  pass:262  dwarn:0   dfail:0   fail:0   skip:16  time:423s
fi-hsw-4770r     total:278  pass:262  dwarn:0   dfail:0   fail:0   skip:16  time:417s
fi-ilk-650       total:278  pass:228  dwarn:0   dfail:0   fail:0   skip:50  time:417s
fi-ivb-3520m     total:278  pass:260  dwarn:0   dfail:0   fail:0   skip:18  time:506s
fi-ivb-3770      total:278  pass:260  dwarn:0   dfail:0   fail:0   skip:18  time:472s
fi-kbl-7500u     total:278  pass:255  dwarn:5   dfail:0   fail:0   skip:18  time:467s
fi-kbl-7560u     total:278  pass:263  dwarn:5   dfail:0   fail:0   skip:10  time:579s
fi-skl-6260u     total:278  pass:268  dwarn:0   dfail:0   fail:0   skip:10  time:459s
fi-skl-6700hq    total:278  pass:261  dwarn:0   dfail:0   fail:0   skip:17  time:582s
fi-skl-6700k     total:278  pass:256  dwarn:4   dfail:0   fail:0   skip:18  time:466s
fi-skl-6770hq    total:278  pass:268  dwarn:0   dfail:0   fail:0   skip:10  time:500s
fi-skl-gvtdvm    total:278  pass:265  dwarn:0   dfail:0   fail:0   skip:13  time:442s
fi-snb-2520m     total:278  pass:250  dwarn:0   dfail:0   fail:0   skip:28  time:538s
fi-snb-2600      total:278  pass:247  dwarn:0   dfail:0   fail:2   skip:29  time:404s

fb5cb398a048f8e0fd9dab5686caba61961131be drm-tip: 2017y-05m-16d-11h-13m-20s UTC integration manifest
d559328 dma-buf/sync-file: Defer creation of sync_file->name

== Logs ==

For more details see: https://intel-gfx-ci.01.org/CI/Patchwork_4709/
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