xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

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

Browse Source 
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>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170516111042.24719-1-chris@chris-wilson.co.uk
This commit is contained in:
Chris Wilson
2017-05-16 12:10:42 +01:00
committed by Gustavo Padovan
parent c16f291dee
commit 71ebc9a379
3 changed files with 44 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

11
include/linux/sync_file.h
View File

@@ -23,7 +23,6 @@
/**
* struct sync_file - sync file to export to the userspace
* @file: file representing this fence
* @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 +30,14 @@
*/
struct sync_file {
struct file *file;
char name[32];
/**
* @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).
*/
char user_name[32];
#ifdef CONFIG_DEBUG_FS
struct list_head sync_file_list;
#endif
@@ -46,5 +52,6 @@ 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 */