From 71ebc9a3795818eab52e81bbcbdfae130ee35d9e Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Tue, 16 May 2017 12:10:42 +0100 Subject: dma-buf/sync-file: Defer creation of sync_file->name 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 Cc: Sumit Semwal Cc: Gustavo Padovan Cc: Daniel Vetter Cc: David Herrmann Reviewed-by: Daniel Vetter Signed-off-by: Gustavo Padovan Link: http://patchwork.freedesktop.org/patch/msgid/20170516111042.24719-1-chris@chris-wilson.co.uk --- include/linux/sync_file.h | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'include') diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h index d37beefdfbd5..5726107963b2 100644 --- a/include/linux/sync_file.h +++ b/include/linux/sync_file.h @@ -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 */ -- cgit v1.2.3