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 --- drivers/dma-buf/sync_file.c | 39 ++++++++++++++++++++++++++++++++------- 1 file changed, 32 insertions(+), 7 deletions(-) (limited to 'drivers/dma-buf/sync_file.c') diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c index dc89b1d484e8..545e2c5c4815 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: @@ -413,7 +438,7 @@ 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; -- cgit