From e24165537312723e2900831dd6e7415b8d85278c Mon Sep 17 00:00:00 2001 From: Gustavo Padovan Date: Fri, 5 Aug 2016 10:39:38 -0300 Subject: [PATCH] dma-buf/sync_file: only enable fence signalling on poll() Signalling doesn't need to be enabled at sync_file creation, it is only required if userspace waiting the fence to signal through poll(). Thus we delay fence_add_callback() until poll is called. It only adds the callback the first time poll() is called. This avoid re-adding the same callback multiple times. v2: rebase and update to work with new fence support for sync_file v3: use atomic operation to set enabled and protect fence_add_callback() v4: use user bit from fence flags (comment from Chris Wilson) v5: use ternary if on poll return (comment from Chris Wilson) Signed-off-by: Gustavo Padovan Reviewed-by: Chris Wilson Signed-off-by: Sumit Semwal [sumits: remove unused var status] Link: http://patchwork.freedesktop.org/patch/msgid/1470404378-27961-1-git-send-email-gustavo@padovan.org --- drivers/dma-buf/sync_file.c | 21 ++++++++------------- include/linux/sync_file.h | 2 ++ 2 files changed, 10 insertions(+), 13 deletions(-) diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c index 2873760e02a9..486d29c1a830 100644 --- a/drivers/dma-buf/sync_file.c +++ b/drivers/dma-buf/sync_file.c @@ -86,8 +86,6 @@ struct sync_file *sync_file_create(struct fence *fence) fence->ops->get_timeline_name(fence), fence->context, fence->seqno); - fence_add_callback(fence, &sync_file->cb, fence_check_cb_func); - return sync_file; } EXPORT_SYMBOL(sync_file_create); @@ -274,9 +272,6 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a, goto err; } - fence_add_callback(sync_file->fence, &sync_file->cb, - fence_check_cb_func); - strlcpy(sync_file->name, name, sizeof(sync_file->name)); return sync_file; @@ -291,7 +286,8 @@ static void sync_file_free(struct kref *kref) struct sync_file *sync_file = container_of(kref, struct sync_file, kref); - fence_remove_callback(sync_file->fence, &sync_file->cb); + if (test_bit(POLL_ENABLED, &sync_file->fence->flags)) + fence_remove_callback(sync_file->fence, &sync_file->cb); fence_put(sync_file->fence); kfree(sync_file); } @@ -307,17 +303,16 @@ static int sync_file_release(struct inode *inode, struct file *file) static unsigned int sync_file_poll(struct file *file, poll_table *wait) { struct sync_file *sync_file = file->private_data; - int status; poll_wait(file, &sync_file->wq, wait); - status = fence_is_signaled(sync_file->fence); + if (!test_and_set_bit(POLL_ENABLED, &sync_file->fence->flags)) { + if (fence_add_callback(sync_file->fence, &sync_file->cb, + fence_check_cb_func) < 0) + wake_up_all(&sync_file->wq); + } - if (status) - return POLLIN; - if (status < 0) - return POLLERR; - return 0; + return fence_is_signaled(sync_file->fence) ? POLLIN : 0; } static long sync_file_ioctl_merge(struct sync_file *sync_file, diff --git a/include/linux/sync_file.h b/include/linux/sync_file.h index f7de5a0b3d12..aa17ccfc2f57 100644 --- a/include/linux/sync_file.h +++ b/include/linux/sync_file.h @@ -45,6 +45,8 @@ struct sync_file { struct fence_cb cb; }; +#define POLL_ENABLED FENCE_FLAG_USER_BITS + struct sync_file *sync_file_create(struct fence *fence); struct fence *sync_file_get_fence(int fd); -- 2.20.1