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71ebc9a379
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
57 lines
1.5 KiB
C
57 lines
1.5 KiB
C
/*
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* include/linux/sync_file.h
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*
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* Copyright (C) 2012 Google, Inc.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#ifndef _LINUX_SYNC_FILE_H
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#define _LINUX_SYNC_FILE_H
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#include <linux/types.h>
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#include <linux/ktime.h>
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#include <linux/list.h>
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#include <linux/spinlock.h>
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#include <linux/dma-fence.h>
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#include <linux/dma-fence-array.h>
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/**
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* struct sync_file - sync file to export to the userspace
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* @file: file representing this fence
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* @sync_file_list: membership in global file list
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* @wq: wait queue for fence signaling
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* @fence: fence with the fences in the sync_file
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* @cb: fence callback information
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*/
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struct sync_file {
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struct file *file;
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/**
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* @user_name:
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*
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* Name of the sync file provided by userspace, for merged fences.
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* Otherwise generated through driver callbacks (in which case the
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* entire array is 0).
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*/
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char user_name[32];
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#ifdef CONFIG_DEBUG_FS
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struct list_head sync_file_list;
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#endif
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wait_queue_head_t wq;
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struct dma_fence *fence;
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struct dma_fence_cb cb;
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};
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#define POLL_ENABLED DMA_FENCE_FLAG_USER_BITS
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struct sync_file *sync_file_create(struct dma_fence *fence);
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struct dma_fence *sync_file_get_fence(int fd);
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char *sync_file_get_name(struct sync_file *sync_file, char *buf, int len);
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#endif /* _LINUX_SYNC_H */
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