From 03c0c5f6641533f5fc14bf4e76d2304197402552 Mon Sep 17 00:00:00 2001
From: Andres Rodriguez <andresx7@gmail.com>
Date: Wed, 26 Apr 2017 10:46:20 -0400
Subject: [PATCH] dma-buf: avoid scheduling on fence status query v2
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Git-commit: 03c0c5f6641533f5fc14bf4e76d2304197402552
Patch-mainline: v4.13-rc1
References: bsc#794563
When a timeout of zero is specified, the caller is only interested in
the fence status.
In the current implementation, dma_fence_default_wait will always call
schedule_timeout() at least once for an unsignaled fence. This adds a
significant overhead to a fence status query.
Avoid this overhead by returning early if a zero timeout is specified.
V2: move early return after enable_signaling
Signed-off-by: Andres Rodriguez <andresx7@gmail.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170426144620.3560-1-andresx7@gmail.com
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/dma-buf/dma-fence.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 0918d3f003d6..57da14c15987 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -402,6 +402,11 @@ dma_fence_default_wait(struct dma_fence *fence, bool intr, signed long timeout)
}
}
+ if (!timeout) {
+ ret = 0;
+ goto out;
+ }
+
cb.base.func = dma_fence_default_wait_cb;
cb.task = current;
list_add(&cb.base.node, &fence->cb_list);
--
2.20.1