From: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
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 <gustavo.padovan@xxxxxxxxxxxxxxx>
Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
drivers/dma-buf/sync_file.c | 20 ++++++++------------
include/linux/sync_file.h | 2 ++
2 files changed, 10 insertions(+), 12 deletions(-)
diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
index 2873760..82b5334 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);
}
@@ -311,13 +307,13 @@ static unsigned int sync_file_poll(struct file *file, poll_table *wait)
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 f7de5a0..aa17ccf 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);
--
2.5.5
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