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Commit f7974880 authored by John Einar Reitan's avatar John Einar Reitan Committed by Gustavo Padovan
Browse files

sync_file: Return consistent status in SYNC_IOC_FILE_INFO 



sync_file_ioctl_fence_info has a race between filling the status
of the underlying fences and the overall status of the sync_file.
If fence transitions in the time frame between its sync_fill_fence_info
and the later dma_fence_is_signaled for the sync_file, the returned
information is inconsistent showing non-signaled underlying fences but
an overall signaled state.

This patch changes sync_file_ioctl_fence_info to track what has been
encoded and using that as the overall sync_file status.

Tested-by: default avatarVamsidhar Reddy Gaddam <vamsidhar.gaddam@arm.com>
Signed-off-by: default avatarJohn Einar Reitan <john.reitan@arm.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarGustavo Padovan <gustavo.padovan@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171009134936.27219-1-john.reitan@arm.com
parent 78279127

drivers/dma-buf/sync_file.c

+12 −5
Original line number Diff line number Diff line
@@ -383,7 +383,7 @@ static long sync_file_ioctl_merge(struct sync_file *sync_file, 
	return err;

}



static void sync_fill_fence_info(struct dma_fence *fence,

static int sync_fill_fence_info(struct dma_fence *fence,

				 struct sync_fence_info *info)

{

	strlcpy(info->obj_name, fence->ops->get_timeline_name(fence),
@@ -399,6 +399,8 @@ static void sync_fill_fence_info(struct dma_fence *fence, 
		test_bit(DMA_FENCE_FLAG_TIMESTAMP_BIT, &fence->flags) ?

		ktime_to_ns(fence->timestamp) :

		ktime_set(0, 0);



	return info->status;

}



static long sync_file_ioctl_fence_info(struct sync_file *sync_file,
@@ -424,8 +426,12 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file, 
	 * sync_fence_info and return the actual number of fences on

	 * info->num_fences.

	 */

	if (!info.num_fences)

	if (!info.num_fences) {

		info.status = dma_fence_is_signaled(sync_file->fence);

		goto no_fences;

	} else {

		info.status = 1;

	}



	if (info.num_fences < num_fences)

		return -EINVAL;
@@ -435,8 +441,10 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file, 
	if (!fence_info)

		return -ENOMEM;



	for (i = 0; i < num_fences; i++)

		sync_fill_fence_info(fences[i], &fence_info[i]);

	for (i = 0; i < num_fences; i++) {

		int status = sync_fill_fence_info(fences[i], &fence_info[i]);

		info.status = info.status <= 0 ? info.status : status;

	}



	if (copy_to_user(u64_to_user_ptr(info.sync_fence_info), fence_info,

			 size)) {
@@ -446,7 +454,6 @@ static long sync_file_ioctl_fence_info(struct sync_file *sync_file, 


no_fences:

	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;



	if (copy_to_user((void __user *)arg, &info, sizeof(info)))