[PATCH] dma-buf: fence debugging

[Christian König]

Am 31.03.2017 um 12:00 schrieb Russell King:
> Add debugfs output to report shared and exclusive fences on a dma_buf
> object.  This produces output such as:
>
> Dma-buf Objects:
> size    flags   mode    count   exp_name
> 08294400        00000000        00000005        00000005        drm
>          Exclusive fence: etnaviv 134000.gpu signalled
>          Attached Devices:
>          gpu-subsystem
> Total 1 devices attached
>
>
> Total 1 objects, 8294400 bytes
>
>
> Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>

Reviewed-by: Christian König <christian.koenig at amd.com>

> ---
>   drivers/dma-buf/dma-buf.c | 34 +++++++++++++++++++++++++++++++++-
>   1 file changed, 33 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 0007b792827b..f72aaacbe023 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -1059,7 +1059,11 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
>   	int ret;
>   	struct dma_buf *buf_obj;
>   	struct dma_buf_attachment *attach_obj;
> -	int count = 0, attach_count;
> +	struct reservation_object *robj;
> +	struct reservation_object_list *fobj;
> +	struct dma_fence *fence;
> +	unsigned seq;
> +	int count = 0, attach_count, shared_count, i;
>   	size_t size = 0;
>   
>   	ret = mutex_lock_interruptible(&db_list.lock);
> @@ -1085,6 +1090,34 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
>   				file_count(buf_obj->file),
>   				buf_obj->exp_name);
>   
> +		robj = buf_obj->resv;
> +		while (true) {
> +			seq = read_seqcount_begin(&robj->seq);
> +			rcu_read_lock();
> +			fobj = rcu_dereference(robj->fence);
> +			shared_count = fobj ? fobj->shared_count : 0;
> +			fence = rcu_dereference(robj->fence_excl);
> +			if (!read_seqcount_retry(&robj->seq, seq))
> +				break;
> +			rcu_read_unlock();
> +		}
> +
> +		if (fence)
> +			seq_printf(s, "\tExclusive fence: %s %s %ssignalled\n",
> +				   fence->ops->get_driver_name(fence),
> +				   fence->ops->get_timeline_name(fence),
> +				   dma_fence_is_signaled(fence) ? "" : "un");
> +		for (i = 0; i < shared_count; i++) {
> +			fence = rcu_dereference(fobj->shared[i]);
> +			if (!dma_fence_get_rcu(fence))
> +				continue;
> +			seq_printf(s, "\tShared fence: %s %s %ssignalled\n",
> +				   fence->ops->get_driver_name(fence),
> +				   fence->ops->get_timeline_name(fence),
> +				   dma_fence_is_signaled(fence) ? "" : "un");
> +		}
> +		rcu_read_unlock();
> +
>   		seq_puts(s, "\tAttached Devices:\n");
>   		attach_count = 0;
>