Re: [PATCH] dma-buf: fence debugging

Christian König
2017-03-31T12:15:40Z

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@arm.linux.org.uk>

Reviewed-by: Christian König <christian.koenig@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;
>