On Wed, Jun 02, 2021 at 04:03:58PM +0200, Christian König wrote:
> Drop the whole rcu handling since we are holding the resv lock anyway.
>
> v2: drop all rcu handling instead.
>
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> ---
> drivers/dma-buf/dma-buf.c | 27 +++++++++------------------
> 1 file changed, 9 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index eadd1eaa2fb5..ee04fb442015 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -1349,15 +1349,14 @@ EXPORT_SYMBOL_GPL(dma_buf_vunmap);
> #ifdef CONFIG_DEBUG_FS
> 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;
> struct dma_resv *robj;
> struct dma_resv_list *fobj;
> struct dma_fence *fence;
> - unsigned seq;
> int count = 0, attach_count, shared_count, i;
> size_t size = 0;
> + int ret;
>
> ret = mutex_lock_interruptible(&db_list.lock);
>
> @@ -1383,33 +1382,25 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused)
> buf_obj->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();
> - }
> -
> + fence = rcu_dereference_protected(robj->fence_excl,
> + dma_resv_held(robj));
> 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");
> +
> + fobj = rcu_dereference_protected(robj->fence,
> + dma_resv_held(robj));
> + shared_count = fobj ? fobj->shared_count : 0;
> for (i = 0; i < shared_count; i++) {
> - fence = rcu_dereference(fobj->shared[i]);
> - if (!dma_fence_get_rcu(fence))
> - continue;
> + fence = rcu_dereference_protected(fobj->shared[i],
> + dma_resv_held(robj));
> 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");
> - dma_fence_put(fence);
> }
> - rcu_read_unlock();
>
> seq_puts(s, "\tAttached Devices:\n");
> attach_count = 0;
> --
> 2.25.1
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
