Re: [Intel-gfx] [PATCH 3/4] drm/ttm: Don't leak a resource on eviction error

Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx> · Thu, 22 Jun 2023 16:08:32 +0200

On 6/22/23 15:55, Andi Shyti wrote:
Hi Thomas,

On Thu, Jun 22, 2023 at 12:14:11PM +0200, Thomas Hellström wrote:
On eviction errors other than -EMULTIHOP we were leaking a resource.
Fix.

Fixes: 403797925768 ("drm/ttm: Fix multihop assert on eviction.")
Cc: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Christian Koenig <christian.koenig@xxxxxxx>
Cc: Huang Rui <ray.huang@xxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: <stable@xxxxxxxxxxxxxxx> # v5.15+
Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
---
  drivers/gpu/drm/ttm/ttm_bo.c | 16 ++++++++--------
  1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 615d30c4262d..89530f2a027f 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -462,14 +462,14 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo,
  	ret = ttm_bo_handle_move_mem(bo, evict_mem, true, ctx, &hop);
  	if (ret == -EMULTIHOP) {
  		ret = ttm_bo_bounce_temp_buffer(bo, &evict_mem, ctx, &hop);
-		if (ret) {
-			if (ret != -ERESTARTSYS && ret != -EINTR)
-				pr_err("Buffer eviction failed\n");
-			ttm_resource_free(bo, &evict_mem);
-			goto out;
-		}
-		/* try and move to final place now. */
-		goto bounce;
+		if (!ret)
+			/* try and move to final place now. */
+			goto bounce;
As we are at this, can't we replace this with a while()? Goto's
used instead of a while loop are a fist in the eye...

I'm completely OK with that. this patch already did away with one of 
them. Let's hear Christian's opinion first, though.

Thanks,

Thomas






It looks even better:

	while (1) {
		ret = ttm_bo_handle_move_mem(bo, evict_mem, true, ctx, &hop);
		if (!ret)
			break;

		if (ret == -EMULTIHOP)
			ret = ttm_bo_bounce_temp_buffer(bo, &evict_mem,
							ctx, &hop);

		/* try again */
		if (!ret)
			continue;

		ttm_resource_free(bo, &evict_mem);
		if (ret != -ERESTARTSYS && ret != -EINTR)
			pr_err("Buffer eviction failed\n");

		break;
	}

Andi

+	}
+	if (ret) {
+		ttm_resource_free(bo, &evict_mem);
+		if (ret != -ERESTARTSYS && ret != -EINTR)
+			pr_err("Buffer eviction failed\n");
  	}
  out:
  	return ret;
--
2.40.1






