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

[Thomas Hellström]

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.grodzov...@amd.com>
Cc: Christian König <christian.koe...@amd.com>
Cc: Christian Koenig <christian.koe...@amd.com>
Cc: Huang Rui <ray.hu...@amd.com>
Cc: dri-devel@lists.freedesktop.org
Cc: <sta...@vger.kernel.org> # v5.15+
Signed-off-by: Thomas Hellström <thomas.hellst...@linux.intel.com>
---
  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