Mesa (staging/22.0): winsys/amdgpu: fix a mutex deadlock when we fail to create pipe_screen

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Module: Mesa
Branch: staging/22.0
Commit: 6ed6a28fc75d4ffade7e7bbd8a4e52c0f5abaefc
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=6ed6a28fc75d4ffade7e7bbd8a4e52c0f5abaefc

Author: Marek Olšák <marek.olsak at amd.com>
Date:   Fri Apr 22 14:16:52 2022 -0400

winsys/amdgpu: fix a mutex deadlock when we fail to create pipe_screen

Fixes: 2eb067db0fe - winsys/amdgpu: add a new winsys for the new kernel driver

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer at amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16112>
(cherry picked from commit 4a982aa5421780a90b812e7654d4d32459d9bdbd)

---

 .pick_status.json                             |  2 +-
 src/gallium/winsys/amdgpu/drm/amdgpu_winsys.c | 15 +++++++++++----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index 84e519ad685..8c64e3e680e 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -468,7 +468,7 @@
         "description": "winsys/amdgpu: fix a mutex deadlock when we fail to create pipe_screen",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "because_sha": "2eb067db0febcd71b4182153155e3e43f215624c"
     },
     {
diff --git a/src/gallium/winsys/amdgpu/drm/amdgpu_winsys.c b/src/gallium/winsys/amdgpu/drm/amdgpu_winsys.c
index d042bc2472f..cc71b0e920b 100644
--- a/src/gallium/winsys/amdgpu/drm/amdgpu_winsys.c
+++ b/src/gallium/winsys/amdgpu/drm/amdgpu_winsys.c
@@ -155,7 +155,7 @@ static void do_winsys_deinit(struct amdgpu_winsys *ws)
    FREE(ws);
 }
 
-static void amdgpu_winsys_destroy(struct radeon_winsys *rws)
+static void amdgpu_winsys_destroy_locked(struct radeon_winsys *rws, bool locked)
 {
    struct amdgpu_screen_winsys *sws = amdgpu_screen_winsys(rws);
    struct amdgpu_winsys *ws = sws->aws;
@@ -167,7 +167,8 @@ static void amdgpu_winsys_destroy(struct radeon_winsys *rws)
     * amdgpu_winsys_create in another thread doesn't get the winsys
     * from the table when the counter drops to 0.
     */
-   simple_mtx_lock(&dev_tab_mutex);
+   if (!locked)
+      simple_mtx_lock(&dev_tab_mutex);
 
    destroy = pipe_reference(&ws->reference, NULL);
    if (destroy && dev_tab) {
@@ -178,7 +179,8 @@ static void amdgpu_winsys_destroy(struct radeon_winsys *rws)
       }
    }
 
-   simple_mtx_unlock(&dev_tab_mutex);
+   if (!locked)
+      simple_mtx_unlock(&dev_tab_mutex);
 
    if (destroy)
       do_winsys_deinit(ws);
@@ -187,6 +189,11 @@ static void amdgpu_winsys_destroy(struct radeon_winsys *rws)
    FREE(rws);
 }
 
+static void amdgpu_winsys_destroy(struct radeon_winsys *rws)
+{
+   amdgpu_winsys_destroy_locked(rws, false);
+}
+
 static void amdgpu_winsys_query_info(struct radeon_winsys *rws,
                                      struct radeon_info *info,
                                      bool enable_smart_access_memory,
@@ -556,7 +563,7 @@ amdgpu_winsys_create(int fd, const struct pipe_screen_config *config,
     * and link all drivers into one binary blob. */
    ws->base.screen = screen_create(&ws->base, config);
    if (!ws->base.screen) {
-      amdgpu_winsys_destroy(&ws->base);
+      amdgpu_winsys_destroy_locked(&ws->base, true);
       simple_mtx_unlock(&dev_tab_mutex);
       return NULL;
    }