Mesa (main): st/mesa: use mutex in st_get_texture_sampler_view_from_stobj

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Module: Mesa
Branch: main
Commit: b51e40ebdecea4bfe0afa8200d068fc35798596f
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=b51e40ebdecea4bfe0afa8200d068fc35798596f

Author: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer at amd.com>
Date:   Thu May 19 10:57:40 2022 +0200

st/mesa: use mutex in st_get_texture_sampler_view_from_stobj

st_texture_release_all_sampler_views uses the validate_mutex,
but st_get_texture_sampler_view_from_stobj didn't.

Since they both modify stObj->view we could have threadA in
st_get_texture_sampler_view_from_stobj with a non-NULL sv,
so expecting sv->view to be non-NULL, while threadB was in
st_texture_release_all_sampler_views clearing sv->view.

It's also needed to protect st_sampler_view::private_refcount,
which is supposed to be used from the owning context thread,
but can also be used by any context in st_texture_release_all_sampler_views.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/6088
Fixes: ef5d4274132 ("st/mesa: add a mechanism to bypass atomics when binding sampler views")
Reviewed-by: Marek Olšák <marek.olsak at amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16779>

---

 src/mesa/state_tracker/st_sampler_view.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/mesa/state_tracker/st_sampler_view.c b/src/mesa/state_tracker/st_sampler_view.c
index 969cfa90d72..c3f665b7921 100644
--- a/src/mesa/state_tracker/st_sampler_view.c
+++ b/src/mesa/state_tracker/st_sampler_view.c
@@ -87,14 +87,15 @@ st_texture_set_sampler_view(struct st_context *st,
                             struct gl_texture_object *stObj,
                             struct pipe_sampler_view *view,
                             bool glsl130_or_later, bool srgb_skip_decode,
-                            bool get_reference)
+                            bool get_reference, bool locked)
 {
    struct st_sampler_views *views;
    struct st_sampler_view *free = NULL;
    struct st_sampler_view *sv;
    GLuint i;
 
-   simple_mtx_lock(&stObj->validate_mutex);
+   if (!locked)
+      simple_mtx_lock(&stObj->validate_mutex);
    views = stObj->sampler_views;
 
    for (i = 0; i < views->count; ++i) {
@@ -187,7 +188,8 @@ found:
       view = get_sampler_view_reference(sv, view);
 
 out:
-   simple_mtx_unlock(&stObj->validate_mutex);
+   if (!locked)
+      simple_mtx_unlock(&stObj->validate_mutex);
    return view;
 }
 
@@ -633,6 +635,7 @@ st_get_texture_sampler_view_from_stobj(struct st_context *st,
    if (!ignore_srgb_decode && samp->Attrib.sRGBDecode == GL_SKIP_DECODE_EXT)
       srgb_skip_decode = true;
 
+   simple_mtx_lock(&texObj->validate_mutex);
    sv = st_texture_get_current_sampler_view(st, texObj);
 
    if (sv &&
@@ -658,6 +661,7 @@ st_get_texture_sampler_view_from_stobj(struct st_context *st,
               texObj->layer_override == view->u.tex.last_layer));
       if (get_reference)
          view = get_sampler_view_reference(sv, view);
+      simple_mtx_unlock(&texObj->validate_mutex);
       return view;
    }
 
@@ -670,7 +674,9 @@ st_get_texture_sampler_view_from_stobj(struct st_context *st,
 
    view = st_texture_set_sampler_view(st, texObj, view,
                                       glsl130_or_later, srgb_skip_decode,
-                                      get_reference);
+                                      get_reference, true);
+   simple_mtx_unlock(&texObj->validate_mutex);
+
    return view;
 }
 
@@ -742,7 +748,7 @@ st_get_buffer_sampler_view_from_stobj(struct st_context *st,
       st->pipe->create_sampler_view(st->pipe, buf, &templ);
 
    view = st_texture_set_sampler_view(st, texObj, view, false, false,
-                                      get_reference);
+                                      get_reference, false);
 
    return view;
 }