Mesa (staging/20.0): util/sparse_free_list: manipulate node pointers using atomic primitives

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Module: Mesa
Branch: staging/20.0
Commit: eb39c5fb4f8f30a203e20abd14f13c30fe28b8d8
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=eb39c5fb4f8f30a203e20abd14f13c30fe28b8d8

Author: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Date:   Fri Apr 17 20:42:41 2020 +0300

util/sparse_free_list: manipulate node pointers using atomic primitives

Probably doesn't fix anything but those should be accessed in an
atomic way just like the head pointer.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
Fixes: e4f01eca3b3cd1 ("util: Add a free list structure for use with util_sparse_array")
Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4613>
(cherry picked from commit cdc43775917e301a7ca654fcebb94fad08dc4131)

---

 .pick_status.json       | 2 +-
 src/util/sparse_array.c | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/.pick_status.json b/.pick_status.json
index f89d75a2ef0..839d00f452c 100644
--- a/.pick_status.json
+++ b/.pick_status.json
@@ -238,7 +238,7 @@
         "description": "util/sparse_free_list: manipulate node pointers using atomic primitives",
         "nominated": true,
         "nomination_type": 1,
-        "resolution": 0,
+        "resolution": 1,
         "master_sha": null,
         "because_sha": "e4f01eca3b3cd1701f21cacbb8d29fe688ba42bb"
     },
diff --git a/src/util/sparse_array.c b/src/util/sparse_array.c
index 39420473420..4691adcc88d 100644
--- a/src/util/sparse_array.c
+++ b/src/util/sparse_array.c
@@ -220,7 +220,7 @@ util_sparse_array_free_list_push(struct util_sparse_array_free_list *fl,
    void *last_elem = util_sparse_array_get(fl->arr, items[0]);
    uint32_t *last_next = (uint32_t *)((char *)last_elem + fl->next_offset);
    for (unsigned i = 1; i < num_items; i++) {
-      *last_next = items[i];
+      p_atomic_set(last_next, items[i]);
       assert(items[i] != fl->sentinel);
       last_elem = util_sparse_array_get(fl->arr, items[i]);
       last_next = (uint32_t *)((char *)last_elem + fl->next_offset);
@@ -230,7 +230,7 @@ util_sparse_array_free_list_push(struct util_sparse_array_free_list *fl,
    old_head = p_atomic_read(&fl->head);
    do {
       current_head = old_head;
-      *last_next = current_head; /* Index is the bottom 32 bits */
+      p_atomic_set(last_next, (uint32_t)current_head); /* Index is the bottom 32 bits */
       uint64_t new_head = free_list_head(current_head, items[0]);
       old_head = p_atomic_cmpxchg(&fl->head, current_head, new_head);
    } while (old_head != current_head);
@@ -249,7 +249,7 @@ util_sparse_array_free_list_pop_idx(struct util_sparse_array_free_list *fl)
       uint32_t head_idx = current_head; /* Index is the bottom 32 bits */
       void *head_elem = util_sparse_array_get(fl->arr, head_idx);
       uint32_t *head_next = (uint32_t *)((char *)head_elem + fl->next_offset);
-      uint64_t new_head = free_list_head(current_head, *head_next);
+      uint64_t new_head = free_list_head(current_head, p_atomic_read(head_next));
       uint64_t old_head = p_atomic_cmpxchg(&fl->head, current_head, new_head);
       if (old_head == current_head)
          return head_idx;
@@ -270,7 +270,7 @@ util_sparse_array_free_list_pop_elem(struct util_sparse_array_free_list *fl)
       uint32_t head_idx = current_head; /* Index is the bottom 32 bits */
       void *head_elem = util_sparse_array_get(fl->arr, head_idx);
       uint32_t *head_next = (uint32_t *)((char *)head_elem + fl->next_offset);
-      uint64_t new_head = free_list_head(current_head, *head_next);
+      uint64_t new_head = free_list_head(current_head, p_atomic_read(head_next));
       uint64_t old_head = p_atomic_cmpxchg(&fl->head, current_head, new_head);
       if (old_head == current_head)
          return head_elem;