From f14e9c6f4c503218b046e3e6323cbd2ee350a687 Mon Sep 17 00:00:00 2001
From: njsyw1997 <44545837+njsyw1997@users.noreply.github.com>
Date: Sat, 11 Apr 2026 16:32:52 -0700
Subject: [PATCH] hexagon: fix futex race in hmx_worker_drain Store the boolean
 to local variable avoid atomic load twice

---
 ggml/src/ggml-hexagon/htp/hmx-worker.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/ggml/src/ggml-hexagon/htp/hmx-worker.c b/ggml/src/ggml-hexagon/htp/hmx-worker.c
index 6826dde7de..013173c7e5 100644
--- a/ggml/src/ggml-hexagon/htp/hmx-worker.c
+++ b/ggml/src/ggml-hexagon/htp/hmx-worker.c
@@ -98,8 +98,15 @@ static void hmx_worker_issue(struct hmx_worker_context * ctx,
 // Block until the worker has completed the most recently issued command.
 static void hmx_worker_drain(struct hmx_worker_context * ctx) {
     unsigned int expected = atomic_load_explicit(&ctx->cmd_seqn, memory_order_acquire);
-    while (atomic_load_explicit(&ctx->done_seqn, memory_order_acquire) != expected) {
-        qurt_futex_wait(&ctx->done_seqn, atomic_load_explicit(&ctx->done_seqn, memory_order_relaxed));
+    for (;;) {
+        unsigned int seen = atomic_load_explicit(&ctx->done_seqn, memory_order_acquire);
+        if (seen == expected) {
+            return;
+        }
+        // Pass the same observed value to futex_wait().  If the worker completes
+        // between the load above and the futex call, the value mismatch makes the
+        // wait return immediately instead of sleeping forever on the new seqn.
+        qurt_futex_wait(&ctx->done_seqn, seen);
     }
 }