From 947a333ec3c741668024a9a7cb3002cca082a0b2 Mon Sep 17 00:00:00 2001
From: Tatsuyuki Ishi <ishitatsuyuki@gmail.com>
Date: Tue, 23 Jul 2024 00:06:05 +0900
Subject: [PATCH] util/u_queue: Replace relative time wait hack with
 u_cnd_monotonic
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Remove the gross hack. The hack was broken too, because it incorrectly
added abs_time (a timestamp) to the now (another timestamp).

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30491>
---
 src/util/u_queue.c | 39 ++++++++++++---------------------------
 src/util/u_queue.h |  3 ++-
 2 files changed, 14 insertions(+), 28 deletions(-)

diff --git a/src/util/u_queue.c b/src/util/u_queue.c
index 750dd2015a6..026e1582a22 100644
--- a/src/util/u_queue.c
+++ b/src/util/u_queue.c
@@ -31,6 +31,7 @@
 #include "util/os_time.h"
 #include "util/u_string.h"
 #include "util/u_thread.h"
+#include "util/timespec.h"
 #include "u_process.h"
 
 #if defined(__linux__)
@@ -160,7 +161,7 @@ util_queue_fence_signal(struct util_queue_fence *fence)
 {
    mtx_lock(&fence->mutex);
    fence->signalled = true;
-   cnd_broadcast(&fence->cond);
+   u_cnd_monotonic_broadcast(&fence->cond);
    mtx_unlock(&fence->mutex);
 }
 
@@ -169,7 +170,7 @@ _util_queue_fence_wait(struct util_queue_fence *fence)
 {
    mtx_lock(&fence->mutex);
    while (!fence->signalled)
-      cnd_wait(&fence->cond, &fence->mutex);
+      u_cnd_monotonic_wait(&fence->cond, &fence->mutex);
    mtx_unlock(&fence->mutex);
 }
 
@@ -177,31 +178,15 @@ bool
 _util_queue_fence_wait_timeout(struct util_queue_fence *fence,
                                int64_t abs_timeout)
 {
-   /* This terrible hack is made necessary by the fact that we really want an
-    * internal interface consistent with os_time_*, but cnd_timedwait is spec'd
-    * to be relative to the TIME_UTC clock.
-    */
-   int64_t rel = abs_timeout - os_time_get_nano();
+   struct timespec ts;
+   timespec_from_nsec(&ts, abs_timeout);
 
-   if (rel > 0) {
-      struct timespec ts;
-
-      timespec_get(&ts, TIME_UTC);
-
-      ts.tv_sec += abs_timeout / (1000*1000*1000);
-      ts.tv_nsec += abs_timeout % (1000*1000*1000);
-      if (ts.tv_nsec >= (1000*1000*1000)) {
-         ts.tv_sec++;
-         ts.tv_nsec -= (1000*1000*1000);
-      }
-
-      mtx_lock(&fence->mutex);
-      while (!fence->signalled) {
-         if (cnd_timedwait(&fence->cond, &fence->mutex, &ts) != thrd_success)
-            break;
-      }
-      mtx_unlock(&fence->mutex);
+   mtx_lock(&fence->mutex);
+   while (!fence->signalled) {
+      if (u_cnd_monotonic_timedwait(&fence->cond, &fence->mutex, &ts) != thrd_success)
+         break;
    }
+   mtx_unlock(&fence->mutex);
 
    return fence->signalled;
 }
@@ -211,7 +196,7 @@ util_queue_fence_init(struct util_queue_fence *fence)
 {
    memset(fence, 0, sizeof(*fence));
    (void) mtx_init(&fence->mutex, mtx_plain);
-   cnd_init(&fence->cond);
+   u_cnd_monotonic_init(&fence->cond);
    fence->signalled = true;
 }
 
@@ -232,7 +217,7 @@ util_queue_fence_destroy(struct util_queue_fence *fence)
    mtx_lock(&fence->mutex);
    mtx_unlock(&fence->mutex);
 
-   cnd_destroy(&fence->cond);
+   u_cnd_monotonic_destroy(&fence->cond);
    mtx_destroy(&fence->mutex);
 }
 #endif
diff --git a/src/util/u_queue.h b/src/util/u_queue.h
index 2d5ef91bc91..a1b26994365 100644
--- a/src/util/u_queue.h
+++ b/src/util/u_queue.h
@@ -35,6 +35,7 @@
 
 #include <string.h>
 
+#include "cnd_monotonic.h"
 #include "simple_mtx.h"
 #include "util/futex.h"
 #include "util/list.h"
@@ -124,7 +125,7 @@ util_queue_fence_is_signalled(struct util_queue_fence *fence)
  */
 struct util_queue_fence {
    mtx_t mutex;
-   cnd_t cond;
+   struct u_cnd_monotonic cond;
    int signalled;
 };