[src/trunk]: src/sys/external/bsd/drm2/linux drm: Rework enable-signal logic ...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/dc3e73810da1
branches:  trunk
changeset: 1028815:dc3e73810da1
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Sun Dec 19 12:07:38 2021 +0000

description:
drm: Rework enable-signal logic to match Linux.

diffstat:

 sys/external/bsd/drm2/linux/linux_dma_fence.c |  30 +++++++++++++++-----------
 1 files changed, 17 insertions(+), 13 deletions(-)

diffs (61 lines):

diff -r afef3ac176b6 -r dc3e73810da1 sys/external/bsd/drm2/linux/linux_dma_fence.c
--- a/sys/external/bsd/drm2/linux/linux_dma_fence.c     Sun Dec 19 12:07:29 2021 +0000
+++ b/sys/external/bsd/drm2/linux/linux_dma_fence.c     Sun Dec 19 12:07:38 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: linux_dma_fence.c,v 1.19 2021/12/19 12:02:40 riastradh Exp $   */
+/*     $NetBSD: linux_dma_fence.c,v 1.20 2021/12/19 12:07:38 riastradh Exp $   */
 
 /*-
  * Copyright (c) 2018 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: linux_dma_fence.c,v 1.19 2021/12/19 12:02:40 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: linux_dma_fence.c,v 1.20 2021/12/19 12:07:38 riastradh Exp $");
 
 #include <sys/atomic.h>
 #include <sys/condvar.h>
@@ -344,27 +344,31 @@
 static int
 dma_fence_ensure_signal_enabled(struct dma_fence *fence)
 {
+       bool already_enabled;
 
        KASSERT(dma_fence_referenced_p(fence));
        KASSERT(spin_is_locked(fence->lock));
 
+       /* Determine whether signalling was enabled, and enable it.  */
+       already_enabled = test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
+           &fence->flags);
+
        /* If the fence was already signalled, fail with -ENOENT.  */
        if (fence->flags & (1u << DMA_FENCE_FLAG_SIGNALED_BIT))
                return -ENOENT;
 
        /*
-        * If the enable signaling callback has been called, success.
-        * Otherwise, set the bit indicating it.
+        * Otherwise, if it wasn't enabled yet, try to enable
+        * signalling, or fail if the fence doesn't support that.
         */
-       if (test_and_set_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT, &fence->flags))
-               return 0;
-
-       /* Otherwise, note that we've called it and call it.  */
-       KASSERT(fence->ops->enable_signaling);
-       if (!(*fence->ops->enable_signaling)(fence)) {
-               /* If it failed, signal and return -ENOENT.  */
-               dma_fence_signal_locked(fence);
-               return -ENOENT;
+       if (!already_enabled) {
+               if (fence->ops->enable_signaling == NULL)
+                       return -ENOENT;
+               if (!(*fence->ops->enable_signaling)(fence)) {
+                       /* If it failed, signal and return -ENOENT.  */
+                       dma_fence_signal_locked(fence);
+                       return -ENOENT;
+               }
        }
 
        /* Success!  */