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From: Dave Airlie <airlied@gmail.com>
To: dri-devel@lists.freedesktop.org
Cc: nouveau@lists.freedesktop.org
Subject: [PATCH] nouveau: rip out busy fence waits
Date: Wed, 17 Apr 2024 15:40:32 +1000	[thread overview]
Message-ID: <20240417054032.3145721-1-airlied@gmail.com> (raw)

From: Dave Airlie <airlied@redhat.com>

I'm pretty sure this optimisation is actually not a great idea,
and is racy with other things waiting for fences.

Just nuke it, there should be no need to do fence waits in a
busy CPU loop.

Signed-off-by: Dave Airlie <airlied@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_bo.c    |  2 +-
 drivers/gpu/drm/nouveau/nouveau_chan.c  |  2 +-
 drivers/gpu/drm/nouveau/nouveau_dmem.c  |  2 +-
 drivers/gpu/drm/nouveau/nouveau_fence.c | 30 +------------------------
 drivers/gpu/drm/nouveau/nouveau_fence.h |  2 +-
 drivers/gpu/drm/nouveau/nouveau_gem.c   |  2 +-
 6 files changed, 6 insertions(+), 34 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
index 8a30f5a0525b..a4e8f625fce6 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -902,7 +902,7 @@ nouveau_bo_move_m2mf(struct ttm_buffer_object *bo, int evict,
 	 * Without this the operation can timeout and we'll fallback to a
 	 * software copy, which might take several minutes to finish.
 	 */
-	nouveau_fence_wait(fence, false, false);
+	nouveau_fence_wait(fence, false);
 	ret = ttm_bo_move_accel_cleanup(bo, &fence->base, evict, false,
 					new_reg);
 	nouveau_fence_unref(&fence);
diff --git a/drivers/gpu/drm/nouveau/nouveau_chan.c b/drivers/gpu/drm/nouveau/nouveau_chan.c
index 7c97b2886807..66fca95c10c7 100644
--- a/drivers/gpu/drm/nouveau/nouveau_chan.c
+++ b/drivers/gpu/drm/nouveau/nouveau_chan.c
@@ -72,7 +72,7 @@ nouveau_channel_idle(struct nouveau_channel *chan)
 
 		ret = nouveau_fence_new(&fence, chan);
 		if (!ret) {
-			ret = nouveau_fence_wait(fence, false, false);
+			ret = nouveau_fence_wait(fence, false);
 			nouveau_fence_unref(&fence);
 		}
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_dmem.c b/drivers/gpu/drm/nouveau/nouveau_dmem.c
index 12feecf71e75..033a09cd3c8f 100644
--- a/drivers/gpu/drm/nouveau/nouveau_dmem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_dmem.c
@@ -128,7 +128,7 @@ static void nouveau_dmem_page_free(struct page *page)
 static void nouveau_dmem_fence_done(struct nouveau_fence **fence)
 {
 	if (fence) {
-		nouveau_fence_wait(*fence, true, false);
+		nouveau_fence_wait(*fence, false);
 		nouveau_fence_unref(fence);
 	} else {
 		/*
diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
index c3ea3cd933cd..8de941379324 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fence.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
@@ -312,39 +312,11 @@ nouveau_fence_wait_legacy(struct dma_fence *f, bool intr, long wait)
 	return timeout - t;
 }
 
-static int
-nouveau_fence_wait_busy(struct nouveau_fence *fence, bool intr)
-{
-	int ret = 0;
-
-	while (!nouveau_fence_done(fence)) {
-		if (time_after_eq(jiffies, fence->timeout)) {
-			ret = -EBUSY;
-			break;
-		}
-
-		__set_current_state(intr ?
-				    TASK_INTERRUPTIBLE :
-				    TASK_UNINTERRUPTIBLE);
-
-		if (intr && signal_pending(current)) {
-			ret = -ERESTARTSYS;
-			break;
-		}
-	}
-
-	__set_current_state(TASK_RUNNING);
-	return ret;
-}
-
 int
-nouveau_fence_wait(struct nouveau_fence *fence, bool lazy, bool intr)
+nouveau_fence_wait(struct nouveau_fence *fence, bool intr)
 {
 	long ret;
 
-	if (!lazy)
-		return nouveau_fence_wait_busy(fence, intr);
-
 	ret = dma_fence_wait_timeout(&fence->base, intr, 15 * HZ);
 	if (ret < 0)
 		return ret;
diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.h b/drivers/gpu/drm/nouveau/nouveau_fence.h
index bc13110bdfa4..88213014b675 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fence.h
+++ b/drivers/gpu/drm/nouveau/nouveau_fence.h
@@ -23,7 +23,7 @@ void nouveau_fence_unref(struct nouveau_fence **);
 
 int  nouveau_fence_emit(struct nouveau_fence *);
 bool nouveau_fence_done(struct nouveau_fence *);
-int  nouveau_fence_wait(struct nouveau_fence *, bool lazy, bool intr);
+int  nouveau_fence_wait(struct nouveau_fence *, bool intr);
 int  nouveau_fence_sync(struct nouveau_bo *, struct nouveau_channel *, bool exclusive, bool intr);
 
 struct nouveau_fence_chan {
diff --git a/drivers/gpu/drm/nouveau/nouveau_gem.c b/drivers/gpu/drm/nouveau/nouveau_gem.c
index 49c2bcbef129..f715e381da69 100644
--- a/drivers/gpu/drm/nouveau/nouveau_gem.c
+++ b/drivers/gpu/drm/nouveau/nouveau_gem.c
@@ -928,7 +928,7 @@ nouveau_gem_ioctl_pushbuf(struct drm_device *dev, void *data,
 	}
 
 	if (sync) {
-		if (!(ret = nouveau_fence_wait(fence, false, false))) {
+		if (!(ret = nouveau_fence_wait(fence, false))) {
 			if ((ret = dma_fence_get_status(&fence->base)) == 1)
 				ret = 0;
 		}
-- 
2.43.2


                 reply	other threads:[~2024-04-17  5:40 UTC|newest]

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