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From:   Danilo Krummrich <dakr@redhat.com>
To:     daniel@ffwll.ch, airlied@redhat.com, christian.koenig@amd.com,
        bskeggs@redhat.com, jason@jlekstrand.net, tzimmermann@suse.de,
        mripard@kernel.org, corbet@lwn.net
Cc:     dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        Danilo Krummrich <dakr@redhat.com>
Subject: [PATCH drm-next 09/14] drm/nouveau: fence: fail to emit when fence context is killed
Date:   Wed, 18 Jan 2023 07:12:51 +0100
Message-Id: <20230118061256.2689-10-dakr@redhat.com>
In-Reply-To: <20230118061256.2689-1-dakr@redhat.com>
References: <20230118061256.2689-1-dakr@redhat.com>
MIME-Version: 1.0
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The new VM_BIND UAPI implementation introduced in subsequent commits
will allow asynchronous jobs processing push buffers and emitting
fences.

If a fence context is killed, e.g. due to a channel fault, jobs which
are already queued for execution might still emit new fences. In such a
case a job would hang forever.

To fix that, fail to emit a new fence on a killed fence context with
-ENODEV to unblock the job.

Signed-off-by: Danilo Krummrich <dakr@redhat.com>
---
 drivers/gpu/drm/nouveau/nouveau_fence.c | 7 +++++++
 drivers/gpu/drm/nouveau/nouveau_fence.h | 2 +-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.c b/drivers/gpu/drm/nouveau/nouveau_fence.c
index ee5e9d40c166..62c70d9a32e6 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fence.c
+++ b/drivers/gpu/drm/nouveau/nouveau_fence.c
@@ -96,6 +96,7 @@ nouveau_fence_context_kill(struct nouveau_fence_chan *fctx, int error)
 		if (nouveau_fence_signal(fence))
 			nvif_event_block(&fctx->event);
 	}
+	fctx->killed = 1;
 	spin_unlock_irqrestore(&fctx->lock, flags);
 }
 
@@ -226,6 +227,12 @@ nouveau_fence_emit(struct nouveau_fence *fence, struct nouveau_channel *chan)
 		dma_fence_get(&fence->base);
 		spin_lock_irq(&fctx->lock);
 
+		if (unlikely(fctx->killed)) {
+			spin_unlock_irq(&fctx->lock);
+			dma_fence_put(&fence->base);
+			return -ENODEV;
+		}
+
 		if (nouveau_fence_update(chan, fctx))
 			nvif_event_block(&fctx->event);
 
diff --git a/drivers/gpu/drm/nouveau/nouveau_fence.h b/drivers/gpu/drm/nouveau/nouveau_fence.h
index 0ca2bc85adf6..00a08699bb58 100644
--- a/drivers/gpu/drm/nouveau/nouveau_fence.h
+++ b/drivers/gpu/drm/nouveau/nouveau_fence.h
@@ -45,7 +45,7 @@ struct nouveau_fence_chan {
 	char name[32];
 
 	struct nvif_event event;
-	int notify_ref, dead;
+	int notify_ref, dead, killed;
 };
 
 struct nouveau_fence_priv {
-- 
2.39.0