drm/msm: skip re-emitting IBs for unusable VMs

When a VM is marked as an usuable we disallow new submissions from it,
however submissions that where already scheduled on the ring would still
be re-sent.

Since this can lead to further hangs, avoid emitting the actual IBs.

Fixes: 6a4d287 ("drm/msm: Mark VM as unusable on GPU hangs")
Signed-off-by: Antonino Maniscalco <antomani103@gmail.com>
Reviewed-by: Akhil P Oommen <akhilpo@oss.qualcomm.com>
Patchwork: https://patchwork.freedesktop.org/patch/668314/
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>

Author: pac85

drivers/gpu/drm/msm/msm_gpu.c

@@ -558,8 +558,15 @@ static void recover_worker(struct kthread_work *work)
 			unsigned long flags;
 
 			spin_lock_irqsave(&ring->submit_lock, flags);
-			list_for_each_entry(submit, &ring->submits, node)
+			list_for_each_entry(submit, &ring->submits, node) {
+				/*
+				 * If the submit uses an unusable vm make sure
+				 * we don't actually run it
+				 */
+				if (to_msm_vm(submit->vm)->unusable)
+					submit->nr_cmds = 0;
 				gpu->funcs->submit(gpu, submit);
+			}
 			spin_unlock_irqrestore(&ring->submit_lock, flags);
 		}
 	}