From 139174042d200fd399f83a2a84b5165bfc70ef1a Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu, 23 Jan 2020 22:44:59 +0000
Subject: drm/i915: Wait on vma activity before taking the mutex
Git-commit: d62f416f925dc615256193c76aebd582ae88bcaf
Patch-mainline: v5.7-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

Optimistically wait for the prior vma activity before taking the mutex
to minimise the mutex hold time while unbinding. We will then verify the
vma is idle with a second wait under the mutex to ensure it is safe to
unbind.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200123224459.38128-2-chris@chris-wilson.co.uk
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/i915_vma.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index 4999882fbceb..84e03da0d5f9 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -1279,16 +1279,21 @@ int i915_vma_unbind(struct i915_vma *vma)
 		/* XXX not always required: nop_clear_range */
 		wakeref = intel_runtime_pm_get(&vm->i915->runtime_pm);
 
+	/* Optimistic wait before taking the mutex */
+	err = i915_vma_sync(vma);
+	if (err)
+		goto out_rpm;
+
 	err = mutex_lock_interruptible(&vm->mutex);
 	if (err)
-		return err;
+		goto out_rpm;
 
 	err = __i915_vma_unbind(vma);
 	mutex_unlock(&vm->mutex);
 
+out_rpm:
 	if (wakeref)
 		intel_runtime_pm_put(&vm->i915->runtime_pm, wakeref);
-
 	return err;
 }
 
-- 
2.28.0