From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed, 3 Jul 2019 17:19:13 +0000 (+0100)
Subject: drm/i915: Flush the workqueue before draining
X-Git-Tag: v5.4-rc1~106^2~19^2~221
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=4fda44bf16b79a0b78fe36c6b9859e9ce2d09f43;p=linux.git

drm/i915: Flush the workqueue before draining

Trying to drain a workqueue while we may still be adding to it from
background tasks is, according to kernel/workqueue.c, verboten. So, add
a flush_workqueue() at the start of our cleanup procedure.

References: https://bugs.freedesktop.org/show_bug.cgi?id=110550
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190703171913.16585-4-chris@chris-wilson.co.uk
---

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index ca3afe6e95b5..a4ae9ea298dd 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2473,6 +2473,7 @@ static inline void i915_gem_drain_workqueue(struct drm_i915_private *i915)
 	 */
 	int pass = 3;
 	do {
+		flush_workqueue(i915->wq);
 		rcu_barrier();
 		i915_gem_drain_freed_objects(i915);
 	} while (--pass);