Possible fix NULL pointer dereference during VC4 binding

0001-drm-vc4-Fix-race-during-binding.patch

From 88bffea2fd7a573f7e9659b188a125cd9842f79b Mon Sep 17 00:00:00 2001
From: Stefan Wahren <[email protected]>
Date: Sat, 30 Sep 2017 13:28:40 +0200
Subject: [PATCH] drm: vc4: Fix race during binding

This fixes the race between vc4_overflow_mem_work and the init of the
job lock. Otherwise we could trigger a NULL pointer dereference
during binding.

Signed-off-by: Stefan Wahren <[email protected]>
---
 drivers/gpu/drm/vc4/vc4_gem.c | 1 -
 drivers/gpu/drm/vc4/vc4_irq.c | 1 +
 2 files changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_gem.c b/drivers/gpu/drm/vc4/vc4_gem.c
index 994295f..c869ad0 100644
--- a/drivers/gpu/drm/vc4/vc4_gem.c
+++ b/drivers/gpu/drm/vc4/vc4_gem.c
@@ -934,7 +934,6 @@ vc4_gem_init(struct drm_device *dev)
 	INIT_LIST_HEAD(&vc4->render_job_list);
 	INIT_LIST_HEAD(&vc4->job_done_list);
 	INIT_LIST_HEAD(&vc4->seqno_cb_list);
-	spin_lock_init(&vc4->job_lock);
 
 	INIT_WORK(&vc4->hangcheck.reset_work, vc4_reset_work);
 	setup_timer(&vc4->hangcheck.timer,
diff --git a/drivers/gpu/drm/vc4/vc4_irq.c b/drivers/gpu/drm/vc4/vc4_irq.c
index c43ee1e..2a0a7a7 100644
--- a/drivers/gpu/drm/vc4/vc4_irq.c
+++ b/drivers/gpu/drm/vc4/vc4_irq.c
@@ -190,6 +190,7 @@ vc4_irq_preinstall(struct drm_device *dev)
 	struct vc4_dev *vc4 = to_vc4_dev(dev);
 
 	init_waitqueue_head(&vc4->job_wait_queue);
+	spin_lock_init(&vc4->job_lock);
 	INIT_WORK(&vc4->overflow_mem_work, vc4_overflow_mem_work);
 
 	/* Clear any pending interrupts someone might have left around
-- 
2.7.4