linux-kernel - [PATCH 3.16 156/192] drm/irq: BUG_ON() -> WARN

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Message-ID: <lsq.1507553065.365609203@decadent.org.uk>
Date:   Mon, 09 Oct 2017 13:44:25 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Rob Clark" <robdclark@...il.com>,
        "Dave Airlie" <airlied@...hat.com>,
        "Michel Dänzer" <michel.daenzer@....com>
Subject: [PATCH 3.16 156/192] drm/irq: BUG_ON() -> WARN_ON()

3.16.49-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Rob Clark <robdclark@...il.com>

commit 7f907bf284ba7bb8d271f094b226699d3fef2142 upstream.

Let's make things a bit easier to debug when things go bad (potentially
under console_lock).

Signed-off-by: Rob Clark <robdclark@...il.com>
Reviewed-by: Michel Dänzer <michel.daenzer@....com>
Signed-off-by: Dave Airlie <airlied@...hat.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/gpu/drm/drm_irq.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpu/drm/drm_irq.c
+++ b/drivers/gpu/drm/drm_irq.c
@@ -973,7 +973,8 @@ EXPORT_SYMBOL(drm_crtc_vblank_get);
  */
 void drm_vblank_put(struct drm_device *dev, int crtc)
 {
-	BUG_ON(atomic_read(&dev->vblank[crtc].refcount) == 0);
+	if (WARN_ON(atomic_read(&dev->vblank[crtc].refcount) == 0))
+		return;
 
 	/* Last user schedules interrupt disable */
 	if (atomic_dec_and_test(&dev->vblank[crtc].refcount) &&