From 87d3b6588f9bf205902868d3e5baf68e37ad4ae1 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Thu, 20 Oct 2016 17:05:30 +0200
Subject: [PATCH] drm/fb-helper: Don't call dirty callback for untouched clips
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Since 4.7 kernel, we've seen the error messages like
kernel: [TTM] Buffer eviction failed
kernel: qxl 0000:00:02.0: object_init failed for (4026540032, 0x00000001)
kernel: [drm:qxl_alloc_bo_reserved [qxl]] *ERROR* failed to allocate VRAM BO
on QXL when switching and accessing on VT. The culprit was the
generic deferred_io code (qxl driver switched to it since 4.7).
There is a race between the dirty clip update and the call of
callback.
In drm_fb_helper_dirty(), the dirty clip is updated in the spinlock,
while it kicks off the update worker outside the spinlock. Meanwhile
the update worker clears the dirty clip in the spinlock, too. Thus,
when drm_fb_helper_dirty() is called concurrently, schedule_work() is
called after the clip is cleared in the first worker call.
This patch addresses it by validating the clip before calling the
dirty fb callback.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98322
Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1003298
Fixes: eaa434defaca ('drm/fb-helper: Add fb_deferred_io support')
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20161020150530.5787-1-tiwai@suse.de
---
drivers/gpu/drm/drm_fb_helper.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 03414bde1f15..aae7df01864d 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -644,7 +644,9 @@ static void drm_fb_helper_dirty_work(struct work_struct *work)
clip->x2 = clip->y2 = 0;
spin_unlock_irqrestore(&helper->dirty_lock, flags);
- helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, &clip_copy, 1);
+ /* call dirty callback only when it has been really touched */
+ if (clip_copy.x1 < clip_copy.x2 && clip_copy.y1 < clip_copy.y2)
+ helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, &clip_copy, 1);
}
/**
--
2.30.9