[PATCH] Fix deadlock between fb_info and console. Do not lockfb_info when calling sending the FB_EVENT_CONBLANK

From: John Tapsell
Date: Thu Sep 12 2013 - 04:16:12 EST


In fbmem.c, the semantics are that we acquire the lock_fb_info first,
and then console_lock. However when fbcon.c fbcon_generic_blank() is
called, the console lock could already be held. Locking fb_info can
thus cause a deadlock.

fbmem.c sends the FB_EVENT_BLANK without locking lock_fb_info first, so
this change introduces similar behaviour.
---
drivers/video/console/fbcon.c | 4 ----
1 file changed, 4 deletions(-)

diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
index 6b4fb5c..8546441 100644
--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -2333,13 +2333,9 @@ static void fbcon_generic_blank(struct vc_data *vc,
struct fb_info *info,
vc->vc_video_erase_char = oldc;
}

-
- if (!lock_fb_info(info))
- return;
event.info = info;
event.data = ␣
fb_notifier_call_chain(FB_EVENT_CONBLANK, &event);
- unlock_fb_info(info);
}

static int fbcon_blank(struct vc_data *vc, int blank, int mode_switch)
--
1.8.1.2


How can I get this reviewed/acked please?



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