From 8a259cfd2241c12ad7e18badddafd502a79d9a7f Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Thu, 17 Nov 2011 10:41:06 +1100 Subject: [PATCH] drm: avoid switching to text console if there is no panic timeout MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Add a check for panic_timeout in the drm_fb_helper_panic() notifier: if we're going to reboot immediately, the user will not be able to see the messages anyway, and messing with the video mode may display artifacts, and certainly get into several layers of complexity (including mutexes and memory allocations) which we shall be much safer to avoid. [msb@chromium.org: edited commit message and modified to short-circuit panic_timeout < 0 instead of testing panic_timeout >= 0] Signed-off-by: Hugh Dickins Signed-off-by: Mandeep Singh Baines Cc: Dave Airlie Acked-by: David Rientjes Acked-by: Stéphane Marchesin Cc: Dave Young Signed-off-by: Andrew Morton --- drivers/gpu/drm/drm_fb_helper.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index 80fe39d98b0c..aada26f63dec 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -255,6 +255,13 @@ bool drm_fb_helper_force_kernel_mode(void) int drm_fb_helper_panic(struct notifier_block *n, unsigned long ununsed, void *panic_str) { + /* + * It's a waste of time and effort to switch back to text console + * if the kernel should reboot before panic messages can be seen. + */ + if (panic_timeout < 0) + return 0; + printk(KERN_ERR "panic occurred, switching back to text console\n"); return drm_fb_helper_force_kernel_mode(); } -- 2.39.5