Re: [PATCH] drm: avoid switching to text console if there is no panic timeout

[Dave Young]

On Tue, Oct 18, 2011 at 8:06 AM, Mandeep Singh Baines <msb@xxxxxxxxxxxx> wrote:
> From: Hugh Dickins <hughd@xxxxxxxxxxxx>
>
> 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.

There's one exception is use printk_delay

>
> Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
> [ Edited commit message and modified to short-circuit panic_timeout < 0
> Âinstead of testing panic_timeout >= 0. Â-Mandeep ]
> Signed-off-by: Mandeep Singh Baines <msb@xxxxxxxxxxxx>
> Cc: Dave Airlie <airlied@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> ---
> Âdrivers/gpu/drm/drm_fb_helper.c | Â Â7 +++++++
> Â1 files changed, 7 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index f7c6854..0e62c93 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -254,6 +254,13 @@ bool drm_fb_helper_force_kernel_mode(void)
> Âint drm_fb_helper_panic(struct notifier_block *n, unsigned long ununsed,
> Â Â Â Â Â Â Â Â Â Â Â Âvoid *panic_str)
> Â{
> + Â Â Â /*
> + Â Â Â Â* It's a waste of time and effort to switch back to text console
> + Â Â Â Â* if the kernel should reboot before panic messages can be seen.
> + Â Â Â Â*/
> + Â Â Â if (panic_timeout < 0)
> + Â Â Â Â Â Â Â return 0;
> +
> Â Â Â Âprintk(KERN_ERR "panic occurred, switching back to text console\n");
> Â Â Â Âreturn drm_fb_helper_force_kernel_mode();
> Â}
> --
> 1.7.3.1
>
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-- 
Regards
Dave
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