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

[Dave Young]

On Tue, Oct 18, 2011 at 10:19 AM, Dave Young <hidave.darkstar@xxxxxxxxx> wrote:
> 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

OTOH the complexity do exist also when timeout is set, IMHO it is worth

>
>>
>> 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
>



-- 
Regards
Dave
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