[Intel-gfx] [PATCH v2 1/3] drm: Add support for panic message output

[John Ogness]

On 2019-03-14, John Ogness <john.ogness at linutronix.de> wrote:
> On 2019-03-14, Daniel Vetter <daniel at ffwll.ch> wrote:
>> That's why we came up with the trylock + immediate bail out design if
>> that fails. Plus really only render the oops int whatever is the
>> current display buffer, so that we don't have to do any hw
>> programming at all.
>
> I think this is your best option. The real work will be identifying
> any/all spin locking that currently exists. For all of those, the code
> needs to change to:
>
> 1. trylock if oops_in_progress, otherwise spinlock

On second thought, you shouldn't use oops_in_progress. It would be
better if DRM had its own flag to signify that it is currently being
used in kmsg_dump context.

> 2. if trylock fails, the code must have a sane failure
>
> The 2nd point will be the difficult one. For example, you may have
> functions without a return value taking spinlocks. But now those
> functions could fail.

John Ogness