[Intel-gfx] [PATCH] drm/i915: irq handlers don't need interrupt-safe spinlocks

[Paulo Zanoni]

2013/6/27 Daniel Vetter <daniel.vetter at ffwll.ch>:
> On Thu, Jun 27, 2013 at 11:14 PM, Paulo Zanoni <przanoni at gmail.com> wrote:
>> 2013/6/25 Daniel Vetter <daniel.vetter at ffwll.ch>:
>>> Since we only have one interrupt handler and interrupt handlers are
>>> non-reentrant.
>>>
>>> To drive the point really home give them all an _irq_handler suffix.
>>
>> Could we also add WARN(!in_irq()) or something equivalent for better
>> protection? Big backtraces are a nice way to discover we did something
>> wrong.
>
> Lockdep checks hard/soft irq context constraints and will scream
> horribly into dmesg if we get it wrong. So I don't think a in_irq
> warning will add any value. Aside: hard/softirq isn't the only special
> context lockdep checks for, it also checks for memory allocations,
> e.g. if you hold a lock while calling kmalloc and your shrinker needs
> the same locks it'll scream. That's why we have all the GFP_NORETRY
> stuff when allocating memory and the trylock in the shrinker.

Ok then. Looks like I forgot the stamp: Reviewed-by: Paulo Zanoni
<paulo.r.zanoni at intel.com>

> -Daniel
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch



-- 
Paulo Zanoni