[Intel-gfx] [PATCH v2] drm/i915: Handle full s64 precision for wait-ioctl

[Joonas Lahtinen]

On Fri, 2017-08-11 at 11:57 +0100, Chris Wilson wrote:
> The wait-ioctl is optionally supplied a timeout with nanosecond
> precision in a s64 field. We use nsecs_to_jiffies64() to convert that
> into the jiffies consumed by the scheduler, but internally
> nsecs_to_jiffies64() does not guard against overflow (as it's purpose is
> for use by the scheduler and not drivers!). So we must guard against the
> overflow ourselves, and in the process note that we may then return
> much earlier than the timeout selected by the user, so don't report
> ETIME unless we do hit the timeout. (Woe betold us though if the user
> waits for a year (32bit) and the request is still not complete!)
> 
> v2: Refine overflow detection (to not include an overffow itself)
> 
> Reported-by: Jason Ekstrand <jason.ekstrand at intel.com>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>

Reviewed-by: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>

Regards, Joonas
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation