Re: [PATCH 1/2] drm/i915: compute wait_ioctl timeout correctly

Chris Wilson
2014-11-28T10:09:47Z

On Fri, Nov 28, 2014 at 10:29:54AM +0100, Daniel Vetter wrote:
> We've lost the +1 required for correct timeouts in
>
> commit 5ed0bdf21a85d78e04f89f15ccf227562177cbd9
> Author: Thomas Gleixner <tglx@linutronix.de>
> Date: Wed Jul 16 21:05:06 2014 +0000
>
> drm: i915: Use nsec based interfaces
>
> Use ktime_get_raw_ns() and get rid of the back and forth timespec
> conversions.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Signed-off-by: John Stultz <john.stultz@linaro.org>
>
> So fix this up by reinstating our handrolled _timeout function. While
> at it bother with handling MAX_JIFFIES.
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=82749
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: John Stultz <john.stultz@linaro.org>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
> drivers/gpu/drm/i915/i915_drv.h | 10 ++++++++++
> drivers/gpu/drm/i915/i915_gem.c | 3 ++-
> 2 files changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 02b3cb32c8a6..caae337c0199 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -3030,6 +3030,16 @@ static inline unsigned long msecs_to_jiffies_timeout(const unsigned int m)
> return min_t(unsigned long, MAX_JIFFY_OFFSET, j + 1);
> }
>
> +static inline unsigned long nsecs_to_jiffies_timeout(const u64 m)
> +{
> + unsigned long j = nsecs_to_jiffies(m);

Still u64 here.
> +
> + if (m > (u64)jiffies_to_usecs(MAX_JIFFY_OFFSET) * 1000)
> + return MAX_JIFFY_OFFSET;
> +
> + return min_t(unsigned long, MAX_JIFFY_OFFSET, j + 1);

These two tests are doing identical jobs, so the first one is redundant
so long as we maintain u64 until the final check?
-Chris

--
Chris Wilson, Intel Open Source Technology Centre