On Mon, Apr 23, 2018 at 4:37 AM, Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx> wrote: > We use jiffies to determine when wait expires. However > Imre did find out that jiffies can and will do a >1 > increments on certain situations [1]. When this happens > in a wait_for loop, we return timeout errorneously > much earlier than what the real wallclock would say. > > We can't afford our waits to timeout prematurely. Isn't this also the reason why we have *_to_jiffies_timeout() family of functions? Should those be converted as well? Lucas De Marchi > Discard jiffies and change to ktime to detect timeouts. > > v2: added bugzilla entry (Imre), added stable (Chris) > > Reported-by: Imre Deak <imre.deak@xxxxxxxxx> > References: https://lkml.org/lkml/2018/4/18/798 [1] > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105771 > Cc: Imre Deak <imre.deak@xxxxxxxxx> > Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> > Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx> > Reviewed-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_drv.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h > index 44ed248f1fe9..33ff2638c92b 100644 > --- a/drivers/gpu/drm/i915/intel_drv.h > +++ b/drivers/gpu/drm/i915/intel_drv.h > @@ -49,12 +49,12 @@ > * check the condition before the timeout. > */ > #define __wait_for(OP, COND, US, Wmin, Wmax) ({ \ > - unsigned long timeout__ = jiffies + usecs_to_jiffies(US) + 1; \ > + const ktime_t end__ = ktime_add_ns(ktime_get_raw(), 1000ll * (US)); \ > long wait__ = (Wmin); /* recommended min for usleep is 10 us */ \ > int ret__; \ > might_sleep(); \ > for (;;) { \ > - bool expired__ = time_after(jiffies, timeout__); \ > + const bool expired__ = ktime_after(ktime_get_raw(), end__); \ > OP; \ > if (COND) { \ > ret__ = 0; \ > -- > 2.14.1 > > _______________________________________________ > Intel-gfx mailing list > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/intel-gfx -- Lucas De Marchi _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
