From: Mika Kuoppala Date: Mon, 23 Apr 2018 11:37:53 +0000 (+0300) Subject: drm/i915: Use ktime on wait_for X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=3085982c6b45d7d22f76e3aa018affbc143a7370;p=linux.git drm/i915: Use ktime on wait_for 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. Discard jiffies and change to ktime to detect timeouts. v2: added bugzilla entry (Imre), added stable (Chris) Reported-by: Imre Deak References: https://lkml.org/lkml/2018/4/18/798 [1] Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105771 Cc: Imre Deak Cc: Chris Wilson Cc: Ville Syrjälä Cc: Signed-off-by: Mika Kuoppala Reviewed-by: Chris Wilson Link: https://patchwork.freedesktop.org/patch/msgid/20180423113754.28424-1-mika.kuoppala@linux.intel.com --- diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h index 44ed248f1fe9d..33ff2638c92bb 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; \