From: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Date: Mon, 23 Apr 2018 14:37:53 +0300
Subject: drm/i915: Use ktime on wait_for
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Git-commit: 6de3b1f26d1e8adb53d97835400c541ce50155e5
Patch-mainline: v4.17-rc3
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166
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 <imre.deak@intel.com>
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@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20180423113754.28424-1-mika.kuoppala@linux.intel.com
(cherry picked from commit 3085982c6b45d7d22f76e3aa018affbc143a7370)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
drivers/gpu/drm/i915/intel_drv.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- 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; \