The busywait in __i915_spin_request() does not respect pending signals
and so may consume the entire timeslice for the task instead of
returning to userspace to handle the signal.
Fixes regression from
commit 2def4ad99befa25775dd2f714fdd4d92faec6e34 [v4.2]
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date: Tue Apr 7 16:20:41 2015 +0100
drm/i915: Optimistically spin for the request completion
Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Jens Axboe <axboe at kernel.dk>
Cc; "Rogozhkin, Dmitry V" <dmitry.v.rogozhkin at intel.com>
Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
Cc: Eero Tamminen <eero.t.tamminen at intel.com>
Cc: "Rantala, Valtteri" <valtteri.rantala at intel.com>
Cc: stable at kernel.vger.org
---
drivers/gpu/drm/i915/i915_gem.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 5cf4a1998273..740530c571d1 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1146,7 +1146,7 @@ static bool missed_irq(struct drm_i915_private *dev_priv,
return test_bit(ring->id, &dev_priv->gpu_error.missed_irq_rings);
}
-static int __i915_spin_request(struct drm_i915_gem_request *req)
+static int __i915_spin_request(struct drm_i915_gem_request *req, int state)
{
unsigned long timeout;
@@ -1158,6 +1158,9 @@ static int __i915_spin_request(struct
drm_i915_gem_request *req)
if (i915_gem_request_completed(req, true))
return 0;
+ if (signal_pending_state(state, current))
+ break;
+
if (time_after_eq(jiffies, timeout))
break;
@@ -1197,6 +1200,7 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
struct drm_i915_private *dev_priv = dev->dev_private;
const bool irq_test_in_progress =
ACCESS_ONCE(dev_priv->gpu_error.test_irq_rings) &
intel_ring_flag(ring);
+ int state = interruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE;
DEFINE_WAIT(wait);
unsigned long timeout_expire;
s64 before, now;
@@ -1221,7 +1225,7 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
before = ktime_get_raw_ns();
/* Optimistic spin for the next jiffie before touching IRQs */
- ret = __i915_spin_request(req);
+ ret = __i915_spin_request(req, state);
if (ret == 0)
goto out;
@@ -1233,8 +1237,7 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
for (;;) {
struct timer_list timer;
- prepare_to_wait(&ring->irq_queue, &wait,
- interruptible ? TASK_INTERRUPTIBLE :
TASK_UNINTERRUPTIBLE);
+ prepare_to_wait(&ring->irq_queue, &wait, state);
/* We need to check whether any gpu reset happened in between
* the caller grabbing the seqno and now ... */
@@ -1252,7 +1255,7 @@ int __i915_wait_request(struct drm_i915_gem_request *req,
break;
}
- if (interruptible && signal_pending(current)) {
+ if (signal_pending_state(state, current)) {
ret = -ERESTARTSYS;
break;
}
--
2.6.2
