| Message ID | 1386664513-2972-1-git-send-email-mika.kuoppala@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Dec 10, 2013 at 10:35:13AM +0200, Mika Kuoppala wrote: > Commit 094f9a54e355 ("drm/i915: Fix __wait_seqno to use true infinite > timeouts") added support for __wait_seqno to detect missing interrupts and > go around them by polling. As there is also timeout detection in > __wait_seqno, the polling and timeout detection were done with the same > timer. > > When there has been missed interrupts and polling is needed, the timer is > set to trigger in (now + 1) jiffies in future, instead of the caller > specified timeout. > > Now when io_schedule() returns, we calculate the jiffies left to timeout > using the timer expiration value. As the current jiffies is now bound to be > always equal or greater than the expiration value, the timeout_jiffies will > become zero or negative and we return -ETIME to caller even tho the > timeout was never reached. > > Fix this by decoupling timeout calculation from timer expiration. > > v2: Commit message with some sense in it (Chris Wilson) > > v3: add parenthesis on timeout_expire calculation > > Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com> > --- > drivers/gpu/drm/i915/i915_gem.c | 14 ++++++-------- > 1 file changed, 6 insertions(+), 8 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c > index 92149bc..71df9be 100644 > --- a/drivers/gpu/drm/i915/i915_gem.c > +++ b/drivers/gpu/drm/i915/i915_gem.c > @@ -1017,7 +1017,7 @@ static int __wait_seqno(struct intel_ring_buffer *ring, u32 seqno, > drm_i915_private_t *dev_priv = ring->dev->dev_private; > struct timespec before, now; > DEFINE_WAIT(wait); > - long timeout_jiffies; > + unsigned long timeout_expire; > int ret; > > WARN(dev_priv->pc8.irqs_disabled, "IRQs disabled\n"); > @@ -1025,7 +1025,7 @@ static int __wait_seqno(struct intel_ring_buffer *ring, u32 seqno, > if (i915_seqno_passed(ring->get_seqno(ring, true), seqno)) > return 0; > > - timeout_jiffies = timeout ? timespec_to_jiffies_timeout(timeout) : 1; > + timeout_expire = jiffies + (timeout ? timespec_to_jiffies_timeout(timeout) : 1); I would jiggle this slightly to not read jiffies if timeout == NULL, i.e. timeout_expire = timeout ? jiffies + timespec_to_jiffies_timeout(timeout) : 0; (Hmm, we should be keeping these helpers separate from i915_drv.h.). As we only set timeout_expire here if !timeout to keep the compiler quiet. -Chris
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 92149bc..71df9be 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -1017,7 +1017,7 @@ static int __wait_seqno(struct intel_ring_buffer *ring, u32 seqno, drm_i915_private_t *dev_priv = ring->dev->dev_private; struct timespec before, now; DEFINE_WAIT(wait); - long timeout_jiffies; + unsigned long timeout_expire; int ret; WARN(dev_priv->pc8.irqs_disabled, "IRQs disabled\n"); @@ -1025,7 +1025,7 @@ static int __wait_seqno(struct intel_ring_buffer *ring, u32 seqno, if (i915_seqno_passed(ring->get_seqno(ring, true), seqno)) return 0; - timeout_jiffies = timeout ? timespec_to_jiffies_timeout(timeout) : 1; + timeout_expire = jiffies + (timeout ? timespec_to_jiffies_timeout(timeout) : 1); if (dev_priv->info->gen >= 6 && can_wait_boost(file_priv)) { gen6_rps_boost(dev_priv); @@ -1044,7 +1044,6 @@ static int __wait_seqno(struct intel_ring_buffer *ring, u32 seqno, getrawmonotonic(&before); for (;;) { struct timer_list timer; - unsigned long expire; prepare_to_wait(&ring->irq_queue, &wait, interruptible ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE); @@ -1070,23 +1069,22 @@ static int __wait_seqno(struct intel_ring_buffer *ring, u32 seqno, break; } - if (timeout_jiffies <= 0) { + if (timeout && time_after_eq(jiffies, timeout_expire)) { ret = -ETIME; break; } timer.function = NULL; if (timeout || missed_irq(dev_priv, ring)) { + unsigned long expire; + setup_timer_on_stack(&timer, fake_irq, (unsigned long)current); - expire = jiffies + (missed_irq(dev_priv, ring) ? 1: timeout_jiffies); + expire = missed_irq(dev_priv, ring) ? jiffies + 1 : timeout_expire; mod_timer(&timer, expire); } io_schedule(); - if (timeout) - timeout_jiffies = expire - jiffies; - if (timer.function) { del_singleshot_timer_sync(&timer); destroy_timer_on_stack(&timer);
Commit 094f9a54e355 ("drm/i915: Fix __wait_seqno to use true infinite timeouts") added support for __wait_seqno to detect missing interrupts and go around them by polling. As there is also timeout detection in __wait_seqno, the polling and timeout detection were done with the same timer. When there has been missed interrupts and polling is needed, the timer is set to trigger in (now + 1) jiffies in future, instead of the caller specified timeout. Now when io_schedule() returns, we calculate the jiffies left to timeout using the timer expiration value. As the current jiffies is now bound to be always equal or greater than the expiration value, the timeout_jiffies will become zero or negative and we return -ETIME to caller even tho the timeout was never reached. Fix this by decoupling timeout calculation from timer expiration. v2: Commit message with some sense in it (Chris Wilson) v3: add parenthesis on timeout_expire calculation Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com> --- drivers/gpu/drm/i915/i915_gem.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-)