Messages in this thread | | | Date | Wed, 25 Sep 2013 10:13:01 -0400 | From | Steven Rostedt <> | Subject | Re: [Intel-gfx] BUG: sleeping function called from invalid context on 3.10.10-rt7 |
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On Wed, 25 Sep 2013 06:32:10 +0200 Mario Kleiner <mario.kleiner@tuebingen.mpg.de> wrote:
> But given the new situation, your proposal is great! If we push the > clock readouts into the get_scanoutpos routine, we can make this robust > without causing grief for the rt people and without the need for a new > separate lock for display regs in intel-kms. > > E.g., for intel-kms: > > i915_get_crtc_scanoutpos(..., ktime_t *stime, ktime_t *etime) > { > ... > spin_lock_irqsave(...uncore.lock); > preempt_disable(); > *stime = ktime_get(); > position = __raw_i915_read32(dev_priv, PIPEDSL(pipe)); > *etime = ktime_get(); > preempt_enable(); > spin_unlock_irqrestore(...uncore.lock) > ... > } > > With your patchset to reduce the amount of register reads needed in that > function, and given that forcewake handling isn't needed for these > registers, this should make it robust again and wouldn't need new locks. > > Unless ktime_get is also a bad thing to do in a preempt disabled section?
ktime_get() works fine in preempt_disable sections, although it may add some latencies, but you shouldn't need to worry about it.
I like this solution the best too, but if it does go in, I would ask to send us the patch for adding the preempt_disable() and we can add the preempt_disable_rt() to it. Why make mainline have a little more overhead?
-- Steve
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