On Thu, Apr 02, 2015 at 07:21:40PM +0530, deepa...@linux.intel.com wrote: > From: Deepak S <deepa...@linux.intel.com> > > Sometimes, i915 might call _wait_for when irq is disabled. > If the cpu is the main cpu to process jiffies, jiffies > wouldn't be increased as this cpu disables irq. Then, > time_after(jiffies, timeout__) becomes meaningless. If > gunit doesn't work now, kernel wouldn't exit as the timeout > doesn't work. > > The patch fixes it by using sched_clock instead of jiffies.
sched_clock() requires irq disabled, or at least so the header claims, at the very least it would require preemption disabled - definitely not for our general waits of many ms. Also local_clock() would seem to be the right choice in these tight loops. I think you want a specialised macro (if any) that is very aware of the constraints it is running under. I would hope we never have to busy spin with interrupts disabled. And so I want such code that does to blatantly obvious and scrutinised carefully. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx
