On Fri, Oct 28, 2016 at 11:49:34AM +0100, Tvrtko Ursulin wrote: > > > On 28/10/16 11:42, Chris Wilson wrote: > >On Fri, Oct 28, 2016 at 11:27:43AM +0100, Tvrtko Ursulin wrote: > >> > >> > >>On 28/10/16 11:10, Chris Wilson wrote: > >>>On Fri, Oct 28, 2016 at 10:42:22AM +0100, Tvrtko Ursulin wrote: > >>>> > >>>> > >>>>On 27/10/16 17:10, Chris Wilson wrote: > >>>>>The breadcrumbs are about to be used from within IRQ context sections, > >>>>>therefore we need to employ the irqsafe spinlock variants. > >>>>> > >>>>>(This is split out of the defer global seqno allocation patch due to > >>>>>realisation that we need a more complete conversion if we want to defer > >>>>>request submission even further.) > >>> > >>>[snip] > >>> > >>>>Assuming I got the above right and you agree to change it: > >>> > >>>You made me go and reduce them to _bh as appropriate anyway!!! > >> > >>Hm, but can't enable signalling be called with irqs disabled when > >>fences are exported? > > > >Yes, but that supercedes the spin_lock_bh, so we can just call > >spin_lock() in enabling_signaling as we can assert that we will always > >be called with irqs disabled here (due to spin_lock_irqsafe(fence->lock) > >in the callpath). > > But as long as the b->lock is taken in the irqs disabled section > somewhere, other callers like signaller thread, debugfs, etc, cannot > just take it with _bh. Lockdep doesn't complain, if we take spin_lock(b->lock) under irq inside our tasklet (enable_signaling) so long as we use spin_lock_bh() elsewhere. -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
