On 10/27/2014 06:26 AM, Finn Thain wrote: > Don't disable irqs when waiting for the ST DMA "lock"; its release may > require an interrupt. > > Introduce stdma_try_lock() for use in soft irq context. atari_scsi now tells > the SCSI mid-layer to defer queueing a command if the ST DMA lock is not > available, as per Michael's patch: > http://marc.info/?l=linux-m68k&m=139095335824863&w=2 > > The falcon_got_lock variable is race prone: we can't disable IRQs while > waiting to acquire the lock, so after acquiring it there must be some > interval during which falcon_got_lock remains false. Introduce > stdma_is_locked_by() to replace falcon_got_lock. > > The falcon_got_lock tests in the EH handlers are incorrect these days. It > can happen that an EH handler is called after a command completes normally. > Remove these checks along with falcon_got_lock. > > Also remove the complicated and racy fairness wait queues. If fairness is an > issue (when SCSI competes with IDE for the ST DMA interrupt), the solution > is likely to be a lower value for host->can_queue. > > Signed-off-by: Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx> Reviewed-by: Hannes Reinecke <hare@xxxxxxx> Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
