On 10/6/19 4:45 AM, Ming Lei wrote: > Most of blk-mq drivers depend on managed IRQ's auto-affinity to setup > up queue mapping. Thomas mentioned the following point[1]: > > " > That was the constraint of managed interrupts from the very beginning: > > The driver/subsystem has to quiesce the interrupt line and the associated > queue _before_ it gets shutdown in CPU unplug and not fiddle with it > until it's restarted by the core when the CPU is plugged in again. > " > > However, current blk-mq implementation doesn't quiesce hw queue before > the last CPU in the hctx is shutdown. Even worse, CPUHP_BLK_MQ_DEAD is > one cpuhp state handled after the CPU is down, so there isn't any chance > to quiesce hctx for blk-mq wrt. CPU hotplug. > > Add new cpuhp state of CPUHP_AP_BLK_MQ_ONLINE for blk-mq to stop queues > and wait for completion of in-flight requests. > > [1] https://lore.kernel.org/linux-block/alpine.DEB.2.21.1904051331270.1802@xxxxxxxxxxxxxxxxxxxxxxx/ > > Cc: Bart Van Assche <bvanassche@xxxxxxx> > Cc: Hannes Reinecke <hare@xxxxxxxx> > Cc: Christoph Hellwig <hch@xxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: Keith Busch <keith.busch@xxxxxxxxx> > Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> > --- > block/blk-mq-tag.c | 2 +- > block/blk-mq-tag.h | 2 ++ > block/blk-mq.c | 65 ++++++++++++++++++++++++++++++++++++++ > include/linux/blk-mq.h | 1 + > include/linux/cpuhotplug.h | 1 + > 5 files changed, 70 insertions(+), 1 deletion(-) > I really don't like the zillions of 'XXX_in_flight()' helper in blk-mq; blk_mq_queue_inflight(), blk_mq_in_flight(), blk_mq_in_flight_rw() et al. Can't you implement your one on top of the already existing? Otherwise: Reviewed-by: Hannes Reinecke <hare@xxxxxxxx> Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 247165 (AG München), GF: Felix Imendörffer
