On Fri, 2017-07-28 at 08:25 -0600, Jens Axboe wrote: > On 07/28/2017 12:19 AM, Michael Ellerman wrote: > > OK, so the resolution is "fix it in IPR" ? > > I'll leave that to the SCSI crew. But at least one bug is in IPR, if you > look at the call trace: > > - timer function triggers, runs ipr_reset_timer_done(), which grabs the > host lock AND disables interrupts. > - further down in the call path, ipr_ioa_bringdown_done() uncondtionally > enables interrupts: > > spin_unlock_irq(ioa_cfg->host->host_lock); > scsi_unblock_requests(ioa_cfg->host); > spin_lock_irq(ioa_cfg->host->host_lock); > > And the call to scsi_unblock_requests() is the one that ultimately runs > the queue. The IRQ issue aside here, scsi_unblock_requests() could run > the queue async, and we could retain the normal sync run otherwise. > > Can you try the below fix? Should be more palatable than the previous > one. Brian, maybe you can take a look at the IRQ issue mentioned above? > > [ ... ] Hello Jens, Are there other block drivers that can call blk_mq_start_hw_queues() from interrupt context? I'm currently working on converting the skd driver (drivers/block/skd_main.c) from a single queue block driver into a scsi-mq driver. The skd driver calls blk_start_queue() from interrupt context. As we know it is not safe to call blk_mq_start_hw_queues() from interrupt context. Can you recommend me how I should proceed: should I implement a solution in the skd driver or should perhaps the blk-mq core be modified? Thanks, Bart.
