scsi: ibmvscsi: fix tripping of blk_mq_run_hw_queue WARN_ON
After a successful SRP login response we call scsi_unblock_requests() to kick any pending IOs. The callback to process this SRP response happens in a tasklet and therefore is in softirq context. The result of such is that when blk-mq is enabled, it is no longer safe to call scsi_unblock_requests() from this context. The result of duing so triggers the following WARN_ON splat in dmesg after a host reset or CRQ reenablement. WARNING: CPU: 0 PID: 0 at block/blk-mq.c:1375 __blk_mq_run_hw_queue+0x120/0x180 Modules linked in: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.0.0-rc8 #4 NIP [c0000000009771e0] __blk_mq_run_hw_queue+0x120/0x180 LR [c000000000977484] __blk_mq_delay_run_hw_queue+0x244/0x250 Call Trace: __blk_mq_delay_run_hw_queue+0x244/0x250 blk_mq_run_hw_queue+0x8c/0x1c0 blk_mq_run_hw_queues+0x60/0x90 scsi_run_queue+0x1e4/0x3b0 scsi_run_host_queues+0x48/0x80 login_rsp+0xb0/0x100 ibmvscsi_handle_crq+0x30c/0x3e0 ibmvscsi_task+0x54/0xe0 tasklet_action_common.isra.3+0xc4/0x1a0 __do_softirq+0x174/0x3f4 irq_exit+0xf0/0x120 __do_irq+0xb0/0x210 call_do_irq+0x14/0x24 do_IRQ+0x9c/0x130 hardware_interrupt_common+0x14c/0x150 This patch fixes the issue by introducing a new host action for unblocking the scsi requests in our seperate work thread. Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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@ -1179,7 +1179,8 @@ static void login_rsp(struct srp_event_struct *evt_struct)
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be32_to_cpu(evt_struct->xfer_iu->srp.login_rsp.req_lim_delta));
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be32_to_cpu(evt_struct->xfer_iu->srp.login_rsp.req_lim_delta));
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/* If we had any pending I/Os, kick them */
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/* If we had any pending I/Os, kick them */
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scsi_unblock_requests(hostdata->host);
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hostdata->action = IBMVSCSI_HOST_ACTION_UNBLOCK;
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wake_up(&hostdata->work_wait_q);
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}
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}
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/**
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/**
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@ -2123,6 +2124,7 @@ static void ibmvscsi_do_work(struct ibmvscsi_host_data *hostdata)
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spin_lock_irqsave(hostdata->host->host_lock, flags);
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spin_lock_irqsave(hostdata->host->host_lock, flags);
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switch (hostdata->action) {
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switch (hostdata->action) {
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case IBMVSCSI_HOST_ACTION_NONE:
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case IBMVSCSI_HOST_ACTION_NONE:
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case IBMVSCSI_HOST_ACTION_UNBLOCK:
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break;
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break;
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case IBMVSCSI_HOST_ACTION_RESET:
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case IBMVSCSI_HOST_ACTION_RESET:
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spin_unlock_irqrestore(hostdata->host->host_lock, flags);
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spin_unlock_irqrestore(hostdata->host->host_lock, flags);
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@ -2164,6 +2166,7 @@ static int __ibmvscsi_work_to_do(struct ibmvscsi_host_data *hostdata)
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return 0;
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return 0;
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case IBMVSCSI_HOST_ACTION_RESET:
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case IBMVSCSI_HOST_ACTION_RESET:
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case IBMVSCSI_HOST_ACTION_REENABLE:
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case IBMVSCSI_HOST_ACTION_REENABLE:
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case IBMVSCSI_HOST_ACTION_UNBLOCK:
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default:
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default:
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break;
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break;
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}
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}
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@ -92,6 +92,7 @@ enum ibmvscsi_host_action {
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IBMVSCSI_HOST_ACTION_NONE = 0,
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IBMVSCSI_HOST_ACTION_NONE = 0,
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IBMVSCSI_HOST_ACTION_RESET,
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IBMVSCSI_HOST_ACTION_RESET,
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IBMVSCSI_HOST_ACTION_REENABLE,
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IBMVSCSI_HOST_ACTION_REENABLE,
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IBMVSCSI_HOST_ACTION_UNBLOCK,
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};
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};
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/* all driver data associated with a host adapter */
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/* all driver data associated with a host adapter */
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