[PATCH 06/26] lpfc: Fix SCSI I/O completion and abort handler deadlock

[James Smart <jsmart2021@gmail.com>]

During stress I/O tests with 500+ vports, hard LOCKUP call traces are
observed.

CPU A:
 native_queued_spin_lock_slowpath+0x192
 _raw_spin_lock_irqsave+0x32
 lpfc_handle_fcp_err+0x4c6
 lpfc_fcp_io_cmd_wqe_cmpl+0x964
 lpfc_sli4_fp_handle_cqe+0x266
 __lpfc_sli4_process_cq+0x105
 __lpfc_sli4_hba_process_cq+0x3c
 lpfc_cq_poll_hdler+0x16
 irq_poll_softirq+0x76
 __softirqentry_text_start+0xe4
 irq_exit+0xf7
 do_IRQ+0x7f

CPU B:
 native_queued_spin_lock_slowpath+0x5b
 _raw_spin_lock+0x1c
 lpfc_abort_handler+0x13e
 scmd_eh_abort_handler+0x85
 process_one_work+0x1a7
 worker_thread+0x30
 kthread+0x112
 ret_from_fork+0x1f

Diagram of lockup:

CPUA                            CPUB
----                            ----
lpfc_cmd->buf_lock
                            phba->hbalock
                            lpfc_cmd->buf_lock
phba->hbalock

Fix by reordering the taking of the lpfc_cmd->buf_lock and phba->hbalock
in lpfc_abort_handler routine so that it tries to take the
lpfc_cmd->buf_lock first before phba->hbalock.

Co-developed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
---
 drivers/scsi/lpfc/lpfc_scsi.c | 33 +++++++++++++++------------------
 1 file changed, 15 insertions(+), 18 deletions(-)

diff --git a/drivers/scsi/lpfc/lpfc_scsi.c b/drivers/scsi/lpfc/lpfc_scsi.c
index ae340850d94f..c3daf7a3e123 100644
--- a/drivers/scsi/lpfc/lpfc_scsi.c
+++ b/drivers/scsi/lpfc/lpfc_scsi.c
@@ -5865,25 +5865,25 @@ lpfc_abort_handler(struct scsi_cmnd *cmnd)
 	if (!lpfc_cmd)
 		return ret;
 
-	spin_lock_irqsave(&phba->hbalock, flags);
+	/* Guard against IO completion being called at same time */
+	spin_lock_irqsave(&lpfc_cmd->buf_lock, flags);
+
+	spin_lock(&phba->hbalock);
 	/* driver queued commands are in process of being flushed */
 	if (phba->hba_flag & HBA_IOQ_FLUSH) {
 		lpfc_printf_vlog(vport, KERN_WARNING, LOG_FCP,
 			"3168 SCSI Layer abort requested I/O has been "
 			"flushed by LLD.\n");
 		ret = FAILED;
-		goto out_unlock;
+		goto out_unlock_hba;
 	}
 
-	/* Guard against IO completion being called at same time */
-	spin_lock(&lpfc_cmd->buf_lock);
-
 	if (!lpfc_cmd->pCmd) {
 		lpfc_printf_vlog(vport, KERN_WARNING, LOG_FCP,
 			 "2873 SCSI Layer I/O Abort Request IO CMPL Status "
 			 "x%x ID %d LUN %llu\n",
 			 SUCCESS, cmnd->device->id, cmnd->device->lun);
-		goto out_unlock_buf;
+		goto out_unlock_hba;
 	}
 
 	iocb = &lpfc_cmd->cur_iocbq;
@@ -5891,7 +5891,7 @@ lpfc_abort_handler(struct scsi_cmnd *cmnd)
 		pring_s4 = phba->sli4_hba.hdwq[iocb->hba_wqidx].io_wq->pring;
 		if (!pring_s4) {
 			ret = FAILED;
-			goto out_unlock_buf;
+			goto out_unlock_hba;
 		}
 		spin_lock(&pring_s4->ring_lock);
 	}
@@ -5924,8 +5924,8 @@ lpfc_abort_handler(struct scsi_cmnd *cmnd)
 			 "3389 SCSI Layer I/O Abort Request is pending\n");
 		if (phba->sli_rev == LPFC_SLI_REV4)
 			spin_unlock(&pring_s4->ring_lock);
-		spin_unlock(&lpfc_cmd->buf_lock);
-		spin_unlock_irqrestore(&phba->hbalock, flags);
+		spin_unlock(&phba->hbalock);
+		spin_unlock_irqrestore(&lpfc_cmd->buf_lock, flags);
 		goto wait_for_cmpl;
 	}
 
@@ -5946,15 +5946,13 @@ lpfc_abort_handler(struct scsi_cmnd *cmnd)
 	if (ret_val != IOCB_SUCCESS) {
 		/* Indicate the IO is not being aborted by the driver. */
 		lpfc_cmd->waitq = NULL;
-		spin_unlock(&lpfc_cmd->buf_lock);
-		spin_unlock_irqrestore(&phba->hbalock, flags);
 		ret = FAILED;
-		goto out;
+		goto out_unlock_hba;
 	}
 
 	/* no longer need the lock after this point */
-	spin_unlock(&lpfc_cmd->buf_lock);
-	spin_unlock_irqrestore(&phba->hbalock, flags);
+	spin_unlock(&phba->hbalock);
+	spin_unlock_irqrestore(&lpfc_cmd->buf_lock, flags);
 
 	if (phba->cfg_poll & DISABLE_FCP_RING_INT)
 		lpfc_sli_handle_fast_ring_event(phba,
@@ -5989,10 +5987,9 @@ lpfc_abort_handler(struct scsi_cmnd *cmnd)
 out_unlock_ring:
 	if (phba->sli_rev == LPFC_SLI_REV4)
 		spin_unlock(&pring_s4->ring_lock);
-out_unlock_buf:
-	spin_unlock(&lpfc_cmd->buf_lock);
-out_unlock:
-	spin_unlock_irqrestore(&phba->hbalock, flags);
+out_unlock_hba:
+	spin_unlock(&phba->hbalock);
+	spin_unlock_irqrestore(&lpfc_cmd->buf_lock, flags);
 out:
 	lpfc_printf_vlog(vport, KERN_WARNING, LOG_FCP,
 			 "0749 SCSI Layer I/O Abort Request Status x%x ID %d "
-- 
2.26.2