From: James Smart <jsmart2021@gmail.com>
Date: Tue, 12 Mar 2019 16:30:05 -0700
Subject: [PATCH] scsi: lpfc: Resolve irq-unsafe lockdep heirarchy warning in
lpfc_io_free
References: bsc#1136217,jsc#SLE-4722
Git-commit: 50e3f871fb20a9bb644743e2986e8f50f98a25bc
Patch-mainline: v5.2-rc1
A patch in the 12.2.0.0 set caused a new lockdep warning:
WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected
5.0.0-rc8-next-20190301-dbg+ #1 Not tainted
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&(&qp->io_buf_list_put_lock)->rlock);
local_irq_disable();
lock(&(&phba->hbalock)->rlock);
lock(&(&qp->io_buf_list_put_lock)->rlock);
<Interrupt>
lock(&(&phba->hbalock)->rlock);
see: https://www.spinics.net/lists/linux-scsi/msg128389.html
In summary, the new patch added taking the io_buf_list_put_lock while under
an irq-disabled hbalock. This created a lock heirarchy dependent upon irq
being disabled, and there are paths that take the io_buf_list_put_lock
without disabling irq.
Looking at the lpfc_io_free routine, which is where the new heirarchy was
introduced, there is no reason to be taking out the hbalock and raising
irq, as the functionality is replaced by the io_buf_list_xxx locks.
Resolve by removing the hbalock/irq calls in lpfc_io_free.
Fixes: 5e5b511d8bfa ("scsi: lpfc: Partition XRI buffer list across Hardware Queues")
Reported-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Dick Kennedy <dick.kennedy@broadcom.com>
Signed-off-by: James Smart <jsmart2021@gmail.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
drivers/scsi/lpfc/lpfc_init.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c
index b6112fc7aba8..0f030b3c5563 100644
--- a/drivers/scsi/lpfc/lpfc_init.c
+++ b/drivers/scsi/lpfc/lpfc_init.c
@@ -3611,8 +3611,6 @@ lpfc_io_free(struct lpfc_hba *phba)
struct lpfc_sli4_hdw_queue *qp;
int idx;
- spin_lock_irq(&phba->hbalock);
-
for (idx = 0; idx < phba->cfg_hdw_queue; idx++) {
qp = &phba->sli4_hba.hdwq[idx];
/* Release all the lpfc_nvme_bufs maintained by this host. */
@@ -3642,8 +3640,6 @@ lpfc_io_free(struct lpfc_hba *phba)
}
spin_unlock(&qp->io_buf_list_get_lock);
}
-
- spin_unlock_irq(&phba->hbalock);
}
/**
--
2.16.4