diff mbox series

[02/30] lpfc: Resolve irq-unsafe lockdep heirarchy warning in lpfc_io_free

Message ID 20190312233033.32670-3-jsmart2021@gmail.com (mailing list archive)
State Accepted
Headers show
Series lpfc updates for 12.2.0.1 | expand

Commit Message

James Smart March 12, 2019, 11:30 p.m. UTC 
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>
---
 drivers/scsi/lpfc/lpfc_init.c | 4 ----
 1 file changed, 4 deletions(-)
diff mbox series

Patch

diff --git a/drivers/scsi/lpfc/lpfc_init.c b/drivers/scsi/lpfc/lpfc_init.c
index 707dbe7a8d15..3e9cc06c3cff 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);
 }
 
 /**