[SCSI] qla2xxx: fix potential deadlock on ha->hardware_lock

Lockdep reports:

=== [ cut here ] ===
 =========================================================
 [ INFO: possible irq lock inversion dependency detected ]
 3.6.0-0.0.0.28.36b5ec9-default #1 Not tainted
 ---------------------------------------------------------
 qla2xxx_1_dpc/368 just changed the state of lock:
  (&(&ha->vport_slock)->rlock){+.....}, at: [<ffffffffa009b377>] qla2x00_configure_hba+0x197/0x3c0 [qla2xxx]
 but this lock was taken by another, HARDIRQ-safe lock in the past:
  (&(&ha->hardware_lock)->rlock){-.....}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this:
 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&(&ha->vport_slock)->rlock);
                               local_irq_disable();
                               lock(&(&ha->hardware_lock)->rlock);
                               lock(&(&ha->vport_slock)->rlock);
  <Interrupt>
    lock(&(&ha->hardware_lock)->rlock);
=== [ cut here ] ===

Fix the potential deadlock by disabling IRQs while holding ha->vport_slock.

Reported-and-tested-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Saurav Kashyap <saurav.kashyap@qlogic.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/scsi/qla2xxx/qla_init.c b/drivers/scsi/qla2xxx/qla_init.c
index 799a58bb9859..48fca47384b7 100644
--- a/drivers/scsi/qla2xxx/qla_init.c
+++ b/drivers/scsi/qla2xxx/qla_init.c
@@ -2080,6 +2080,7 @@ qla2x00_configure_hba(scsi_qla_host_t *vha)
         uint8_t       domain;
         char            connect_type[22];
         struct qla_hw_data *ha = vha->hw;
+        unsigned long flags;
 
         /* Get host addresses. */
         rval = qla2x00_get_adapter_id(vha,
@@ -2154,9 +2155,9 @@ qla2x00_configure_hba(scsi_qla_host_t *vha)
         vha->d_id.b.area = area;
         vha->d_id.b.al_pa = al_pa;
 
-        spin_lock(&ha->vport_slock);
+        spin_lock_irqsave(&ha->vport_slock, flags);
         qlt_update_vp_map(vha, SET_AL_PA);
-        spin_unlock(&ha->vport_slock);
+        spin_unlock_irqrestore(&ha->vport_slock, flags);
 
         if (!vha->flags.init_done)
                 ql_log(ql_log_info, vha, 0x2010,