[SCSI] qla2xxx: Defer enablement of RISC interrupts until ISP initialization completes.

Josip Rodin noted
(http://article.gmane.org/gmane.linux.ports.sparc/10152) the
driver oopsing during registration of an rport to the
FC-transport layer with a backtrace indicating a dereferencing of
an shost->shost_data equal to NULL.  David Miller identified a
small window in driver logic where this could happen:

    > Look at how the driver registers the IRQ handler before the host has
    > been registered with the SCSI layer.
    >
    > That leads to a window of time where the shost hasn't been setup
    > fully, yet ISRs can come in and trigger DPC thread events, such as
    > loop resyncs, which expect the transport area to be setup.
    >
    > But it won't be setup, because scsi_add_host() hasn't finished yet.
    >
    > Note that in Josip's crash log, we don't even see the
    >
    >         qla_printk(KERN_INFO, ha, "\n"
    >             " QLogic Fibre Channel HBA Driver: %s\n"
    >             "  QLogic %s - %s\n"
    >             "  ISP%04X: %s @ %s hdma%c, host#=%ld, fw=%s\n",
    >  ...
    >
    > message yet.
    >
    > Which means that the crash occurs between qla2x00_request_irqs()
    > and printing that message.

Close this window by enabling RISC interrupts after the host has
been registered with the SCSI midlayer.

Reported-by: Josip Rodin <joy@entuzijast.net>
Cc: Stable Tree <stable@kernel.org>
Signed-off-by: Andrew Vasquez <andrew.vasquez@qlogic.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

2 files changed, 2 insertions, 1 deletions

diff --git a/drivers/scsi/qla2xxx/qla_isr.c b/drivers/scsi/qla2xxx/qla_isr.c
index 45a3b93eed57..bf41887cdd65 100644
--- a/drivers/scsi/qla2xxx/qla_isr.c
+++ b/drivers/scsi/qla2xxx/qla_isr.c
@@ -1834,7 +1834,6 @@ clear_risc_ints:
                 WRT_REG_WORD(&reg->isp.hccr, HCCR_CLR_HOST_INT);
         }
         spin_unlock_irq(&ha->hardware_lock);
-        ha->isp_ops->enable_intrs(ha);
 
 fail:
         return ret;
diff --git a/drivers/scsi/qla2xxx/qla_os.c b/drivers/scsi/qla2xxx/qla_os.c
index 26afe44265c7..6d0f0e5f2827 100644
--- a/drivers/scsi/qla2xxx/qla_os.c
+++ b/drivers/scsi/qla2xxx/qla_os.c
@@ -1740,6 +1740,8 @@ qla2x00_probe_one(struct pci_dev *pdev, const struct pci_device_id *id)
         if (ret)
                 goto probe_failed;
 
+        ha->isp_ops->enable_intrs(ha);
+
         scsi_scan_host(host);
 
         qla2x00_alloc_sysfs_attr(ha);