[patch 12/71] SCSI: qla2xxx: Defer enablement of RISC interruptsuntil ISP initialization completes.

[Greg KH]

2.6.26-stable review patch.  If anyone has any objections, please let us
know.

------------------
From: Andrew Vasquez <andrew.vasquez@xxxxxxxxxx>

commit 048feec5548c0582ee96148c61b87cccbcb5f9be upstream

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@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Vasquez <andrew.vasquez@xxxxxxxxxx>
Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/scsi/qla2xxx/qla_isr.c |    1 -
 drivers/scsi/qla2xxx/qla_os.c  |    2 ++
 2 files changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/scsi/qla2xxx/qla_isr.c
+++ b/drivers/scsi/qla2xxx/qla_isr.c
@@ -1838,7 +1838,6 @@ 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;
--- 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, 
 	if (ret)
 		goto probe_failed;
 
+	ha->isp_ops->enable_intrs(ha);
+
 	scsi_scan_host(host);
 
 	qla2x00_alloc_sysfs_attr(ha);

-- 
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