[PATCH scsi-rc-fixes] qla2xxx: Defer enablement of RISC interrupts until ISP initialization completes.

Andrew Vasquez
2008-09-12T05:19:45Z

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

diff --git a/drivers/scsi/qla2xxx/qla_isr.c b/drivers/scsi/qla2xxx/qla_isr.c
index e50752e..fc4bfa7 100644
--- a/drivers/scsi/qla2xxx/qla_isr.c
+++ b/drivers/scsi/qla2xxx/qla_isr.c
@@ -1837,7 +1837,6 @@ 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 fcbcd44..3433441 100644
--- a/drivers/scsi/qla2xxx/qla_os.c
+++ b/drivers/scsi/qla2xxx/qla_os.c
@@ -1739,6 +1739,8 @@ 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);
--
1.6.0.1.267.gec3a