Re: [PATCH 09/15] qedf: Add bus_reset No-op.

[Bart Van Assche]

On Tue, 2017-05-23 at 06:19 -0700, Dupuis, Chad wrote:
> We need to add a bus reset no-op as without it some of the LUNs attached to a
> vport may go offline when the error handler escalates to host reset due to not
> having a bus reset handler in the driver. What happens is we escalate to host
> reset which does a soft link down/link up to reset the adapter. However with
> multiple vports attached it's been observed that if the vports do log back 
> into
> the target within 5 seconds, the SCSI layer offlines the devices most likely
> due to a TUR timing out to verify that the device is online. Adding a bus
> reset handler will cause the TUR to be sent after the bus reset handler where
> the devices will still be online if the bus reset is initiated by sg_reset
> (which is the case in the test that was failing). The bus reset will succeed
> and not needlessly bring the device offline/online.

Reviewed-by: Bart Van Assche 

[PATCH 09/15] qedf: Add bus_reset No-op.

[Dupuis, Chad]

We need to add a bus reset no-op as without it some of the LUNs attached to a
vport may go offline when the error handler escalates to host reset due to not
having a bus reset handler in the driver. What happens is we escalate to host
reset which does a soft link down/link up to reset the adapter. However with
multiple vports attached it's been observed that if the vports do log back into
the target within 5 seconds, the SCSI layer offlines the devices most likely
due to a TUR timing out to verify that the device is online. Adding a bus
reset handler will cause the TUR to be sent after the bus reset handler where
the devices will still be online if the bus reset is initiated by sg_reset
(which is the case in the test that was failing). The bus reset will succeed
and not needlessly bring the device offline/online.

Signed-off-by: Chad Dupuis 
---
 drivers/scsi/qedf/qedf_main.c | 11 +++
 1 file changed, 11 insertions(+)

diff --git a/drivers/scsi/qedf/qedf_main.c b/drivers/scsi/qedf/qedf_main.c
index fa5a2f8..7dae915 100644
--- a/drivers/scsi/qedf/qedf_main.c
+++ b/drivers/scsi/qedf/qedf_main.c
@@ -628,6 +628,16 @@ static int qedf_eh_device_reset(struct scsi_cmnd *sc_cmd)
return qedf_initiate_tmf(sc_cmd, FCP_TMF_LUN_RESET);
 }
 
+static int qedf_eh_bus_reset(struct scsi_cmnd *sc_cmd)
+{
+   QEDF_ERR(NULL, "BUS RESET Issued...\n");
+   /*
+* Essentially a no-op but return SUCCESS to prevent
+* unnecessary escalation to the host reset handler.
+*/
+   return SUCCESS;
+}
+
 void qedf_wait_for_upload(struct qedf_ctx *qedf)
 {
while (1) {
@@ -705,6 +715,7 @@ static int qedf_slave_configure(struct scsi_device *sdev)
.eh_abort_handler   = qedf_eh_abort,
.eh_device_reset_handler = qedf_eh_device_reset, /* lun reset */
.eh_target_reset_handler = qedf_eh_target_reset, /* target reset */
+   .eh_bus_reset_handler = qedf_eh_bus_reset,
.eh_host_reset_handler  = qedf_eh_host_reset,
.slave_configure= qedf_slave_configure,
.dma_boundary = QED_HW_DMA_BOUNDARY,
-- 
1.8.5.6