On 04.10.2016 16:24, Bart Van Assche wrote:
On 10/04/16 07:00, Gioh Kim wrote:
Standard SCSI device has host_reset sysfs interface.
This patch exports the host_reset interface for upper layer.

Signed-off-by: Gioh Kim <gi-oh....@profitbricks.com>
---
 drivers/infiniband/ulp/srp/ib_srp.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/infiniband/ulp/srp/ib_srp.c b/drivers/infiniband/ulp/srp/ib_srp.c
index 3322ed7..92e6c3f 100644
--- a/drivers/infiniband/ulp/srp/ib_srp.c
+++ b/drivers/infiniband/ulp/srp/ib_srp.c
@@ -2628,6 +2628,15 @@ static int srp_reset_device(struct scsi_cmnd *scmnd)
     return SUCCESS;
 }

+static int srp_scsi_host_reset(struct Scsi_Host *shost, int reset_type)
+{
+    struct srp_target_port *target = host_to_target(shost);
+
+ shost_printk(KERN_EMERG, target->scsi_host, PFX "SRP reset_host called\n");
+
+    return srp_reconnect_rport(target->rport);
+}
+
 static int srp_reset_host(struct scsi_cmnd *scmnd)
 {
struct srp_target_port *target = host_to_target(scmnd->device->host);
@@ -2858,6 +2867,7 @@ static struct scsi_host_template srp_template = {
     .use_clustering            = ENABLE_CLUSTERING,
     .shost_attrs            = srp_host_attrs,
     .track_queue_depth        = 1,
+    .host_reset            = srp_scsi_host_reset,
 };

Hello Gioh,

A patch description should not only explain what is changed but also why a change is considered useful. Why do you think it would be useful to allow users to trigger a call of srp_reconnect_rport() through sysfs instead of using the functionality that is already available through sysfs, namely removing a SCSI host and reconnecting?
Hello Bart,

It's my mistake to miss 0000-cover-letter.patch file including description.

I'm testing SCSI devices which are exported by the remote servers via IB network. I know that SCSI error handling mechanism calls reset-host when something wrong happens. But the SCSI error handling tries sending ABORT commands and other actions before resetting host. I found that those ABORT commands could generate more stress on the remove server. So I need to reset SCSI host (which mean reconnecting) when the remote server starts to become slow or have some problem to handle IO.

And I think I can use some utilities for SCSI device, such like sg3 utils, to handle srp connection.

Thank you for your reply.

Best regards,
Gioh Kim


Bart.


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