[RFC PATCH] scsi: scsi_transport_fc: Create a lightweight option for Virtual FC Hosts.

From: Cathy Avery
Date: Wed Jan 04 2017 - 10:39:56 EST

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This patch represents an attempt to resurrect the conversation
based on the submission of patch:

[PATCH 1/1] scsi: storvsc: Support manual scan of FC hosts on Hyper-V
K. Y. Srinivasan kys at microsoft.com
Sat Mar 12 21:52:48 UTC 2016

http://driverdev.linuxdriverproject.org/pipermail/driverdev-devel/2016-March/087116.html

That patch attempted to address the problem of not being able to scan FC
hosts on a Hyper-V guest via sysfs due to the fact that they did not
contain the complete characteristic set associated with a normal FC host
( missing rports, vports, etc ). These new lightweight hosts as they
were subsequently referred to are not consistent with the current FC
transport model.

The patch below provides a method to reconcile the issue by offering
a lightweight option to the current FC transport class. The new option
is selected by a driver when it indicates it wants the lightweight
transport in fc_function_template. I have included the changes for
storvsc_drv.c in this patch as an example of a driver making use of the
lightweight transport option.

Signed-off-by: Cathy Avery <cavery@xxxxxxxxxx>
---
drivers/scsi/scsi_transport_fc.c | 125 +++++++++++++++++++++++++++++++++++++--
drivers/scsi/storvsc_drv.c | 6 +-
include/scsi/scsi_transport_fc.h | 1 +
3 files changed, 123 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
index 03577bd..4adc669 100644
--- a/drivers/scsi/scsi_transport_fc.c
+++ b/drivers/scsi/scsi_transport_fc.c
@@ -50,6 +50,15 @@ static int fc_bsg_hostadd(struct Scsi_Host *, struct fc_host_attrs *);
static int fc_bsg_rportadd(struct Scsi_Host *, struct fc_rport *);
static void fc_bsg_remove(struct request_queue *);
static void fc_bsg_goose_queue(struct fc_rport *);
+static int fc_host_lw_setup(struct Scsi_Host *, struct fc_host_attrs *);
+static int fc_host_hw_setup(struct Scsi_Host *, struct fc_host_attrs *);
+static int fc_host_hw_remove(struct fc_host_attrs *);
+static struct scsi_transport_template *
+ fc_attach_lw_transport(struct fc_function_template *);
+static struct scsi_transport_template *
+ fc_attach_hw_transport(struct fc_function_template *);
+static void fc_remove_lw_host(struct Scsi_Host *);
+static void fc_remove_hw_host(struct Scsi_Host *, struct fc_host_attrs *);

/*
* Module Parameters
@@ -352,6 +361,10 @@ struct fc_internal {

#define to_fc_internal(tmpl) container_of(tmpl, struct fc_internal, t)

+
+static void fc_release_lw_transport(struct fc_internal *);
+static void fc_release_hw_transport(struct fc_internal *);
+
static int fc_target_setup(struct transport_container *tc, struct device *dev,
struct device *cdev)
{
@@ -387,7 +400,26 @@ static int fc_host_setup(struct transport_container *tc, struct device *dev,
{
struct Scsi_Host *shost = dev_to_shost(dev);
struct fc_host_attrs *fc_host = shost_to_fc_host(shost);
+ struct fc_internal *i = to_fc_internal(shost->transportt);
+
+ if (i->f->lightweight_transport)
+ return fc_host_lw_setup(shost, fc_host);
+
+ return fc_host_hw_setup(shost, fc_host);
+}
+
+static int fc_host_lw_setup(struct Scsi_Host *shost,
+ struct fc_host_attrs *fc_host)
+{
+ fc_host->node_name = -1;
+ fc_host->port_name = -1;
+
+ return 0;
+}

+static int fc_host_hw_setup(struct Scsi_Host *shost,
+ struct fc_host_attrs *fc_host)
+{
/*
* Set default values easily detected by the midlayer as
* failure cases. The scsi lldd is responsible for initializing
@@ -468,7 +500,16 @@ static int fc_host_remove(struct transport_container *tc, struct device *dev,
{
struct Scsi_Host *shost = dev_to_shost(dev);
struct fc_host_attrs *fc_host = shost_to_fc_host(shost);
+ struct fc_internal *i = to_fc_internal(shost->transportt);
+
+ if (i->f->lightweight_transport)
+ return 0;

+ return fc_host_hw_remove(fc_host);
+}
+
+static int fc_host_hw_remove(struct fc_host_attrs *fc_host)
+{
fc_bsg_remove(fc_host->rqst_q);
return 0;
}
@@ -2175,6 +2216,49 @@ static int fc_it_nexus_response(struct Scsi_Host *shost, u64 nexus, int result)
struct scsi_transport_template *
fc_attach_transport(struct fc_function_template *ft)
{
+ if (ft->lightweight_transport)
+ return fc_attach_lw_transport(ft);
+
+ return fc_attach_hw_transport(ft);
+}
+EXPORT_SYMBOL(fc_attach_transport);
+
+
+struct scsi_transport_template *
+fc_attach_lw_transport(struct fc_function_template *ft)
+{
+ int count;
+ struct fc_internal *i;
+
+ i = kzalloc(sizeof(struct fc_internal),
+ GFP_KERNEL);
+
+ if (unlikely(!i))
+ return NULL;
+
+ i->t.host_attrs.ac.attrs = &i->host_attrs[0];
+ i->t.host_attrs.ac.class = &fc_host_class.class;
+ i->t.host_attrs.ac.match = fc_host_match;
+ i->t.host_size = sizeof(struct fc_host_attrs);
+ transport_container_register(&i->t.host_attrs);
+
+ i->f = ft;
+
+ count = 0;
+ SETUP_HOST_ATTRIBUTE_RD(node_name);
+ SETUP_HOST_ATTRIBUTE_RD(port_name);
+
+ BUG_ON(count > FC_HOST_NUM_ATTRS);
+
+ i->host_attrs[count] = NULL;
+
+ return &i->t;
+}
+
+
+struct scsi_transport_template *
+fc_attach_hw_transport(struct fc_function_template *ft)
+{
int count;
struct fc_internal *i = kzalloc(sizeof(struct fc_internal),
GFP_KERNEL);
@@ -2318,12 +2402,27 @@ fc_attach_transport(struct fc_function_template *ft)

return &i->t;
}
-EXPORT_SYMBOL(fc_attach_transport);

void fc_release_transport(struct scsi_transport_template *t)
{
struct fc_internal *i = to_fc_internal(t);

+ if (i->f->lightweight_transport)
+ fc_release_lw_transport(i);
+ else
+ fc_release_hw_transport(i);
+}
+EXPORT_SYMBOL(fc_release_transport);
+
+void fc_release_lw_transport(struct fc_internal *i)
+{
+ transport_container_unregister(&i->t.host_attrs);
+
+ kfree(i);
+}
+
+void fc_release_hw_transport(struct fc_internal *i)
+{
transport_container_unregister(&i->t.target_attrs);
transport_container_unregister(&i->t.host_attrs);
transport_container_unregister(&i->rport_attr_cont);
@@ -2331,7 +2430,6 @@ void fc_release_transport(struct scsi_transport_template *t)

kfree(i);
}
-EXPORT_SYMBOL(fc_release_transport);

/**
* fc_queue_work - Queue work to the fc_host workqueue.
@@ -2438,10 +2536,30 @@ fc_flush_devloss(struct Scsi_Host *shost)
void
fc_remove_host(struct Scsi_Host *shost)
{
+ struct fc_host_attrs *fc_host = shost_to_fc_host(shost);
+ struct fc_internal *i = to_fc_internal(shost->transportt);
+
+ if (i->f->lightweight_transport)
+ fc_remove_lw_host(shost);
+
+ else
+ fc_remove_hw_host(shost, fc_host);
+}
+EXPORT_SYMBOL(fc_remove_host);
+
+void
+fc_remove_lw_host(struct Scsi_Host *shost)
+{
+ /* flush all scan work items */
+ scsi_flush_work(shost);
+}
+
+void
+fc_remove_hw_host(struct Scsi_Host *shost, struct fc_host_attrs *fc_host)
+{
struct fc_vport *vport = NULL, *next_vport = NULL;
struct fc_rport *rport = NULL, *next_rport = NULL;
struct workqueue_struct *work_q;
- struct fc_host_attrs *fc_host = shost_to_fc_host(shost);
unsigned long flags;

spin_lock_irqsave(shost->host_lock, flags);
@@ -2484,7 +2602,6 @@ fc_remove_host(struct Scsi_Host *shost)
destroy_workqueue(work_q);
}
}
-EXPORT_SYMBOL(fc_remove_host);

static void fc_terminate_rport_io(struct fc_rport *rport)
{
diff --git a/drivers/scsi/storvsc_drv.c b/drivers/scsi/storvsc_drv.c
index 888e16e..fc1d6ba 100644
--- a/drivers/scsi/storvsc_drv.c
+++ b/drivers/scsi/storvsc_drv.c
@@ -1882,6 +1882,7 @@ static struct hv_driver storvsc_drv = {
static struct fc_function_template fc_transport_functions = {
.show_host_node_name = 1,
.show_host_port_name = 1,
+ .lightweight_transport = 1,
};
#endif

@@ -1906,11 +1907,6 @@ static int __init storvsc_drv_init(void)
fc_transport_template = fc_attach_transport(&fc_transport_functions);
if (!fc_transport_template)
return -ENODEV;
-
- /*
- * Install Hyper-V specific timeout handler.
- */
- fc_transport_template->eh_timed_out = storvsc_eh_timed_out;
#endif

ret = vmbus_driver_register(&storvsc_drv);
diff --git a/include/scsi/scsi_transport_fc.h b/include/scsi/scsi_transport_fc.h
index 924c8e6..b1c03cc 100644
--- a/include/scsi/scsi_transport_fc.h
+++ b/include/scsi/scsi_transport_fc.h
@@ -718,6 +718,7 @@ struct fc_function_template {
unsigned long show_host_system_hostname:1;

unsigned long disable_target_scan:1;
+ unsigned long lightweight_transport:1;
};

--
2.5.0

Next message: Luis R. Rodriguez: "Re: [PATCH] firmware: Prevent oops on delayed abort"
Previous message: Mika Westerberg: "[PATCH 4/6] pinctrl: intel: Add support for hardware debouncer"
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