[patch 0/3] zfcp FC BSG timeout fixes for 2.6.33-rc4

[patch 0/3] zfcp FC BSG timeout fixes for 2.6.33-rc4

[Christof Schmitt]

Here is the patch series for the FC BSG timeout problem. It is based
on the initial proposal here:
http://marc.info/?l=linux-scsi&m=126043474110957&w=2

To summarize the problem and the approach taken: The block layer runs
a timer for each FC BSG request. When the timer expires, the LLD's
bsg_timeout function is called to abort the request.  With zfcp, the
hardware does not support aborting the CT or ELS request. Instead the
hardware runs an internal timer that is setup from Linux for each CT
and BSG request. When the request times out in the block layer, the
request data structures are destroyed. When the still pending hardware
request returns, it will access already freed memory.

The solution taken here is to add a special return code to the
bsg_timeout callback to indicate that the block layer timer should be
reset. zfcp uses this to prevent the block layer timeout. To return
the FC BSG request in the time requested by the user, the hardware
timer is setup with the timeout value from the FC BSG request.

The patches apply cleanly on top of 2.6.33-rc4 and the zfcp fixes
posted yesterday.

--
Christof Schmitt

[patch 1/3] scsi_transport_fc: Allow LLD to reset FC BSG timeout

[Christof Schmitt]

[-- Attachment #1: bsg_job_timeout.patch --]
[-- Type: text/plain, Size: 1095 bytes --]

From: Swen Schillig <swen@vnet.ibm.com>

The hardware used with zfcp cannot abort a currently pending CT or ELS
request. Therefore we need the option to postpone the timeout
triggered request abort within the fc layer, since there is nothing
zfcp can do to stop the request at this point.

Cc: James Smart <James.Smart@emulex.com>
Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
---
 drivers/scsi/scsi_transport_fc.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/scsi/scsi_transport_fc.c	2010-01-14 16:44:42.000000000 +0100
+++ b/drivers/scsi/scsi_transport_fc.c	2010-01-14 16:44:43.000000000 +0100
@@ -3527,7 +3527,10 @@ fc_bsg_job_timeout(struct request *req)
 	if (!done && i->f->bsg_timeout) {
 		/* call LLDD to abort the i/o as it has timed out */
 		err = i->f->bsg_timeout(job);
-		if (err)
+		if (err == -EAGAIN) {
+			job->ref_cnt--;
+			return BLK_EH_RESET_TIMER;
+		} else if (err)
 			printk(KERN_ERR "ERROR: FC BSG request timeout - LLD "
 				"abort failed with status %d\n", err);
 	}

[patch 2/3] zfcp: Introduce bsg_timeout callback.

[Christof Schmitt]

[-- Attachment #1: zfcp_bsg_timeout.patch --]
[-- Type: text/plain, Size: 2158 bytes --]

From: Swen Schillig <swen@vnet.ibm.com>

Introduce a zfcp callback for timeouts triggered from FC BSG.  With
zfcp, the underlying hardware cannot abort CT or ELS requests, so
there is nothing to do when the block layer timeout expires.  To avoid
interference with the block layer timeout, simply indicate that the
block layer timer should be reset. The timer running in the hardware
for the pending CT or ELS request will return the request when it
expires.

Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
---
 drivers/s390/scsi/zfcp_ext.h  |    1 +
 drivers/s390/scsi/zfcp_fc.c   |    6 ++++++
 drivers/s390/scsi/zfcp_scsi.c |    1 +
 3 files changed, 8 insertions(+)

--- a/drivers/s390/scsi/zfcp_ext.h	2010-01-14 17:00:09.000000000 +0100
+++ b/drivers/s390/scsi/zfcp_ext.h	2010-01-14 17:00:21.000000000 +0100
@@ -108,6 +108,7 @@ extern void zfcp_fc_wka_ports_force_offl
 extern int zfcp_fc_gs_setup(struct zfcp_adapter *);
 extern void zfcp_fc_gs_destroy(struct zfcp_adapter *);
 extern int zfcp_fc_exec_bsg_job(struct fc_bsg_job *);
+extern int zfcp_fc_timeout_bsg_job(struct fc_bsg_job *);
 
 /* zfcp_fsf.c */
 extern int zfcp_fsf_open_port(struct zfcp_erp_action *);
--- a/drivers/s390/scsi/zfcp_fc.c	2010-01-14 17:00:09.000000000 +0100
+++ b/drivers/s390/scsi/zfcp_fc.c	2010-01-14 17:00:43.000000000 +0100
@@ -788,6 +788,12 @@ int zfcp_fc_exec_bsg_job(struct fc_bsg_j
 	}
 }
 
+int zfcp_fc_timeout_bsg_job(struct fc_bsg_job *job)
+{
+	/* hardware tracks timeout, reset bsg timeout to not interfere */
+	return -EAGAIN;
+}
+
 int zfcp_fc_gs_setup(struct zfcp_adapter *adapter)
 {
 	struct zfcp_fc_wka_ports *wka_ports;
--- a/drivers/s390/scsi/zfcp_scsi.c	2010-01-14 17:00:09.000000000 +0100
+++ b/drivers/s390/scsi/zfcp_scsi.c	2010-01-14 17:00:21.000000000 +0100
@@ -652,6 +652,7 @@ struct fc_function_template zfcp_transpo
 	.show_host_port_state = 1,
 	.show_host_active_fc4s = 1,
 	.bsg_request = zfcp_fc_exec_bsg_job,
+	.bsg_timeout = zfcp_fc_timeout_bsg_job,
 	/* no functions registered for following dynamic attributes but
 	   directly set by LLDD */
 	.show_host_port_type = 1,

[patch 3/3] zfcp: Set hardware timeout as requested by BSG request.

[Christof Schmitt]

[-- Attachment #1: zfcp_set_timeout.patch --]
[-- Type: text/plain, Size: 5887 bytes --]

From: Swen Schillig <swen@vnet.ibm.com>

The hardware used with zfcp provides a timer for CT and ELS requests
instead of an abort capability for these commands. To correctly handle
the FC BSG timeouts, pass the timeout from the BSG requests to the
hardware.

Signed-off-by: Swen Schillig <swen@vnet.ibm.com>
---
 drivers/s390/scsi/zfcp_ext.h |    4 ++--
 drivers/s390/scsi/zfcp_fc.c  |   13 ++++++++-----
 drivers/s390/scsi/zfcp_fc.h  |    2 ++
 drivers/s390/scsi/zfcp_fsf.c |   19 ++++++++++---------
 4 files changed, 22 insertions(+), 16 deletions(-)

--- a/drivers/s390/scsi/zfcp_ext.h	2010-01-14 16:44:46.000000000 +0100
+++ b/drivers/s390/scsi/zfcp_ext.h	2010-01-14 16:44:49.000000000 +0100
@@ -130,9 +130,9 @@ extern void zfcp_fsf_req_dismiss_all(str
 extern int zfcp_fsf_status_read(struct zfcp_qdio *);
 extern int zfcp_status_read_refill(struct zfcp_adapter *adapter);
 extern int zfcp_fsf_send_ct(struct zfcp_fc_wka_port *, struct zfcp_fsf_ct_els *,
-			    mempool_t *);
+			    mempool_t *, unsigned int);
 extern int zfcp_fsf_send_els(struct zfcp_adapter *, u32,
-			     struct zfcp_fsf_ct_els *);
+			     struct zfcp_fsf_ct_els *, unsigned int);
 extern int zfcp_fsf_send_fcp_command_task(struct zfcp_unit *,
 					  struct scsi_cmnd *);
 extern void zfcp_fsf_req_free(struct zfcp_fsf_req *);
--- a/drivers/s390/scsi/zfcp_fc.c	2010-01-14 16:44:46.000000000 +0100
+++ b/drivers/s390/scsi/zfcp_fc.c	2010-01-14 16:44:49.000000000 +0100
@@ -258,7 +258,8 @@ static int zfcp_fc_ns_gid_pn_request(str
 	gid_pn->gid_pn_req.gid_pn.fn_wwpn = port->wwpn;
 
 	ret = zfcp_fsf_send_ct(&adapter->gs->ds, &gid_pn->ct,
-			       adapter->pool.gid_pn_req);
+			       adapter->pool.gid_pn_req,
+			       ZFCP_FC_CTELS_TMO);
 	if (!ret) {
 		wait_for_completion(&completion);
 		zfcp_fc_ns_gid_pn_eval(gid_pn);
@@ -421,7 +422,8 @@ static int zfcp_fc_adisc(struct zfcp_por
 	hton24(adisc->adisc_req.adisc_port_id,
 	       fc_host_port_id(adapter->scsi_host));
 
-	ret = zfcp_fsf_send_els(adapter, port->d_id, &adisc->els);
+	ret = zfcp_fsf_send_els(adapter, port->d_id, &adisc->els,
+				ZFCP_FC_CTELS_TMO);
 	if (ret)
 		kmem_cache_free(zfcp_data.adisc_cache, adisc);
 
@@ -532,7 +534,8 @@ static int zfcp_fc_send_gpn_ft(struct zf
 	ct->req = &gpn_ft->sg_req;
 	ct->resp = gpn_ft->sg_resp;
 
-	ret = zfcp_fsf_send_ct(&adapter->gs->ds, ct, NULL);
+	ret = zfcp_fsf_send_ct(&adapter->gs->ds, ct, NULL,
+			       ZFCP_FC_CTELS_TMO);
 	if (!ret)
 		wait_for_completion(&completion);
 	return ret;
@@ -734,7 +737,7 @@ static int zfcp_fc_exec_els_job(struct f
 		d_id = ntoh24(job->request->rqst_data.h_els.port_id);
 
 	els->handler = zfcp_fc_ct_els_job_handler;
-	return zfcp_fsf_send_els(adapter, d_id, els);
+	return zfcp_fsf_send_els(adapter, d_id, els, job->req->timeout / HZ);
 }
 
 static int zfcp_fc_exec_ct_job(struct fc_bsg_job *job,
@@ -753,7 +756,7 @@ static int zfcp_fc_exec_ct_job(struct fc
 		return ret;
 
 	ct->handler = zfcp_fc_ct_job_handler;
-	ret = zfcp_fsf_send_ct(wka_port, ct, NULL);
+	ret = zfcp_fsf_send_ct(wka_port, ct, NULL, job->req->timeout / HZ);
 	if (ret)
 		zfcp_fc_wka_port_put(wka_port);
 
--- a/drivers/s390/scsi/zfcp_fc.h	2010-01-14 16:44:41.000000000 +0100
+++ b/drivers/s390/scsi/zfcp_fc.h	2010-01-14 16:44:49.000000000 +0100
@@ -27,6 +27,8 @@
 #define ZFCP_FC_GPN_FT_MAX_ENT	  (ZFCP_FC_GPN_FT_NUM_BUFS * \
 					(ZFCP_FC_GPN_FT_ENT_PAGE + 1))
 
+#define ZFCP_FC_CTELS_TMO	(2 * FC_DEF_R_A_TOV / 1000)
+
 /**
  * struct zfcp_fc_gid_pn_req - container for ct header plus gid_pn request
  * @ct_hdr: FC GS common transport header
--- a/drivers/s390/scsi/zfcp_fsf.c	2010-01-14 16:44:41.000000000 +0100
+++ b/drivers/s390/scsi/zfcp_fsf.c	2010-01-14 16:44:49.000000000 +0100
@@ -1068,20 +1068,20 @@ static int zfcp_fsf_setup_ct_els_sbals(s
 static int zfcp_fsf_setup_ct_els(struct zfcp_fsf_req *req,
 				 struct scatterlist *sg_req,
 				 struct scatterlist *sg_resp,
-				 int max_sbals)
+				 int max_sbals, unsigned int timeout)
 {
 	int ret;
-	unsigned int fcp_chan_timeout;
 
 	ret = zfcp_fsf_setup_ct_els_sbals(req, sg_req, sg_resp, max_sbals);
 	if (ret)
 		return ret;
 
 	/* common settings for ct/gs and els requests */
-	fcp_chan_timeout = 2 * FC_DEF_R_A_TOV / 1000;
+	if (timeout > 255)
+		timeout = 255; /* max value accepted by hardware */
 	req->qtcb->bottom.support.service_class = FSF_CLASS_3;
-	req->qtcb->bottom.support.timeout = fcp_chan_timeout;
-	zfcp_fsf_start_timer(req, (fcp_chan_timeout + 10) * HZ);
+	req->qtcb->bottom.support.timeout = timeout;
+	zfcp_fsf_start_timer(req, (timeout + 10) * HZ);
 
 	return 0;
 }
@@ -1092,7 +1092,8 @@ static int zfcp_fsf_setup_ct_els(struct 
  * @pool: if non-null this mempool is used to allocate struct zfcp_fsf_req
  */
 int zfcp_fsf_send_ct(struct zfcp_fc_wka_port *wka_port,
-		     struct zfcp_fsf_ct_els *ct, mempool_t *pool)
+		     struct zfcp_fsf_ct_els *ct, mempool_t *pool,
+		     unsigned int timeout)
 {
 	struct zfcp_qdio *qdio = wka_port->adapter->qdio;
 	struct zfcp_fsf_req *req;
@@ -1111,7 +1112,7 @@ int zfcp_fsf_send_ct(struct zfcp_fc_wka_
 
 	req->status |= ZFCP_STATUS_FSFREQ_CLEANUP;
 	ret = zfcp_fsf_setup_ct_els(req, ct->req, ct->resp,
-				    FSF_MAX_SBALS_PER_REQ);
+				    FSF_MAX_SBALS_PER_REQ, timeout);
 	if (ret)
 		goto failed_send;
 
@@ -1188,7 +1189,7 @@ skip_fsfstatus:
  * @els: pointer to struct zfcp_send_els with data for the command
  */
 int zfcp_fsf_send_els(struct zfcp_adapter *adapter, u32 d_id,
-		      struct zfcp_fsf_ct_els *els)
+		      struct zfcp_fsf_ct_els *els, unsigned int timeout)
 {
 	struct zfcp_fsf_req *req;
 	struct zfcp_qdio *qdio = adapter->qdio;
@@ -1206,7 +1207,7 @@ int zfcp_fsf_send_els(struct zfcp_adapte
 	}
 
 	req->status |= ZFCP_STATUS_FSFREQ_CLEANUP;
-	ret = zfcp_fsf_setup_ct_els(req, els->req, els->resp, 2);
+	ret = zfcp_fsf_setup_ct_els(req, els->req, els->resp, 2, timeout);
 
 	if (ret)
 		goto failed_send;