scsi: zfcp: diagnostics buffer caching and use for exchange port data

The FCP channel exposes two central interfaces to receive information about
the local FCP-Adapter/-Port: Exchange Port and Exchange Config Data. Using
these commands can negatively impact the adapter if we allow them to be
sent at a very high rate.

The later parts of this patchset will introduce new user-interfaces to
receive more diagnostics from the adapter. To prevent any negative impact
from using those, this patch adds a simple caching-mechanism that will
prevent a malicious/faulty userspace-application from generating an
abnormal high amount of Exchange Port/Config Data traffic.

Relevant diagnostic data that is received via Exchange Config/Port Data is
cached in buffers associated with the corresponding adapter-struct.  Each
buffer is associated with a timestamp that signals how old the data is,
and, added via a following patch in this series, lets userspace-interfaces
determine when the data is too old and needs to be updated.

Buffer-updates are made during the normal response path of the
corresponding command. With this patch only the output of the Exchange Port
Data command is captured.

Link: https://lore.kernel.org/r/054ca020ce0a53dc0d9176428bea373898944e6a.1572018130.git.bblock@linux.ibm.com
Reviewed-by: Steffen Maier <maier@linux.ibm.com>
Signed-off-by: Benjamin Block <bblock@linux.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c
index e390f8c6d5f3..a19189d7b3f3 100644
--- a/drivers/s390/scsi/zfcp_aux.c
+++ b/drivers/s390/scsi/zfcp_aux.c
@@ -4,7 +4,7 @@
  *
  * Module interface and handling of zfcp data structures.
  *
- * Copyright IBM Corp. 2002, 2017
+ * Copyright IBM Corp. 2002, 2018
  */
 
 /*
@@ -25,6 +25,7 @@
  *            Martin Petermann
  *            Sven Schuetz
  *            Steffen Maier
+ *	      Benjamin Block
  */
 
 #define KMSG_COMPONENT "zfcp"
@@ -36,6 +37,7 @@
 #include "zfcp_ext.h"
 #include "zfcp_fc.h"
 #include "zfcp_reqlist.h"
+#include "zfcp_diag.h"
 
 #define ZFCP_BUS_ID_SIZE	20
 
@@ -356,6 +358,9 @@ struct zfcp_adapter *zfcp_adapter_enqueue(struct ccw_device *ccw_device)
 
 	adapter->erp_action.adapter = adapter;
 
+	if (zfcp_diag_adapter_setup(adapter))
+		goto failed;
+
 	if (zfcp_qdio_setup(adapter))
 		goto failed;
 
@@ -449,6 +454,7 @@ void zfcp_adapter_release(struct kref *ref)
 	dev_set_drvdata(&adapter->ccw_device->dev, NULL);
 	zfcp_fc_gs_destroy(adapter);
 	zfcp_free_low_mem_buffers(adapter);
+	zfcp_diag_adapter_free(adapter);
 	kfree(adapter->req_list);
 	kfree(adapter->fc_stats);
 	kfree(adapter->stats_reset_data);