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.
Reviewed-by: Steffen Maier <maier@xxxxxxxxxxxxx>
Signed-off-by: Benjamin Block <bblock@xxxxxxxxxxxxx>
---
drivers/s390/scsi/Makefile | 2 +-
drivers/s390/scsi/zfcp_aux.c | 8 +++-
drivers/s390/scsi/zfcp_def.h | 3 +-
drivers/s390/scsi/zfcp_diag.c | 93 +++++++++++++++++++++++++++++++++++++++++++
drivers/s390/scsi/zfcp_diag.h | 60 ++++++++++++++++++++++++++++
drivers/s390/scsi/zfcp_fsf.c | 12 ++++++
6 files changed, 175 insertions(+), 3 deletions(-)
create mode 100644 drivers/s390/scsi/zfcp_diag.c
create mode 100644 drivers/s390/scsi/zfcp_diag.h
diff --git a/drivers/s390/scsi/Makefile b/drivers/s390/scsi/Makefile
index 9dda431ec8f3..352056eb0dd1 100644
--- a/drivers/s390/scsi/Makefile
+++ b/drivers/s390/scsi/Makefile
@@ -5,6 +5,6 @@
zfcp-objs := zfcp_aux.o zfcp_ccw.o zfcp_dbf.o zfcp_erp.o \
zfcp_fc.o zfcp_fsf.o zfcp_qdio.o zfcp_scsi.o zfcp_sysfs.o \
- zfcp_unit.o
+ zfcp_unit.o zfcp_diag.o
obj-$(CONFIG_ZFCP) += zfcp.o
diff --git a/drivers/s390/scsi/zfcp_aux.c b/drivers/s390/scsi/zfcp_aux.c
index e390f8c6d5f3..3ddc7147ac4f 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);
diff --git a/drivers/s390/scsi/zfcp_def.h b/drivers/s390/scsi/zfcp_def.h
index f5acdb67442e..8cc0eefe4ccc 100644
--- a/drivers/s390/scsi/zfcp_def.h
+++ b/drivers/s390/scsi/zfcp_def.h
@@ -4,7 +4,7 @@
*
* Global definitions for the zfcp device driver.
*
- * Copyright IBM Corp. 2002, 2017
+ * Copyright IBM Corp. 2002, 2018
*/
#ifndef ZFCP_DEF_H
@@ -198,6 +198,7 @@ struct zfcp_adapter {
struct device_dma_parameters dma_parms;
struct zfcp_fc_events events;
unsigned long next_port_scan;
+ struct zfcp_diag_adapter *diagnostics;
};
struct zfcp_port {
diff --git a/drivers/s390/scsi/zfcp_diag.c b/drivers/s390/scsi/zfcp_diag.c
new file mode 100644
index 000000000000..ca56a8f136ca
--- /dev/null
+++ b/drivers/s390/scsi/zfcp_diag.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * zfcp device driver
+ *
+ * Functions to handle diagnostics.
+ *
+ * Copyright IBM Corp. 2018
+ */
+
+#include <linux/spinlock.h>
+#include <linux/jiffies.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+
+#include "zfcp_diag.h"
+#include "zfcp_ext.h"
+#include "zfcp_def.h"
+
+/* Max age of data in a diagnostics buffer before it needs a refresh (in ms). */
+#define ZFCP_DIAG_MAX_AGE (5 * 1000)
+
+/**
+ * zfcp_diag_adapter_setup() - Setup storage for adapter diagnostics.
+ * @adapter: the adapter to setup diagnostics for.
+ *
+ * Creates the data-structures to store the diagnostics for an adapter. This
+ * overwrites whatever was stored before at &zfcp_adapter->diagnostics!
+ *
+ * Return:
+ * * 0 - Everyting is OK
+ * * -ENOMEM - Could not allocate all/parts of the data-structures;
+ * &zfcp_adapter->diagnostics remains unchanged
+ */
+int zfcp_diag_adapter_setup(struct zfcp_adapter *const adapter)
+{
+ struct zfcp_diag_adapter *diag;
+ struct zfcp_diag_header *hdr;
+
+ diag = kzalloc(sizeof(*diag), GFP_KERNEL);
+ if (diag == NULL)
+ return -ENOMEM;
+
+ /* setup header for port_data */
+ hdr = &diag->port_data.header;
+
+ spin_lock_init(&hdr->access_lock);
+ hdr->buffer = &diag->port_data.data;
+ hdr->buffer_size = sizeof(diag->port_data.data);
+ /* set the timestamp so that the first test on age will always fail */
+ hdr->timestamp = jiffies - msecs_to_jiffies(ZFCP_DIAG_MAX_AGE);
+
+ adapter->diagnostics = diag;
+ return 0;
+}
+
+/**
+ * zfcp_diag_adapter_free() - Frees all adapter diagnostics allocations.
+ * @adapter: the adapter whose diagnostic structures should be freed.
+ *
+ * Frees all data-structures in the given adapter that store diagnostics
+ * information. Can savely be called with partially setup diagnostics.
+ */
+void zfcp_diag_adapter_free(struct zfcp_adapter *const adapter)
+{
+ kfree(adapter->diagnostics);
+ adapter->diagnostics = NULL;
+}
+
+/**
+ * zfcp_diag_update_xdata() - Update a diagnostics buffer.
+ * @hdr: the meta data to update.
+ * @data: data to use for the update.
+ * @incomplete: flag stating whether the data in @data is incomplete.
+ */
+void zfcp_diag_update_xdata(struct zfcp_diag_header *const hdr,
+ const void *const data, const bool incomplete)
+{
+ const unsigned long capture_timestamp = jiffies;
+ unsigned long flags;
+
+ spin_lock_irqsave(&hdr->access_lock, flags);
+
+ /* make sure we never go into the past with an update */
+ if (!time_after_eq(capture_timestamp, hdr->timestamp))
+ goto out;
+
+ hdr->timestamp = capture_timestamp;
+ hdr->incomplete = incomplete;
+ memcpy(hdr->buffer, data, hdr->buffer_size);
+out:
+ spin_unlock_irqrestore(&hdr->access_lock, flags);
+}
diff --git a/drivers/s390/scsi/zfcp_diag.h b/drivers/s390/scsi/zfcp_diag.h
new file mode 100644
index 000000000000..5c81e7a8b8d7
--- /dev/null
+++ b/drivers/s390/scsi/zfcp_diag.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * zfcp device driver
+ *
+ * Definitions for handling diagnostics in the the zfcp device driver.
+ *
+ * Copyright IBM Corp. 2018
+ */
+
+#ifndef ZFCP_DIAG_H
+#define ZFCP_DIAG_H
+
+#include <linux/spinlock.h>
+
+#include "zfcp_fsf.h"
+#include "zfcp_def.h"
+
+/**
+ * struct zfcp_diag_header - general part of a diagnostic buffer.
+ * @access_lock: lock protecting all the data in this buffer.
+ * @updating: flag showing that an update for this buffer is currently running.
+ * @incomplete: flag showing that the data in @buffer is incomplete.
+ * @timestamp: time in jiffies when the data of this buffer was last captured.
+ * @buffer: implementation-depending data of this buffer
+ * @buffer_size: size of @buffer
+ */
+struct zfcp_diag_header {
+ spinlock_t access_lock;
+
+ /* Flags */
+ u64 updating :1;
+ u64 incomplete :1;
+
+ unsigned long timestamp;
+
+ void *buffer;
+ size_t buffer_size;
+};
+
+/**
+ * struct zfcp_diag_adapter - central storage for all diagnostics concerning an
+ * adapter.
+ * @port_data: data retrieved using exchange port data.
+ * @port_data.header: header with metadata for the cache in @port_data.data.
+ * @port_data.data: cached QTCB Bottom of command exchange port data.
+ */
+struct zfcp_diag_adapter {
+ struct {
+ struct zfcp_diag_header header;
+ struct fsf_qtcb_bottom_port data;
+ } port_data;
+};
+
+int zfcp_diag_adapter_setup(struct zfcp_adapter *const adapter);
+void zfcp_diag_adapter_free(struct zfcp_adapter *const adapter);
+
+void zfcp_diag_update_xdata(struct zfcp_diag_header *const hdr,
+ const void *const data, const bool incomplete);
+
+#endif /* ZFCP_DIAG_H */
diff --git a/drivers/s390/scsi/zfcp_fsf.c b/drivers/s390/scsi/zfcp_fsf.c
index 808e3f6200ae..310cc937d1f1 100644
--- a/drivers/s390/scsi/zfcp_fsf.c
+++ b/drivers/s390/scsi/zfcp_fsf.c
@@ -11,6 +11,7 @@
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/blktrace_api.h>
+#include <linux/jiffies.h>
#include <linux/slab.h>
#include <scsi/fc/fc_els.h>
#include "zfcp_ext.h"
@@ -18,6 +19,7 @@
#include "zfcp_dbf.h"
#include "zfcp_qdio.h"
#include "zfcp_reqlist.h"
+#include "zfcp_diag.h"
/* timeout for FSF requests sent during scsi_eh: abort or FCP TMF */
#define ZFCP_FSF_SCSI_ER_TIMEOUT (10*HZ)
@@ -644,16 +646,26 @@ static void zfcp_fsf_exchange_port_evaluate(struct zfcp_fsf_req *req)
static void zfcp_fsf_exchange_port_data_handler(struct zfcp_fsf_req *req)
{
+ struct zfcp_diag_header *const diag_hdr =
+ &req->adapter->diagnostics->port_data.header;
struct fsf_qtcb *qtcb = req->qtcb;
+ struct fsf_qtcb_bottom_port *bottom = &qtcb->bottom.port;
if (req->status & ZFCP_STATUS_FSFREQ_ERROR)
return;
switch (qtcb->header.fsf_status) {
case FSF_GOOD:
+ /*
+ * usually we wait with an update till the cache is too old,
+ * but because we have the data available, update it anyway
+ */
+ zfcp_diag_update_xdata(diag_hdr, bottom, false);
+
zfcp_fsf_exchange_port_evaluate(req);
break;
case FSF_EXCHANGE_CONFIG_DATA_INCOMPLETE:
+ zfcp_diag_update_xdata(diag_hdr, bottom, true);
req->status |= ZFCP_STATUS_FSFREQ_XDATAINCOMPLETE;
zfcp_fsf_exchange_port_evaluate(req);
--
2.16.4
