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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>
This commit is contained in:
parent
92953c6e0a
commit
7e418833e6
6 changed files with 175 additions and 3 deletions
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@ -5,6 +5,6 @@
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zfcp-objs := zfcp_aux.o zfcp_ccw.o zfcp_dbf.o zfcp_erp.o \
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zfcp_fc.o zfcp_fsf.o zfcp_qdio.o zfcp_scsi.o zfcp_sysfs.o \
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zfcp_unit.o
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zfcp_unit.o zfcp_diag.o
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obj-$(CONFIG_ZFCP) += zfcp.o
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@ -4,7 +4,7 @@
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*
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* Module interface and handling of zfcp data structures.
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*
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* Copyright IBM Corp. 2002, 2017
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* Copyright IBM Corp. 2002, 2018
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*/
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/*
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@ -25,6 +25,7 @@
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* Martin Petermann
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* Sven Schuetz
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* Steffen Maier
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* Benjamin Block
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*/
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#define KMSG_COMPONENT "zfcp"
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@ -36,6 +37,7 @@
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#include "zfcp_ext.h"
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#include "zfcp_fc.h"
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#include "zfcp_reqlist.h"
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#include "zfcp_diag.h"
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#define ZFCP_BUS_ID_SIZE 20
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@ -356,6 +358,9 @@ struct zfcp_adapter *zfcp_adapter_enqueue(struct ccw_device *ccw_device)
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adapter->erp_action.adapter = adapter;
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if (zfcp_diag_adapter_setup(adapter))
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goto failed;
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if (zfcp_qdio_setup(adapter))
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goto failed;
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@ -449,6 +454,7 @@ void zfcp_adapter_release(struct kref *ref)
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dev_set_drvdata(&adapter->ccw_device->dev, NULL);
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zfcp_fc_gs_destroy(adapter);
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zfcp_free_low_mem_buffers(adapter);
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zfcp_diag_adapter_free(adapter);
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kfree(adapter->req_list);
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kfree(adapter->fc_stats);
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kfree(adapter->stats_reset_data);
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@ -4,7 +4,7 @@
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*
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* Global definitions for the zfcp device driver.
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*
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* Copyright IBM Corp. 2002, 2017
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* Copyright IBM Corp. 2002, 2018
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*/
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#ifndef ZFCP_DEF_H
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@ -198,6 +198,7 @@ struct zfcp_adapter {
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struct device_dma_parameters dma_parms;
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struct zfcp_fc_events events;
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unsigned long next_port_scan;
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struct zfcp_diag_adapter *diagnostics;
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};
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struct zfcp_port {
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93
drivers/s390/scsi/zfcp_diag.c
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93
drivers/s390/scsi/zfcp_diag.c
Normal file
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@ -0,0 +1,93 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* zfcp device driver
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*
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* Functions to handle diagnostics.
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*
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* Copyright IBM Corp. 2018
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*/
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#include <linux/spinlock.h>
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#include <linux/jiffies.h>
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#include <linux/string.h>
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#include <linux/errno.h>
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#include <linux/slab.h>
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#include "zfcp_diag.h"
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#include "zfcp_ext.h"
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#include "zfcp_def.h"
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/* Max age of data in a diagnostics buffer before it needs a refresh (in ms). */
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#define ZFCP_DIAG_MAX_AGE (5 * 1000)
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/**
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* zfcp_diag_adapter_setup() - Setup storage for adapter diagnostics.
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* @adapter: the adapter to setup diagnostics for.
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*
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* Creates the data-structures to store the diagnostics for an adapter. This
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* overwrites whatever was stored before at &zfcp_adapter->diagnostics!
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*
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* Return:
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* * 0 - Everyting is OK
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* * -ENOMEM - Could not allocate all/parts of the data-structures;
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* &zfcp_adapter->diagnostics remains unchanged
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*/
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int zfcp_diag_adapter_setup(struct zfcp_adapter *const adapter)
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{
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struct zfcp_diag_adapter *diag;
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struct zfcp_diag_header *hdr;
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diag = kzalloc(sizeof(*diag), GFP_KERNEL);
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if (diag == NULL)
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return -ENOMEM;
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/* setup header for port_data */
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hdr = &diag->port_data.header;
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spin_lock_init(&hdr->access_lock);
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hdr->buffer = &diag->port_data.data;
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hdr->buffer_size = sizeof(diag->port_data.data);
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/* set the timestamp so that the first test on age will always fail */
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hdr->timestamp = jiffies - msecs_to_jiffies(ZFCP_DIAG_MAX_AGE);
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adapter->diagnostics = diag;
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return 0;
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}
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/**
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* zfcp_diag_adapter_free() - Frees all adapter diagnostics allocations.
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* @adapter: the adapter whose diagnostic structures should be freed.
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*
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* Frees all data-structures in the given adapter that store diagnostics
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* information. Can savely be called with partially setup diagnostics.
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*/
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void zfcp_diag_adapter_free(struct zfcp_adapter *const adapter)
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{
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kfree(adapter->diagnostics);
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adapter->diagnostics = NULL;
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}
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/**
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* zfcp_diag_update_xdata() - Update a diagnostics buffer.
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* @hdr: the meta data to update.
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* @data: data to use for the update.
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* @incomplete: flag stating whether the data in @data is incomplete.
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*/
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void zfcp_diag_update_xdata(struct zfcp_diag_header *const hdr,
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const void *const data, const bool incomplete)
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{
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const unsigned long capture_timestamp = jiffies;
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unsigned long flags;
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spin_lock_irqsave(&hdr->access_lock, flags);
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/* make sure we never go into the past with an update */
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if (!time_after_eq(capture_timestamp, hdr->timestamp))
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goto out;
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hdr->timestamp = capture_timestamp;
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hdr->incomplete = incomplete;
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memcpy(hdr->buffer, data, hdr->buffer_size);
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out:
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spin_unlock_irqrestore(&hdr->access_lock, flags);
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}
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60
drivers/s390/scsi/zfcp_diag.h
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60
drivers/s390/scsi/zfcp_diag.h
Normal file
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* zfcp device driver
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*
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* Definitions for handling diagnostics in the the zfcp device driver.
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*
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* Copyright IBM Corp. 2018
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*/
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#ifndef ZFCP_DIAG_H
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#define ZFCP_DIAG_H
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#include <linux/spinlock.h>
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#include "zfcp_fsf.h"
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#include "zfcp_def.h"
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/**
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* struct zfcp_diag_header - general part of a diagnostic buffer.
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* @access_lock: lock protecting all the data in this buffer.
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* @updating: flag showing that an update for this buffer is currently running.
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* @incomplete: flag showing that the data in @buffer is incomplete.
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* @timestamp: time in jiffies when the data of this buffer was last captured.
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* @buffer: implementation-depending data of this buffer
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* @buffer_size: size of @buffer
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*/
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struct zfcp_diag_header {
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spinlock_t access_lock;
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/* Flags */
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u64 updating :1;
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u64 incomplete :1;
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unsigned long timestamp;
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void *buffer;
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size_t buffer_size;
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};
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/**
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* struct zfcp_diag_adapter - central storage for all diagnostics concerning an
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* adapter.
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* @port_data: data retrieved using exchange port data.
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* @port_data.header: header with metadata for the cache in @port_data.data.
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* @port_data.data: cached QTCB Bottom of command exchange port data.
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*/
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struct zfcp_diag_adapter {
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struct {
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struct zfcp_diag_header header;
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struct fsf_qtcb_bottom_port data;
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} port_data;
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};
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int zfcp_diag_adapter_setup(struct zfcp_adapter *const adapter);
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void zfcp_diag_adapter_free(struct zfcp_adapter *const adapter);
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void zfcp_diag_update_xdata(struct zfcp_diag_header *const hdr,
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const void *const data, const bool incomplete);
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#endif /* ZFCP_DIAG_H */
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@ -11,6 +11,7 @@
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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#include <linux/blktrace_api.h>
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#include <linux/jiffies.h>
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <scsi/fc/fc_els.h>
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#include "zfcp_dbf.h"
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#include "zfcp_qdio.h"
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#include "zfcp_reqlist.h"
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#include "zfcp_diag.h"
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/* timeout for FSF requests sent during scsi_eh: abort or FCP TMF */
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#define ZFCP_FSF_SCSI_ER_TIMEOUT (10*HZ)
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static void zfcp_fsf_exchange_port_data_handler(struct zfcp_fsf_req *req)
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{
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struct zfcp_diag_header *const diag_hdr =
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&req->adapter->diagnostics->port_data.header;
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struct fsf_qtcb *qtcb = req->qtcb;
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struct fsf_qtcb_bottom_port *bottom = &qtcb->bottom.port;
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if (req->status & ZFCP_STATUS_FSFREQ_ERROR)
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return;
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switch (qtcb->header.fsf_status) {
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case FSF_GOOD:
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/*
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* usually we wait with an update till the cache is too old,
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* but because we have the data available, update it anyway
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*/
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zfcp_diag_update_xdata(diag_hdr, bottom, false);
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zfcp_fsf_exchange_port_evaluate(req);
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break;
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case FSF_EXCHANGE_CONFIG_DATA_INCOMPLETE:
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zfcp_diag_update_xdata(diag_hdr, bottom, true);
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req->status |= ZFCP_STATUS_FSFREQ_XDATAINCOMPLETE;
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zfcp_fsf_exchange_port_evaluate(req);
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