From 7e418833e68948cb9ed15262889173b7db2960cb Mon Sep 17 00:00:00 2001 From: Benjamin Block Date: Fri, 25 Oct 2019 18:12:44 +0200 Subject: 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 Signed-off-by: Benjamin Block Signed-off-by: Martin K. Petersen --- 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 (limited to 'drivers/s390/scsi') 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..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); 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..fa1b25f3ec3c --- /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 +#include +#include +#include +#include + +#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..2a933326b6e4 --- /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 + +#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 d8f0e446fe13..883bbfd67a62 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 +#include #include #include #include @@ -19,6 +20,7 @@ #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) @@ -655,16 +657,26 @@ 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); -- cgit v1.2.3