drivers/s390/scsi/zfcp_diag.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * zfcp device driver
   4  *
   5  * Functions to handle diagnostics.
   6  *
   7  * Copyright IBM Corp. 2018
   8  */
   9
  10 #include <linux/spinlock.h>
  11 #include <linux/jiffies.h>
  12 #include <linux/string.h>
  13 #include <linux/errno.h>
  14 #include <linux/slab.h>
  15
  16 #include "zfcp_diag.h"
  17 #include "zfcp_ext.h"
  18 #include "zfcp_def.h"
  19
  20 static DECLARE_WAIT_QUEUE_HEAD(__zfcp_diag_publish_wait);
  21
  22 /**
  23  * zfcp_diag_adapter_setup() - Setup storage for adapter diagnostics.
  24  * @adapter: the adapter to setup diagnostics for.
  25  *
  26  * Creates the data-structures to store the diagnostics for an adapter. This
  27  * overwrites whatever was stored before at &zfcp_adapter->diagnostics!
  28  *
  29  * Return:
  30  * * 0       - Everyting is OK
  31  * * -ENOMEM - Could not allocate all/parts of the data-structures;
  32  *             &zfcp_adapter->diagnostics remains unchanged
  33  */
  34 int zfcp_diag_adapter_setup(struct zfcp_adapter *const adapter)
  35 {
  36         struct zfcp_diag_adapter *diag;
  37         struct zfcp_diag_header *hdr;
  38
  39         diag = kzalloc(sizeof(*diag), GFP_KERNEL);
  40         if (diag == NULL)
  41                 return -ENOMEM;
  42
  43         diag->max_age = (5 * 1000); /* default value: 5 s */
  44
  45         /* setup header for port_data */
  46         hdr = &diag->port_data.header;
  47
  48         spin_lock_init(&hdr->access_lock);
  49         hdr->buffer = &diag->port_data.data;
  50         hdr->buffer_size = sizeof(diag->port_data.data);
  51         /* set the timestamp so that the first test on age will always fail */
  52         hdr->timestamp = jiffies - msecs_to_jiffies(diag->max_age);
  53
  54         /* setup header for config_data */
  55         hdr = &diag->config_data.header;
  56
  57         spin_lock_init(&hdr->access_lock);
  58         hdr->buffer = &diag->config_data.data;
  59         hdr->buffer_size = sizeof(diag->config_data.data);
  60         /* set the timestamp so that the first test on age will always fail */
  61         hdr->timestamp = jiffies - msecs_to_jiffies(diag->max_age);
  62
  63         adapter->diagnostics = diag;
  64         return 0;
  65 }
  66
  67 /**
  68  * zfcp_diag_adapter_free() - Frees all adapter diagnostics allocations.
  69  * @adapter: the adapter whose diagnostic structures should be freed.
  70  *
  71  * Frees all data-structures in the given adapter that store diagnostics
  72  * information. Can savely be called with partially setup diagnostics.
  73  */
  74 void zfcp_diag_adapter_free(struct zfcp_adapter *const adapter)
  75 {
  76         kfree(adapter->diagnostics);
  77         adapter->diagnostics = NULL;
  78 }
  79
  80 /**
  81  * zfcp_diag_update_xdata() - Update a diagnostics buffer.
  82  * @hdr: the meta data to update.
  83  * @data: data to use for the update.
  84  * @incomplete: flag stating whether the data in @data is incomplete.
  85  */
  86 void zfcp_diag_update_xdata(struct zfcp_diag_header *const hdr,
  87                             const void *const data, const bool incomplete)
  88 {
  89         const unsigned long capture_timestamp = jiffies;
  90         unsigned long flags;
  91
  92         spin_lock_irqsave(&hdr->access_lock, flags);
  93
  94         /* make sure we never go into the past with an update */
  95         if (!time_after_eq(capture_timestamp, hdr->timestamp))
  96                 goto out;
  97
  98         hdr->timestamp = capture_timestamp;
  99         hdr->incomplete = incomplete;
 100         memcpy(hdr->buffer, data, hdr->buffer_size);
 101 out:
 102         spin_unlock_irqrestore(&hdr->access_lock, flags);
 103 }
 104
 105 /**
 106  * zfcp_diag_update_port_data_buffer() - Implementation of
 107  *                                       &typedef zfcp_diag_update_buffer_func
 108  *                                       to collect and update Port Data.
 109  * @adapter: Adapter to collect Port Data from.
 110  *
 111  * This call is SYNCHRONOUS ! It blocks till the respective command has
 112  * finished completely, or has failed in some way.
 113  *
 114  * Return:
 115  * * 0          - Successfully retrieved new Diagnostics and Updated the buffer;
 116  *                this also includes cases where data was retrieved, but
 117  *                incomplete; you'll have to check the flag ``incomplete``
 118  *                of &struct zfcp_diag_header.
 119  * * see zfcp_fsf_exchange_port_data_sync() for possible error-codes (
 120  *   excluding -EAGAIN)
 121  */
 122 int zfcp_diag_update_port_data_buffer(struct zfcp_adapter *const adapter)
 123 {
 124         int rc;
 125
 126         rc = zfcp_fsf_exchange_port_data_sync(adapter->qdio, NULL);
 127         if (rc == -EAGAIN)
 128                 rc = 0; /* signaling incomplete via struct zfcp_diag_header */
 129
 130         /* buffer-data was updated in zfcp_fsf_exchange_port_data_handler() */
 131
 132         return rc;
 133 }
 134
 135 /**
 136  * zfcp_diag_update_config_data_buffer() - Implementation of
 137  *                                         &typedef zfcp_diag_update_buffer_func
 138  *                                         to collect and update Config Data.
 139  * @adapter: Adapter to collect Config Data from.
 140  *
 141  * This call is SYNCHRONOUS ! It blocks till the respective command has
 142  * finished completely, or has failed in some way.
 143  *
 144  * Return:
 145  * * 0          - Successfully retrieved new Diagnostics and Updated the buffer;
 146  *                this also includes cases where data was retrieved, but
 147  *                incomplete; you'll have to check the flag ``incomplete``
 148  *                of &struct zfcp_diag_header.
 149  * * see zfcp_fsf_exchange_config_data_sync() for possible error-codes (
 150  *   excluding -EAGAIN)
 151  */
 152 int zfcp_diag_update_config_data_buffer(struct zfcp_adapter *const adapter)
 153 {
 154         int rc;
 155
 156         rc = zfcp_fsf_exchange_config_data_sync(adapter->qdio, NULL);
 157         if (rc == -EAGAIN)
 158                 rc = 0; /* signaling incomplete via struct zfcp_diag_header */
 159
 160         /* buffer-data was updated in zfcp_fsf_exchange_config_data_handler() */
 161
 162         return rc;
 163 }
 164
 165 static int __zfcp_diag_update_buffer(struct zfcp_adapter *const adapter,
 166                                      struct zfcp_diag_header *const hdr,
 167                                      zfcp_diag_update_buffer_func buffer_update,
 168                                      unsigned long *const flags)
 169         __must_hold(hdr->access_lock)
 170 {
 171         int rc;
 172
 173         if (hdr->updating == 1) {
 174                 rc = wait_event_interruptible_lock_irq(__zfcp_diag_publish_wait,
 175                                                        hdr->updating == 0,
 176                                                        hdr->access_lock);
 177                 rc = (rc == 0 ? -EAGAIN : -EINTR);
 178         } else {
 179                 hdr->updating = 1;
 180                 spin_unlock_irqrestore(&hdr->access_lock, *flags);
 181
 182                 /* unlocked, because update function sleeps */
 183                 rc = buffer_update(adapter);
 184
 185                 spin_lock_irqsave(&hdr->access_lock, *flags);
 186                 hdr->updating = 0;
 187
 188                 /*
 189                  * every thread waiting here went via an interruptible wait,
 190                  * so its fine to only wake those
 191                  */
 192                 wake_up_interruptible_all(&__zfcp_diag_publish_wait);
 193         }
 194
 195         return rc;
 196 }
 197
 198 static bool
 199 __zfcp_diag_test_buffer_age_isfresh(const struct zfcp_diag_adapter *const diag,
 200                                     const struct zfcp_diag_header *const hdr)
 201         __must_hold(hdr->access_lock)
 202 {
 203         const unsigned long now = jiffies;
 204
 205         /*
 206          * Should not happen (data is from the future).. if it does, still
 207          * signal that it needs refresh
 208          */
 209         if (!time_after_eq(now, hdr->timestamp))
 210                 return false;
 211
 212         if (jiffies_to_msecs(now - hdr->timestamp) >= diag->max_age)
 213                 return false;
 214
 215         return true;
 216 }
 217
 218 /**
 219  * zfcp_diag_update_buffer_limited() - Collect diagnostics and update a
 220  *                                     diagnostics buffer rate limited.
 221  * @adapter: Adapter to collect the diagnostics from.
 222  * @hdr: buffer-header for which to update with the collected diagnostics.
 223  * @buffer_update: Specific implementation for collecting and updating.
 224  *
 225  * This function will cause an update of the given @hdr by calling the also
 226  * given @buffer_update function. If called by multiple sources at the same
 227  * time, it will synchornize the update by only allowing one source to call
 228  * @buffer_update and the others to wait for that source to complete instead
 229  * (the wait is interruptible).
 230  *
 231  * Additionally this version is rate-limited and will only exit if either the
 232  * buffer is fresh enough (within the limit) - it will do nothing if the buffer
 233  * is fresh enough to begin with -, or if the source/thread that started this
 234  * update is the one that made the update (to prevent endless loops).
 235  *
 236  * Return:
 237  * * 0          - If the update was successfully published and/or the buffer is
 238  *                fresh enough
 239  * * -EINTR     - If the thread went into the wait-state and was interrupted
 240  * * whatever @buffer_update returns
 241  */
 242 int zfcp_diag_update_buffer_limited(struct zfcp_adapter *const adapter,
 243                                     struct zfcp_diag_header *const hdr,
 244                                     zfcp_diag_update_buffer_func buffer_update)
 245 {
 246         unsigned long flags;
 247         int rc;
 248
 249         spin_lock_irqsave(&hdr->access_lock, flags);
 250
 251         for (rc = 0;
 252              !__zfcp_diag_test_buffer_age_isfresh(adapter->diagnostics, hdr);
 253              rc = 0) {
 254                 rc = __zfcp_diag_update_buffer(adapter, hdr, buffer_update,
 255                                                &flags);
 256                 if (rc != -EAGAIN)
 257                         break;
 258         }
 259
 260         spin_unlock_irqrestore(&hdr->access_lock, flags);
 261
 262         return rc;
 263 }