linux/net/tipc/log.c
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   1/*
   2 * net/tipc/log.c: TIPC print buffer routines for debugging
   3 *
   4 * Copyright (c) 1996-2006, Ericsson AB
   5 * Copyright (c) 2005-2007, Wind River Systems
   6 * All rights reserved.
   7 *
   8 * Redistribution and use in source and binary forms, with or without
   9 * modification, are permitted provided that the following conditions are met:
  10 *
  11 * 1. Redistributions of source code must retain the above copyright
  12 *    notice, this list of conditions and the following disclaimer.
  13 * 2. Redistributions in binary form must reproduce the above copyright
  14 *    notice, this list of conditions and the following disclaimer in the
  15 *    documentation and/or other materials provided with the distribution.
  16 * 3. Neither the names of the copyright holders nor the names of its
  17 *    contributors may be used to endorse or promote products derived from
  18 *    this software without specific prior written permission.
  19 *
  20 * Alternatively, this software may be distributed under the terms of the
  21 * GNU General Public License ("GPL") version 2 as published by the Free
  22 * Software Foundation.
  23 *
  24 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  25 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  28 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  29 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  30 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  31 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  32 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  33 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  34 * POSSIBILITY OF SUCH DAMAGE.
  35 */
  36
  37#include "core.h"
  38#include "config.h"
  39#include "log.h"
  40
  41/*
  42 * TIPC pre-defines the following print buffers:
  43 *
  44 * TIPC_NULL : null buffer (i.e. print nowhere)
  45 * TIPC_CONS : system console
  46 * TIPC_LOG  : TIPC log buffer
  47 *
  48 * Additional user-defined print buffers are also permitted.
  49 */
  50
  51static struct print_buf null_buf = { NULL, 0, NULL, 0 };
  52struct print_buf *const TIPC_NULL = &null_buf;
  53
  54static struct print_buf cons_buf = { NULL, 0, NULL, 1 };
  55struct print_buf *const TIPC_CONS = &cons_buf;
  56
  57static struct print_buf log_buf = { NULL, 0, NULL, 1 };
  58struct print_buf *const TIPC_LOG = &log_buf;
  59
  60/*
  61 * Locking policy when using print buffers.
  62 *
  63 * 1) tipc_printf() uses 'print_lock' to protect against concurrent access to
  64 * 'print_string' when writing to a print buffer. This also protects against
  65 * concurrent writes to the print buffer being written to.
  66 *
  67 * 2) tipc_log_XXX() leverages the aforementioned use of 'print_lock' to
  68 * protect against all types of concurrent operations on their associated
  69 * print buffer (not just write operations).
  70 *
  71 * Note: All routines of the form tipc_printbuf_XXX() are lock-free, and rely
  72 * on the caller to prevent simultaneous use of the print buffer(s) being
  73 * manipulated.
  74 */
  75
  76static char print_string[TIPC_PB_MAX_STR];
  77static DEFINE_SPINLOCK(print_lock);
  78
  79static void tipc_printbuf_move(struct print_buf *pb_to,
  80                               struct print_buf *pb_from);
  81
  82#define FORMAT(PTR, LEN, FMT) \
  83{\
  84        va_list args;\
  85        va_start(args, FMT);\
  86        LEN = vsprintf(PTR, FMT, args);\
  87        va_end(args);\
  88        *(PTR + LEN) = '\0';\
  89}
  90
  91/**
  92 * tipc_printbuf_init - initialize print buffer to empty
  93 * @pb: pointer to print buffer structure
  94 * @raw: pointer to character array used by print buffer
  95 * @size: size of character array
  96 *
  97 * Note: If the character array is too small (or absent), the print buffer
  98 * becomes a null device that discards anything written to it.
  99 */
 100
 101void tipc_printbuf_init(struct print_buf *pb, char *raw, u32 size)
 102{
 103        pb->buf = raw;
 104        pb->crs = raw;
 105        pb->size = size;
 106        pb->echo = 0;
 107
 108        if (size < TIPC_PB_MIN_SIZE) {
 109                pb->buf = NULL;
 110        } else if (raw) {
 111                pb->buf[0] = 0;
 112                pb->buf[size - 1] = ~0;
 113        }
 114}
 115
 116/**
 117 * tipc_printbuf_reset - reinitialize print buffer to empty state
 118 * @pb: pointer to print buffer structure
 119 */
 120
 121static void tipc_printbuf_reset(struct print_buf *pb)
 122{
 123        if (pb->buf) {
 124                pb->crs = pb->buf;
 125                pb->buf[0] = 0;
 126                pb->buf[pb->size - 1] = ~0;
 127        }
 128}
 129
 130/**
 131 * tipc_printbuf_empty - test if print buffer is in empty state
 132 * @pb: pointer to print buffer structure
 133 *
 134 * Returns non-zero if print buffer is empty.
 135 */
 136
 137static int tipc_printbuf_empty(struct print_buf *pb)
 138{
 139        return !pb->buf || (pb->crs == pb->buf);
 140}
 141
 142/**
 143 * tipc_printbuf_validate - check for print buffer overflow
 144 * @pb: pointer to print buffer structure
 145 *
 146 * Verifies that a print buffer has captured all data written to it.
 147 * If data has been lost, linearize buffer and prepend an error message
 148 *
 149 * Returns length of print buffer data string (including trailing NUL)
 150 */
 151
 152int tipc_printbuf_validate(struct print_buf *pb)
 153{
 154        char *err = "\n\n*** PRINT BUFFER OVERFLOW ***\n\n";
 155        char *cp_buf;
 156        struct print_buf cb;
 157
 158        if (!pb->buf)
 159                return 0;
 160
 161        if (pb->buf[pb->size - 1] == 0) {
 162                cp_buf = kmalloc(pb->size, GFP_ATOMIC);
 163                if (cp_buf) {
 164                        tipc_printbuf_init(&cb, cp_buf, pb->size);
 165                        tipc_printbuf_move(&cb, pb);
 166                        tipc_printbuf_move(pb, &cb);
 167                        kfree(cp_buf);
 168                        memcpy(pb->buf, err, strlen(err));
 169                } else {
 170                        tipc_printbuf_reset(pb);
 171                        tipc_printf(pb, err);
 172                }
 173        }
 174        return pb->crs - pb->buf + 1;
 175}
 176
 177/**
 178 * tipc_printbuf_move - move print buffer contents to another print buffer
 179 * @pb_to: pointer to destination print buffer structure
 180 * @pb_from: pointer to source print buffer structure
 181 *
 182 * Current contents of destination print buffer (if any) are discarded.
 183 * Source print buffer becomes empty if a successful move occurs.
 184 */
 185
 186static void tipc_printbuf_move(struct print_buf *pb_to,
 187                               struct print_buf *pb_from)
 188{
 189        int len;
 190
 191        /* Handle the cases where contents can't be moved */
 192
 193        if (!pb_to->buf)
 194                return;
 195
 196        if (!pb_from->buf) {
 197                tipc_printbuf_reset(pb_to);
 198                return;
 199        }
 200
 201        if (pb_to->size < pb_from->size) {
 202                strcpy(pb_to->buf, "*** PRINT BUFFER MOVE ERROR ***");
 203                pb_to->buf[pb_to->size - 1] = ~0;
 204                pb_to->crs = strchr(pb_to->buf, 0);
 205                return;
 206        }
 207
 208        /* Copy data from char after cursor to end (if used) */
 209
 210        len = pb_from->buf + pb_from->size - pb_from->crs - 2;
 211        if ((pb_from->buf[pb_from->size - 1] == 0) && (len > 0)) {
 212                strcpy(pb_to->buf, pb_from->crs + 1);
 213                pb_to->crs = pb_to->buf + len;
 214        } else
 215                pb_to->crs = pb_to->buf;
 216
 217        /* Copy data from start to cursor (always) */
 218
 219        len = pb_from->crs - pb_from->buf;
 220        strcpy(pb_to->crs, pb_from->buf);
 221        pb_to->crs += len;
 222
 223        tipc_printbuf_reset(pb_from);
 224}
 225
 226/**
 227 * tipc_printf - append formatted output to print buffer
 228 * @pb: pointer to print buffer
 229 * @fmt: formatted info to be printed
 230 */
 231
 232void tipc_printf(struct print_buf *pb, const char *fmt, ...)
 233{
 234        int chars_to_add;
 235        int chars_left;
 236        char save_char;
 237
 238        spin_lock_bh(&print_lock);
 239
 240        FORMAT(print_string, chars_to_add, fmt);
 241        if (chars_to_add >= TIPC_PB_MAX_STR)
 242                strcpy(print_string, "*** PRINT BUFFER STRING TOO LONG ***");
 243
 244        if (pb->buf) {
 245                chars_left = pb->buf + pb->size - pb->crs - 1;
 246                if (chars_to_add <= chars_left) {
 247                        strcpy(pb->crs, print_string);
 248                        pb->crs += chars_to_add;
 249                } else if (chars_to_add >= (pb->size - 1)) {
 250                        strcpy(pb->buf, print_string + chars_to_add + 1
 251                               - pb->size);
 252                        pb->crs = pb->buf + pb->size - 1;
 253                } else {
 254                        strcpy(pb->buf, print_string + chars_left);
 255                        save_char = print_string[chars_left];
 256                        print_string[chars_left] = 0;
 257                        strcpy(pb->crs, print_string);
 258                        print_string[chars_left] = save_char;
 259                        pb->crs = pb->buf + chars_to_add - chars_left;
 260                }
 261        }
 262
 263        if (pb->echo)
 264                printk("%s", print_string);
 265
 266        spin_unlock_bh(&print_lock);
 267}
 268
 269/**
 270 * tipc_log_resize - change the size of the TIPC log buffer
 271 * @log_size: print buffer size to use
 272 */
 273
 274int tipc_log_resize(int log_size)
 275{
 276        int res = 0;
 277
 278        spin_lock_bh(&print_lock);
 279        kfree(TIPC_LOG->buf);
 280        TIPC_LOG->buf = NULL;
 281        if (log_size) {
 282                if (log_size < TIPC_PB_MIN_SIZE)
 283                        log_size = TIPC_PB_MIN_SIZE;
 284                res = TIPC_LOG->echo;
 285                tipc_printbuf_init(TIPC_LOG, kmalloc(log_size, GFP_ATOMIC),
 286                                   log_size);
 287                TIPC_LOG->echo = res;
 288                res = !TIPC_LOG->buf;
 289        }
 290        spin_unlock_bh(&print_lock);
 291
 292        return res;
 293}
 294
 295/**
 296 * tipc_log_resize_cmd - reconfigure size of TIPC log buffer
 297 */
 298
 299struct sk_buff *tipc_log_resize_cmd(const void *req_tlv_area, int req_tlv_space)
 300{
 301        u32 value;
 302
 303        if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_UNSIGNED))
 304                return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);
 305
 306        value = ntohl(*(__be32 *)TLV_DATA(req_tlv_area));
 307        if (value != delimit(value, 0, 32768))
 308                return tipc_cfg_reply_error_string(TIPC_CFG_INVALID_VALUE
 309                                                   " (log size must be 0-32768)");
 310        if (tipc_log_resize(value))
 311                return tipc_cfg_reply_error_string(
 312                        "unable to create specified log (log size is now 0)");
 313        return tipc_cfg_reply_none();
 314}
 315
 316/**
 317 * tipc_log_dump - capture TIPC log buffer contents in configuration message
 318 */
 319
 320struct sk_buff *tipc_log_dump(void)
 321{
 322        struct sk_buff *reply;
 323
 324        spin_lock_bh(&print_lock);
 325        if (!TIPC_LOG->buf) {
 326                spin_unlock_bh(&print_lock);
 327                reply = tipc_cfg_reply_ultra_string("log not activated\n");
 328        } else if (tipc_printbuf_empty(TIPC_LOG)) {
 329                spin_unlock_bh(&print_lock);
 330                reply = tipc_cfg_reply_ultra_string("log is empty\n");
 331        } else {
 332                struct tlv_desc *rep_tlv;
 333                struct print_buf pb;
 334                int str_len;
 335
 336                str_len = min(TIPC_LOG->size, 32768u);
 337                spin_unlock_bh(&print_lock);
 338                reply = tipc_cfg_reply_alloc(TLV_SPACE(str_len));
 339                if (reply) {
 340                        rep_tlv = (struct tlv_desc *)reply->data;
 341                        tipc_printbuf_init(&pb, TLV_DATA(rep_tlv), str_len);
 342                        spin_lock_bh(&print_lock);
 343                        tipc_printbuf_move(&pb, TIPC_LOG);
 344                        spin_unlock_bh(&print_lock);
 345                        str_len = strlen(TLV_DATA(rep_tlv)) + 1;
 346                        skb_put(reply, TLV_SPACE(str_len));
 347                        TLV_SET(rep_tlv, TIPC_TLV_ULTRA_STRING, NULL, str_len);
 348                }
 349        }
 350        return reply;
 351}
 352