net/batman-adv/log.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (C) 2010-2017  B.A.T.M.A.N. contributors:
   3  *
   4  * Marek Lindner
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of version 2 of the GNU General Public
   8  * License as published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  13  * General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include "log.h"
  20 #include "main.h"
  21
  22 #include <linux/compiler.h>
  23 #include <linux/debugfs.h>
  24 #include <linux/errno.h>
  25 #include <linux/eventpoll.h>
  26 #include <linux/export.h>
  27 #include <linux/fcntl.h>
  28 #include <linux/fs.h>
  29 #include <linux/gfp.h>
  30 #include <linux/jiffies.h>
  31 #include <linux/kernel.h>
  32 #include <linux/module.h>
  33 #include <linux/poll.h>
  34 #include <linux/sched.h> /* for linux/wait.h */
  35 #include <linux/slab.h>
  36 #include <linux/spinlock.h>
  37 #include <linux/stddef.h>
  38 #include <linux/types.h>
  39 #include <linux/uaccess.h>
  40 #include <linux/wait.h>
  41 #include <stdarg.h>
  42
  43 #define BATADV_LOG_BUFF_MASK (batadv_log_buff_len - 1)
  44
  45 static const int batadv_log_buff_len = BATADV_LOG_BUF_LEN;
  46
  47 static char *batadv_log_char_addr(struct batadv_priv_debug_log *debug_log,
  48                                   size_t idx)
  49 {
  50         return &debug_log->log_buff[idx & BATADV_LOG_BUFF_MASK];
  51 }
  52
  53 static void batadv_emit_log_char(struct batadv_priv_debug_log *debug_log,
  54                                  char c)
  55 {
  56         char *char_addr;
  57
  58         char_addr = batadv_log_char_addr(debug_log, debug_log->log_end);
  59         *char_addr = c;
  60         debug_log->log_end++;
  61
  62         if (debug_log->log_end - debug_log->log_start > batadv_log_buff_len)
  63                 debug_log->log_start = debug_log->log_end - batadv_log_buff_len;
  64 }
  65
  66 __printf(2, 3)
  67 static int batadv_fdebug_log(struct batadv_priv_debug_log *debug_log,
  68                              const char *fmt, ...)
  69 {
  70         va_list args;
  71         static char debug_log_buf[256];
  72         char *p;
  73
  74         if (!debug_log)
  75                 return 0;
  76
  77         spin_lock_bh(&debug_log->lock);
  78         va_start(args, fmt);
  79         vscnprintf(debug_log_buf, sizeof(debug_log_buf), fmt, args);
  80         va_end(args);
  81
  82         for (p = debug_log_buf; *p != 0; p++)
  83                 batadv_emit_log_char(debug_log, *p);
  84
  85         spin_unlock_bh(&debug_log->lock);
  86
  87         wake_up(&debug_log->queue_wait);
  88
  89         return 0;
  90 }
  91
  92 /**
  93  * batadv_debug_log() - Add debug log entry
  94  * @bat_priv: the bat priv with all the soft interface information
  95  * @fmt: format string
  96  *
  97  * Return: 0 on success or negative error number in case of failure
  98  */
  99 int batadv_debug_log(struct batadv_priv *bat_priv, const char *fmt, ...)
 100 {
 101         va_list args;
 102         char tmp_log_buf[256];
 103
 104         va_start(args, fmt);
 105         vscnprintf(tmp_log_buf, sizeof(tmp_log_buf), fmt, args);
 106         batadv_fdebug_log(bat_priv->debug_log, "[%10u] %s",
 107                           jiffies_to_msecs(jiffies), tmp_log_buf);
 108         va_end(args);
 109
 110         return 0;
 111 }
 112
 113 static int batadv_log_open(struct inode *inode, struct file *file)
 114 {
 115         if (!try_module_get(THIS_MODULE))
 116                 return -EBUSY;
 117
 118         nonseekable_open(inode, file);
 119         file->private_data = inode->i_private;
 120         return 0;
 121 }
 122
 123 static int batadv_log_release(struct inode *inode, struct file *file)
 124 {
 125         module_put(THIS_MODULE);
 126         return 0;
 127 }
 128
 129 static bool batadv_log_empty(struct batadv_priv_debug_log *debug_log)
 130 {
 131         return !(debug_log->log_start - debug_log->log_end);
 132 }
 133
 134 static ssize_t batadv_log_read(struct file *file, char __user *buf,
 135                                size_t count, loff_t *ppos)
 136 {
 137         struct batadv_priv *bat_priv = file->private_data;
 138         struct batadv_priv_debug_log *debug_log = bat_priv->debug_log;
 139         int error, i = 0;
 140         char *char_addr;
 141         char c;
 142
 143         if ((file->f_flags & O_NONBLOCK) && batadv_log_empty(debug_log))
 144                 return -EAGAIN;
 145
 146         if (!buf)
 147                 return -EINVAL;
 148
 149         if (count == 0)
 150                 return 0;
 151
 152         if (!access_ok(VERIFY_WRITE, buf, count))
 153                 return -EFAULT;
 154
 155         error = wait_event_interruptible(debug_log->queue_wait,
 156                                          (!batadv_log_empty(debug_log)));
 157
 158         if (error)
 159                 return error;
 160
 161         spin_lock_bh(&debug_log->lock);
 162
 163         while ((!error) && (i < count) &&
 164                (debug_log->log_start != debug_log->log_end)) {
 165                 char_addr = batadv_log_char_addr(debug_log,
 166                                                  debug_log->log_start);
 167                 c = *char_addr;
 168
 169                 debug_log->log_start++;
 170
 171                 spin_unlock_bh(&debug_log->lock);
 172
 173                 error = __put_user(c, buf);
 174
 175                 spin_lock_bh(&debug_log->lock);
 176
 177                 buf++;
 178                 i++;
 179         }
 180
 181         spin_unlock_bh(&debug_log->lock);
 182
 183         if (!error)
 184                 return i;
 185
 186         return error;
 187 }
 188
 189 static __poll_t batadv_log_poll(struct file *file, poll_table *wait)
 190 {
 191         struct batadv_priv *bat_priv = file->private_data;
 192         struct batadv_priv_debug_log *debug_log = bat_priv->debug_log;
 193
 194         poll_wait(file, &debug_log->queue_wait, wait);
 195
 196         if (!batadv_log_empty(debug_log))
 197                 return EPOLLIN | EPOLLRDNORM;
 198
 199         return 0;
 200 }
 201
 202 static const struct file_operations batadv_log_fops = {
 203         .open           = batadv_log_open,
 204         .release        = batadv_log_release,
 205         .read           = batadv_log_read,
 206         .poll           = batadv_log_poll,
 207         .llseek         = no_llseek,
 208 };
 209
 210 /**
 211  * batadv_debug_log_setup() - Initialize debug log
 212  * @bat_priv: the bat priv with all the soft interface information
 213  *
 214  * Return: 0 on success or negative error number in case of failure
 215  */
 216 int batadv_debug_log_setup(struct batadv_priv *bat_priv)
 217 {
 218         struct dentry *d;
 219
 220         if (!bat_priv->debug_dir)
 221                 goto err;
 222
 223         bat_priv->debug_log = kzalloc(sizeof(*bat_priv->debug_log), GFP_ATOMIC);
 224         if (!bat_priv->debug_log)
 225                 goto err;
 226
 227         spin_lock_init(&bat_priv->debug_log->lock);
 228         init_waitqueue_head(&bat_priv->debug_log->queue_wait);
 229
 230         d = debugfs_create_file("log", 0400, bat_priv->debug_dir, bat_priv,
 231                                 &batadv_log_fops);
 232         if (!d)
 233                 goto err;
 234
 235         return 0;
 236
 237 err:
 238         return -ENOMEM;
 239 }
 240
 241 /**
 242  * batadv_debug_log_cleanup() - Destroy debug log
 243  * @bat_priv: the bat priv with all the soft interface information
 244  */
 245 void batadv_debug_log_cleanup(struct batadv_priv *bat_priv)
 246 {
 247         kfree(bat_priv->debug_log);
 248         bat_priv->debug_log = NULL;
 249 }