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/export.h>
  26 #include <linux/fcntl.h>
  27 #include <linux/fs.h>
  28 #include <linux/gfp.h>
  29 #include <linux/jiffies.h>
  30 #include <linux/kernel.h>
  31 #include <linux/module.h>
  32 #include <linux/poll.h>
  33 #include <linux/sched.h> /* for linux/wait.h */
  34 #include <linux/slab.h>
  35 #include <linux/spinlock.h>
  36 #include <linux/stddef.h>
  37 #include <linux/types.h>
  38 #include <linux/uaccess.h>
  39 #include <linux/wait.h>
  40 #include <stdarg.h>
  41
  42 #define BATADV_LOG_BUFF_MASK (batadv_log_buff_len - 1)
  43
  44 static const int batadv_log_buff_len = BATADV_LOG_BUF_LEN;
  45
  46 static char *batadv_log_char_addr(struct batadv_priv_debug_log *debug_log,
  47                                   size_t idx)
  48 {
  49         return &debug_log->log_buff[idx & BATADV_LOG_BUFF_MASK];
  50 }
  51
  52 static void batadv_emit_log_char(struct batadv_priv_debug_log *debug_log,
  53                                  char c)
  54 {
  55         char *char_addr;
  56
  57         char_addr = batadv_log_char_addr(debug_log, debug_log->log_end);
  58         *char_addr = c;
  59         debug_log->log_end++;
  60
  61         if (debug_log->log_end - debug_log->log_start > batadv_log_buff_len)
  62                 debug_log->log_start = debug_log->log_end - batadv_log_buff_len;
  63 }
  64
  65 __printf(2, 3)
  66 static int batadv_fdebug_log(struct batadv_priv_debug_log *debug_log,
  67                              const char *fmt, ...)
  68 {
  69         va_list args;
  70         static char debug_log_buf[256];
  71         char *p;
  72
  73         if (!debug_log)
  74                 return 0;
  75
  76         spin_lock_bh(&debug_log->lock);
  77         va_start(args, fmt);
  78         vscnprintf(debug_log_buf, sizeof(debug_log_buf), fmt, args);
  79         va_end(args);
  80
  81         for (p = debug_log_buf; *p != 0; p++)
  82                 batadv_emit_log_char(debug_log, *p);
  83
  84         spin_unlock_bh(&debug_log->lock);
  85
  86         wake_up(&debug_log->queue_wait);
  87
  88         return 0;
  89 }
  90
  91 /**
  92  * batadv_debug_log() - Add debug log entry
  93  * @bat_priv: the bat priv with all the soft interface information
  94  * @fmt: format string
  95  *
  96  * Return: 0 on success or negative error number in case of failure
  97  */
  98 int batadv_debug_log(struct batadv_priv *bat_priv, const char *fmt, ...)
  99 {
 100         va_list args;
 101         char tmp_log_buf[256];
 102
 103         va_start(args, fmt);
 104         vscnprintf(tmp_log_buf, sizeof(tmp_log_buf), fmt, args);
 105         batadv_fdebug_log(bat_priv->debug_log, "[%10u] %s",
 106                           jiffies_to_msecs(jiffies), tmp_log_buf);
 107         va_end(args);
 108
 109         return 0;
 110 }
 111
 112 static int batadv_log_open(struct inode *inode, struct file *file)
 113 {
 114         if (!try_module_get(THIS_MODULE))
 115                 return -EBUSY;
 116
 117         nonseekable_open(inode, file);
 118         file->private_data = inode->i_private;
 119         return 0;
 120 }
 121
 122 static int batadv_log_release(struct inode *inode, struct file *file)
 123 {
 124         module_put(THIS_MODULE);
 125         return 0;
 126 }
 127
 128 static bool batadv_log_empty(struct batadv_priv_debug_log *debug_log)
 129 {
 130         return !(debug_log->log_start - debug_log->log_end);
 131 }
 132
 133 static ssize_t batadv_log_read(struct file *file, char __user *buf,
 134                                size_t count, loff_t *ppos)
 135 {
 136         struct batadv_priv *bat_priv = file->private_data;
 137         struct batadv_priv_debug_log *debug_log = bat_priv->debug_log;
 138         int error, i = 0;
 139         char *char_addr;
 140         char c;
 141
 142         if ((file->f_flags & O_NONBLOCK) && batadv_log_empty(debug_log))
 143                 return -EAGAIN;
 144
 145         if (!buf)
 146                 return -EINVAL;
 147
 148         if (count == 0)
 149                 return 0;
 150
 151         if (!access_ok(VERIFY_WRITE, buf, count))
 152                 return -EFAULT;
 153
 154         error = wait_event_interruptible(debug_log->queue_wait,
 155                                          (!batadv_log_empty(debug_log)));
 156
 157         if (error)
 158                 return error;
 159
 160         spin_lock_bh(&debug_log->lock);
 161
 162         while ((!error) && (i < count) &&
 163                (debug_log->log_start != debug_log->log_end)) {
 164                 char_addr = batadv_log_char_addr(debug_log,
 165                                                  debug_log->log_start);
 166                 c = *char_addr;
 167
 168                 debug_log->log_start++;
 169
 170                 spin_unlock_bh(&debug_log->lock);
 171
 172                 error = __put_user(c, buf);
 173
 174                 spin_lock_bh(&debug_log->lock);
 175
 176                 buf++;
 177                 i++;
 178         }
 179
 180         spin_unlock_bh(&debug_log->lock);
 181
 182         if (!error)
 183                 return i;
 184
 185         return error;
 186 }
 187
 188 static __poll_t batadv_log_poll(struct file *file, poll_table *wait)
 189 {
 190         struct batadv_priv *bat_priv = file->private_data;
 191         struct batadv_priv_debug_log *debug_log = bat_priv->debug_log;
 192
 193         poll_wait(file, &debug_log->queue_wait, wait);
 194
 195         if (!batadv_log_empty(debug_log))
 196                 return EPOLLIN | EPOLLRDNORM;
 197
 198         return 0;
 199 }
 200
 201 static const struct file_operations batadv_log_fops = {
 202         .open           = batadv_log_open,
 203         .release        = batadv_log_release,
 204         .read           = batadv_log_read,
 205         .poll           = batadv_log_poll,
 206         .llseek         = no_llseek,
 207 };
 208
 209 /**
 210  * batadv_debug_log_setup() - Initialize debug log
 211  * @bat_priv: the bat priv with all the soft interface information
 212  *
 213  * Return: 0 on success or negative error number in case of failure
 214  */
 215 int batadv_debug_log_setup(struct batadv_priv *bat_priv)
 216 {
 217         struct dentry *d;
 218
 219         if (!bat_priv->debug_dir)
 220                 goto err;
 221
 222         bat_priv->debug_log = kzalloc(sizeof(*bat_priv->debug_log), GFP_ATOMIC);
 223         if (!bat_priv->debug_log)
 224                 goto err;
 225
 226         spin_lock_init(&bat_priv->debug_log->lock);
 227         init_waitqueue_head(&bat_priv->debug_log->queue_wait);
 228
 229         d = debugfs_create_file("log", 0400, bat_priv->debug_dir, bat_priv,
 230                                 &batadv_log_fops);
 231         if (!d)
 232                 goto err;
 233
 234         return 0;
 235
 236 err:
 237         return -ENOMEM;
 238 }
 239
 240 /**
 241  * batadv_debug_log_cleanup() - Destroy debug log
 242  * @bat_priv: the bat priv with all the soft interface information
 243  */
 244 void batadv_debug_log_cleanup(struct batadv_priv *bat_priv)
 245 {
 246         kfree(bat_priv->debug_log);
 247         bat_priv->debug_log = NULL;
 248 }