net/batman-adv/log.c

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