net/batman-adv/log.c

   1 /* Copyright (C) 2010-2016  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/stat.h>
  35 #include <linux/stddef.h>
  36 #include <linux/types.h>
  37 #include <linux/uaccess.h>
  38 #include <linux/wait.h>
  39 #include <stdarg.h>
  40
  41 #define BATADV_LOG_BUFF_MASK (batadv_log_buff_len - 1)
  42
  43 static const int batadv_log_buff_len = BATADV_LOG_BUF_LEN;
  44
  45 static char *batadv_log_char_addr(struct batadv_priv_debug_log *debug_log,
  46                                   size_t idx)
  47 {
  48         return &debug_log->log_buff[idx & BATADV_LOG_BUFF_MASK];
  49 }
  50
  51 static void batadv_emit_log_char(struct batadv_priv_debug_log *debug_log,
  52                                  char c)
  53 {
  54         char *char_addr;
  55
  56         char_addr = batadv_log_char_addr(debug_log, debug_log->log_end);
  57         *char_addr = c;
  58         debug_log->log_end++;
  59
  60         if (debug_log->log_end - debug_log->log_start > batadv_log_buff_len)
  61                 debug_log->log_start = debug_log->log_end - batadv_log_buff_len;
  62 }
  63
  64 __printf(2, 3)
  65 static int batadv_fdebug_log(struct batadv_priv_debug_log *debug_log,
  66                              const char *fmt, ...)
  67 {
  68         va_list args;
  69         static char debug_log_buf[256];
  70         char *p;
  71
  72         if (!debug_log)
  73                 return 0;
  74
  75         spin_lock_bh(&debug_log->lock);
  76         va_start(args, fmt);
  77         vscnprintf(debug_log_buf, sizeof(debug_log_buf), fmt, args);
  78         va_end(args);
  79
  80         for (p = debug_log_buf; *p != 0; p++)
  81                 batadv_emit_log_char(debug_log, *p);
  82
  83         spin_unlock_bh(&debug_log->lock);
  84
  85         wake_up(&debug_log->queue_wait);
  86
  87         return 0;
  88 }
  89
  90 int batadv_debug_log(struct batadv_priv *bat_priv, const char *fmt, ...)
  91 {
  92         va_list args;
  93         char tmp_log_buf[256];
  94
  95         va_start(args, fmt);
  96         vscnprintf(tmp_log_buf, sizeof(tmp_log_buf), fmt, args);
  97         batadv_fdebug_log(bat_priv->debug_log, "[%10u] %s",
  98                           jiffies_to_msecs(jiffies), tmp_log_buf);
  99         va_end(args);
 100
 101         return 0;
 102 }
 103
 104 static int batadv_log_open(struct inode *inode, struct file *file)
 105 {
 106         if (!try_module_get(THIS_MODULE))
 107                 return -EBUSY;
 108
 109         nonseekable_open(inode, file);
 110         file->private_data = inode->i_private;
 111         return 0;
 112 }
 113
 114 static int batadv_log_release(struct inode *inode, struct file *file)
 115 {
 116         module_put(THIS_MODULE);
 117         return 0;
 118 }
 119
 120 static bool batadv_log_empty(struct batadv_priv_debug_log *debug_log)
 121 {
 122         return !(debug_log->log_start - debug_log->log_end);
 123 }
 124
 125 static ssize_t batadv_log_read(struct file *file, char __user *buf,
 126                                size_t count, loff_t *ppos)
 127 {
 128         struct batadv_priv *bat_priv = file->private_data;
 129         struct batadv_priv_debug_log *debug_log = bat_priv->debug_log;
 130         int error, i = 0;
 131         char *char_addr;
 132         char c;
 133
 134         if ((file->f_flags & O_NONBLOCK) && batadv_log_empty(debug_log))
 135                 return -EAGAIN;
 136
 137         if (!buf)
 138                 return -EINVAL;
 139
 140         if (count == 0)
 141                 return 0;
 142
 143         if (!access_ok(VERIFY_WRITE, buf, count))
 144                 return -EFAULT;
 145
 146         error = wait_event_interruptible(debug_log->queue_wait,
 147                                          (!batadv_log_empty(debug_log)));
 148
 149         if (error)
 150                 return error;
 151
 152         spin_lock_bh(&debug_log->lock);
 153
 154         while ((!error) && (i < count) &&
 155                (debug_log->log_start != debug_log->log_end)) {
 156                 char_addr = batadv_log_char_addr(debug_log,
 157                                                  debug_log->log_start);
 158                 c = *char_addr;
 159
 160                 debug_log->log_start++;
 161
 162                 spin_unlock_bh(&debug_log->lock);
 163
 164                 error = __put_user(c, buf);
 165
 166                 spin_lock_bh(&debug_log->lock);
 167
 168                 buf++;
 169                 i++;
 170         }
 171
 172         spin_unlock_bh(&debug_log->lock);
 173
 174         if (!error)
 175                 return i;
 176
 177         return error;
 178 }
 179
 180 static unsigned int batadv_log_poll(struct file *file, poll_table *wait)
 181 {
 182         struct batadv_priv *bat_priv = file->private_data;
 183         struct batadv_priv_debug_log *debug_log = bat_priv->debug_log;
 184
 185         poll_wait(file, &debug_log->queue_wait, wait);
 186
 187         if (!batadv_log_empty(debug_log))
 188                 return POLLIN | POLLRDNORM;
 189
 190         return 0;
 191 }
 192
 193 static const struct file_operations batadv_log_fops = {
 194         .open           = batadv_log_open,
 195         .release        = batadv_log_release,
 196         .read           = batadv_log_read,
 197         .poll           = batadv_log_poll,
 198         .llseek         = no_llseek,
 199 };
 200
 201 int batadv_debug_log_setup(struct batadv_priv *bat_priv)
 202 {
 203         struct dentry *d;
 204
 205         if (!bat_priv->debug_dir)
 206                 goto err;
 207
 208         bat_priv->debug_log = kzalloc(sizeof(*bat_priv->debug_log), GFP_ATOMIC);
 209         if (!bat_priv->debug_log)
 210                 goto err;
 211
 212         spin_lock_init(&bat_priv->debug_log->lock);
 213         init_waitqueue_head(&bat_priv->debug_log->queue_wait);
 214
 215         d = debugfs_create_file("log", S_IFREG | S_IRUSR,
 216                                 bat_priv->debug_dir, bat_priv,
 217                                 &batadv_log_fops);
 218         if (!d)
 219                 goto err;
 220
 221         return 0;
 222
 223 err:
 224         return -ENOMEM;
 225 }
 226
 227 void batadv_debug_log_cleanup(struct batadv_priv *bat_priv)
 228 {
 229         kfree(bat_priv->debug_log);
 230         bat_priv->debug_log = NULL;
 231 }