GNU Linux-libre 4.14.266-gnu1
[releases.git] / 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         .owner          = THIS_MODULE,
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", 0400, bat_priv->debug_dir, bat_priv,
216                                 &batadv_log_fops);
217         if (!d)
218                 goto err;
219
220         return 0;
221
222 err:
223         return -ENOMEM;
224 }
225
226 void batadv_debug_log_cleanup(struct batadv_priv *bat_priv)
227 {
228         kfree(bat_priv->debug_log);
229         bat_priv->debug_log = NULL;
230 }