drivers/scsi/fnic/fnic_debugfs.c

   1 /*
   2  * Copyright 2012 Cisco Systems, Inc.  All rights reserved.
   3  *
   4  * This program is free software; you may redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; version 2 of the License.
   7  *
   8  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   9  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  10  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  11  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  12  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  13  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  14  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  15  * SOFTWARE.
  16  */
  17
  18 #include <linux/module.h>
  19 #include <linux/errno.h>
  20 #include <linux/debugfs.h>
  21 #include "fnic.h"
  22
  23 static struct dentry *fnic_trace_debugfs_root;
  24 static struct dentry *fnic_trace_debugfs_file;
  25 static struct dentry *fnic_trace_enable;
  26
  27 /*
  28  * fnic_trace_ctrl_open - Open the trace_enable file
  29  * @inode: The inode pointer.
  30  * @file: The file pointer to attach the trace enable/disable flag.
  31  *
  32  * Description:
  33  * This routine opens a debugsfs file trace_enable.
  34  *
  35  * Returns:
  36  * This function returns zero if successful.
  37  */
  38 static int fnic_trace_ctrl_open(struct inode *inode, struct file *filp)
  39 {
  40         filp->private_data = inode->i_private;
  41         return 0;
  42 }
  43
  44 /*
  45  * fnic_trace_ctrl_read - Read a trace_enable debugfs file
  46  * @filp: The file pointer to read from.
  47  * @ubuf: The buffer to copy the data to.
  48  * @cnt: The number of bytes to read.
  49  * @ppos: The position in the file to start reading from.
  50  *
  51  * Description:
  52  * This routine reads value of variable fnic_tracing_enabled
  53  * and stores into local @buf. It will start reading file at @ppos and
  54  * copy up to @cnt of data to @ubuf from @buf.
  55  *
  56  * Returns:
  57  * This function returns the amount of data that was read.
  58  */
  59 static ssize_t fnic_trace_ctrl_read(struct file *filp,
  60                                   char __user *ubuf,
  61                                   size_t cnt, loff_t *ppos)
  62 {
  63         char buf[64];
  64         int len;
  65         len = sprintf(buf, "%u\n", fnic_tracing_enabled);
  66
  67         return simple_read_from_buffer(ubuf, cnt, ppos, buf, len);
  68 }
  69
  70 /*
  71  * fnic_trace_ctrl_write - Write to trace_enable debugfs file
  72  * @filp: The file pointer to write from.
  73  * @ubuf: The buffer to copy the data from.
  74  * @cnt: The number of bytes to write.
  75  * @ppos: The position in the file to start writing to.
  76  *
  77  * Description:
  78  * This routine writes data from user buffer @ubuf to buffer @buf and
  79  * sets fnic_tracing_enabled value as per user input.
  80  *
  81  * Returns:
  82  * This function returns the amount of data that was written.
  83  */
  84 static ssize_t fnic_trace_ctrl_write(struct file *filp,
  85                                   const char __user *ubuf,
  86                                   size_t cnt, loff_t *ppos)
  87 {
  88         char buf[64];
  89         unsigned long val;
  90         int ret;
  91
  92         if (cnt >= sizeof(buf))
  93                 return -EINVAL;
  94
  95         if (copy_from_user(&buf, ubuf, cnt))
  96                 return -EFAULT;
  97
  98         buf[cnt] = 0;
  99
 100         ret = kstrtoul(buf, 10, &val);
 101         if (ret < 0)
 102                 return ret;
 103
 104         fnic_tracing_enabled = val;
 105         (*ppos)++;
 106
 107         return cnt;
 108 }
 109
 110 /*
 111  * fnic_trace_debugfs_open - Open the fnic trace log
 112  * @inode: The inode pointer
 113  * @file: The file pointer to attach the log output
 114  *
 115  * Description:
 116  * This routine is the entry point for the debugfs open file operation.
 117  * It allocates the necessary buffer for the log, fills the buffer from
 118  * the in-memory log and then returns a pointer to that log in
 119  * the private_data field in @file.
 120  *
 121  * Returns:
 122  * This function returns zero if successful. On error it will return
 123  * a negative error value.
 124  */
 125 static int fnic_trace_debugfs_open(struct inode *inode,
 126                                   struct file *file)
 127 {
 128         fnic_dbgfs_t *fnic_dbg_prt;
 129         fnic_dbg_prt = kzalloc(sizeof(fnic_dbgfs_t), GFP_KERNEL);
 130         if (!fnic_dbg_prt)
 131                 return -ENOMEM;
 132
 133         fnic_dbg_prt->buffer = vmalloc((3*(trace_max_pages * PAGE_SIZE)));
 134         if (!fnic_dbg_prt->buffer) {
 135                 kfree(fnic_dbg_prt);
 136                 return -ENOMEM;
 137         }
 138         memset((void *)fnic_dbg_prt->buffer, 0,
 139                           (3*(trace_max_pages * PAGE_SIZE)));
 140         fnic_dbg_prt->buffer_len = fnic_get_trace_data(fnic_dbg_prt);
 141         file->private_data = fnic_dbg_prt;
 142         return 0;
 143 }
 144
 145 /*
 146  * fnic_trace_debugfs_lseek - Seek through a debugfs file
 147  * @file: The file pointer to seek through.
 148  * @offset: The offset to seek to or the amount to seek by.
 149  * @howto: Indicates how to seek.
 150  *
 151  * Description:
 152  * This routine is the entry point for the debugfs lseek file operation.
 153  * The @howto parameter indicates whether @offset is the offset to directly
 154  * seek to, or if it is a value to seek forward or reverse by. This function
 155  * figures out what the new offset of the debugfs file will be and assigns
 156  * that value to the f_pos field of @file.
 157  *
 158  * Returns:
 159  * This function returns the new offset if successful and returns a negative
 160  * error if unable to process the seek.
 161  */
 162 static loff_t fnic_trace_debugfs_lseek(struct file *file,
 163                                         loff_t offset,
 164                                         int howto)
 165 {
 166         fnic_dbgfs_t *fnic_dbg_prt = file->private_data;
 167         loff_t pos = -1;
 168
 169         switch (howto) {
 170         case 0:
 171                 pos = offset;
 172                 break;
 173         case 1:
 174                 pos = file->f_pos + offset;
 175                 break;
 176         case 2:
 177                 pos = fnic_dbg_prt->buffer_len + offset;
 178         }
 179         return (pos < 0 || pos > fnic_dbg_prt->buffer_len) ?
 180                           -EINVAL : (file->f_pos = pos);
 181 }
 182
 183 /*
 184  * fnic_trace_debugfs_read - Read a debugfs file
 185  * @file: The file pointer to read from.
 186  * @ubuf: The buffer to copy the data to.
 187  * @nbytes: The number of bytes to read.
 188  * @pos: The position in the file to start reading from.
 189  *
 190  * Description:
 191  * This routine reads data from the buffer indicated in the private_data
 192  * field of @file. It will start reading at @pos and copy up to @nbytes of
 193  * data to @ubuf.
 194  *
 195  * Returns:
 196  * This function returns the amount of data that was read (this could be
 197  * less than @nbytes if the end of the file was reached).
 198  */
 199 static ssize_t fnic_trace_debugfs_read(struct file *file,
 200                                         char __user *ubuf,
 201                                         size_t nbytes,
 202                                         loff_t *pos)
 203 {
 204         fnic_dbgfs_t *fnic_dbg_prt = file->private_data;
 205         int rc = 0;
 206         rc = simple_read_from_buffer(ubuf, nbytes, pos,
 207                                   fnic_dbg_prt->buffer,
 208                                   fnic_dbg_prt->buffer_len);
 209         return rc;
 210 }
 211
 212 /*
 213  * fnic_trace_debugfs_release - Release the buffer used to store
 214  * debugfs file data
 215  * @inode: The inode pointer
 216  * @file: The file pointer that contains the buffer to release
 217  *
 218  * Description:
 219  * This routine frees the buffer that was allocated when the debugfs
 220  * file was opened.
 221  *
 222  * Returns:
 223  * This function returns zero.
 224  */
 225 static int fnic_trace_debugfs_release(struct inode *inode,
 226                                           struct file *file)
 227 {
 228         fnic_dbgfs_t *fnic_dbg_prt = file->private_data;
 229
 230         vfree(fnic_dbg_prt->buffer);
 231         kfree(fnic_dbg_prt);
 232         return 0;
 233 }
 234
 235 static const struct file_operations fnic_trace_ctrl_fops = {
 236         .owner = THIS_MODULE,
 237         .open = fnic_trace_ctrl_open,
 238         .read = fnic_trace_ctrl_read,
 239         .write = fnic_trace_ctrl_write,
 240 };
 241
 242 static const struct file_operations fnic_trace_debugfs_fops = {
 243         .owner = THIS_MODULE,
 244         .open = fnic_trace_debugfs_open,
 245         .llseek = fnic_trace_debugfs_lseek,
 246         .read = fnic_trace_debugfs_read,
 247         .release = fnic_trace_debugfs_release,
 248 };
 249
 250 /*
 251  * fnic_trace_debugfs_init - Initialize debugfs for fnic trace logging
 252  *
 253  * Description:
 254  * When Debugfs is configured this routine sets up the fnic debugfs
 255  * file system. If not already created, this routine will create the
 256  * fnic directory. It will create file trace to log fnic trace buffer
 257  * output into debugfs and it will also create file trace_enable to
 258  * control enable/disable of trace logging into trace buffer.
 259  */
 260 int fnic_trace_debugfs_init(void)
 261 {
 262         int rc = -1;
 263         fnic_trace_debugfs_root = debugfs_create_dir("fnic", NULL);
 264         if (!fnic_trace_debugfs_root) {
 265                 printk(KERN_DEBUG "Cannot create debugfs root\n");
 266                 return rc;
 267         }
 268         fnic_trace_enable = debugfs_create_file("tracing_enable",
 269                                           S_IFREG|S_IRUGO|S_IWUSR,
 270                                           fnic_trace_debugfs_root,
 271                                           NULL, &fnic_trace_ctrl_fops);
 272
 273         if (!fnic_trace_enable) {
 274                 printk(KERN_DEBUG "Cannot create trace_enable file"
 275                                   " under debugfs");
 276                 return rc;
 277         }
 278
 279         fnic_trace_debugfs_file = debugfs_create_file("trace",
 280                                                   S_IFREG|S_IRUGO|S_IWUSR,
 281                                                   fnic_trace_debugfs_root,
 282                                                   NULL,
 283                                                   &fnic_trace_debugfs_fops);
 284
 285         if (!fnic_trace_debugfs_file) {
 286                 printk(KERN_DEBUG "Cannot create trace file under debugfs");
 287                 return rc;
 288         }
 289         rc = 0;
 290         return rc;
 291 }
 292
 293 /*
 294  * fnic_trace_debugfs_terminate - Tear down debugfs infrastructure
 295  *
 296  * Description:
 297  * When Debugfs is configured this routine removes debugfs file system
 298  * elements that are specific to fnic trace logging.
 299  */
 300 void fnic_trace_debugfs_terminate(void)
 301 {
 302         if (fnic_trace_debugfs_file) {
 303                 debugfs_remove(fnic_trace_debugfs_file);
 304                 fnic_trace_debugfs_file = NULL;
 305         }
 306         if (fnic_trace_enable) {
 307                 debugfs_remove(fnic_trace_enable);
 308                 fnic_trace_enable = NULL;
 309         }
 310         if (fnic_trace_debugfs_root) {
 311                 debugfs_remove(fnic_trace_debugfs_root);
 312                 fnic_trace_debugfs_root = NULL;
 313         }
 314 }