LXR linux/fs/proc/devices.c

   1// SPDX-License-Identifier: GPL-2.0
   2#include <linux/fs.h>
   3#include <linux/init.h>
   4#include <linux/proc_fs.h>
   5#include <linux/seq_file.h>
   6
   7static int devinfo_show(struct seq_file *f, void *v)
   8{
   9        int i = *(loff_t *) v;
  10
  11        if (i < CHRDEV_MAJOR_MAX) {
  12                if (i == 0)
  13                        seq_puts(f, "Character devices:\n");
  14                chrdev_show(f, i);
  15        }
  16#ifdef CONFIG_BLOCK
  17        else {
  18                i -= CHRDEV_MAJOR_MAX;
  19                if (i == 0)
  20                        seq_puts(f, "\nBlock devices:\n");
  21                blkdev_show(f, i);
  22        }
  23#endif
  24        return 0;
  25}
  26
  27static void *devinfo_start(struct seq_file *f, loff_t *pos)
  28{
  29        if (*pos < (BLKDEV_MAJOR_MAX + CHRDEV_MAJOR_MAX))
  30                return pos;
  31        return NULL;
  32}
  33
  34static void *devinfo_next(struct seq_file *f, void *v, loff_t *pos)
  35{
  36        (*pos)++;
  37        if (*pos >= (BLKDEV_MAJOR_MAX + CHRDEV_MAJOR_MAX))
  38                return NULL;
  39        return pos;
  40}
  41
  42static void devinfo_stop(struct seq_file *f, void *v)
  43{
  44        /* Nothing to do */
  45}
  46
  47static const struct seq_operations devinfo_ops = {
  48        .start = devinfo_start,
  49        .next  = devinfo_next,
  50        .stop  = devinfo_stop,
  51        .show  = devinfo_show
  52};
  53
  54static int __init proc_devices_init(void)
  55{
  56        proc_create_seq("devices", 0, NULL, &devinfo_ops);
  57        return 0;
  58}
  59fs_initcall(proc_devices_init);
  60