proc: convert /proc/tty/ldiscs to seq_file interface

Note: THIS_MODULE and header addition aren't technically needed because
      this code is not modular, but let's keep it anyway because people
      can copy this code into modular code.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/proc_tty.c b/fs/proc/proc_tty.c
index 63f45383035d5307029a482419b5ca5f3b1973c4..ac26ccc25f42fc863f1cecf1cdc1ba96ce94ce51 100644 (file)
--- a/fs/proc/proc_tty.c
+++ b/fs/proc/proc_tty.c
@@ -5,7 +5,7 @@
  */
 
 #include <asm/uaccess.h>
-
+#include <linux/module.h>
 #include <linux/init.h>
 #include <linux/errno.h>
 #include <linux/time.h>
@@ -136,39 +136,54 @@ static const struct file_operations proc_tty_drivers_operations = {
        .release        = seq_release,
 };
 
-/*
- * This is the handler for /proc/tty/ldiscs
- */
-static int tty_ldiscs_read_proc(char *page, char **start, off_t off,
-                               int count, int *eof, void *data)
+static void * tty_ldiscs_seq_start(struct seq_file *m, loff_t *pos)
 {
-       int     i;
-       int     len = 0;
-       off_t   begin = 0;
+       return (*pos < NR_LDISCS) ? pos : NULL;
+}
+
+static void * tty_ldiscs_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+       (*pos)++;
+       return (*pos < NR_LDISCS) ? pos : NULL;
+}
+
+static void tty_ldiscs_seq_stop(struct seq_file *m, void *v)
+{
+}
+
+static int tty_ldiscs_seq_show(struct seq_file *m, void *v)
+{
+       int i = *(loff_t *)v;
        struct tty_ldisc *ld;
        
-       for (i=0; i < NR_LDISCS; i++) {
-               ld = tty_ldisc_get(i);
-               if (ld == NULL)
-                       continue;
-               len += sprintf(page+len, "%-10s %2d\n",
-                              ld->name ? ld->name : "???", i);
-               tty_ldisc_put(i);
-               if (len+begin > off+count)
-                       break;
-               if (len+begin < off) {
-                       begin += len;
-                       len = 0;
-               }
-       }
-       if (i >= NR_LDISCS)
-               *eof = 1;
-       if (off >= len+begin)
+       ld = tty_ldisc_get(i);
+       if (ld == NULL)
                return 0;
-       *start = page + (off-begin);
-       return ((count < begin+len-off) ? count : begin+len-off);
+       seq_printf(m, "%-10s %2d\n", ld->name ? ld->name : "???", i);
+       tty_ldisc_put(i);
+       return 0;
+}
+
+static const struct seq_operations tty_ldiscs_seq_ops = {
+       .start  = tty_ldiscs_seq_start,
+       .next   = tty_ldiscs_seq_next,
+       .stop   = tty_ldiscs_seq_stop,
+       .show   = tty_ldiscs_seq_show,
+};
+
+static int proc_tty_ldiscs_open(struct inode *inode, struct file *file)
+{
+       return seq_open(file, &tty_ldiscs_seq_ops);
 }
 
+static const struct file_operations tty_ldiscs_proc_fops = {
+       .owner          = THIS_MODULE,
+       .open           = proc_tty_ldiscs_open,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = seq_release,
+};
+
 /*
  * This function is called by tty_register_driver() to handle
  * registering the driver's /proc handler into /proc/tty/driver/<foo>
@@ -223,8 +238,7 @@ void __init proc_tty_init(void)
         * password lengths and inter-keystroke timings during password
         * entry.
         */
-       proc_tty_driver = proc_mkdir_mode("tty/driver", S_IRUSR | S_IXUSR, NULL);
-
-       create_proc_read_entry("tty/ldiscs", 0, NULL, tty_ldiscs_read_proc, NULL);
+       proc_tty_driver = proc_mkdir_mode("tty/driver", S_IRUSR|S_IXUSR, NULL);
+       proc_create("tty/ldiscs", 0, NULL, &tty_ldiscs_proc_fops);
        proc_create("tty/drivers", 0, NULL, &proc_tty_drivers_operations);
 }