parisc: convert /proc/pdc/{lcd,led} to seq_file

Convert code away from ->read_proc/->write_proc interfaces.
Switch to proc_create()/proc_create_data() which make addition of
proc entries reliable wrt NULL ->proc_fops, NULL ->data and so on.

Problem with ->read_proc et al is described here
commit 786d7e1612f0b0adb6046f19b906609e4fe8b1ba
"Fix rmmod/read/write races in /proc entries"

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Reviewed-by: Grant Grundler <grundler@parisc-linux.org>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

1 files changed, 29 insertions, 30 deletions

diff --git a/drivers/parisc/led.c b/drivers/parisc/led.c
index 79caf1ca4a29..188bc8496a26 100644
--- a/drivers/parisc/led.c
+++ b/drivers/parisc/led.c
@@ -38,6 +38,7 @@
 #include <linux/kernel_stat.h>
 #include <linux/reboot.h>
 #include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <linux/ctype.h>
 #include <linux/blkdev.h>
 #include <linux/workqueue.h>
@@ -147,41 +148,34 @@ device_initcall(start_task);
 static void (*led_func_ptr) (unsigned char) __read_mostly;
 
 #ifdef CONFIG_PROC_FS
-static int led_proc_read(char *page, char **start, off_t off, int count, 
-        int *eof, void *data)
+static int led_proc_show(struct seq_file *m, void *v)
 {
-        char *out = page;
-        int len;
-
-        switch ((long)data)
+        switch ((long)m->private)
         {
         case LED_NOLCD:
-                out += sprintf(out, "Heartbeat: %d\n", led_heartbeat);
-                out += sprintf(out, "Disk IO: %d\n", led_diskio);
-                out += sprintf(out, "LAN Rx/Tx: %d\n", led_lanrxtx);
+                seq_printf(m, "Heartbeat: %d\n", led_heartbeat);
+                seq_printf(m, "Disk IO: %d\n", led_diskio);
+                seq_printf(m, "LAN Rx/Tx: %d\n", led_lanrxtx);
                 break;
         case LED_HASLCD:
-                out += sprintf(out, "%s\n", lcd_text);
+                seq_printf(m, "%s\n", lcd_text);
                 break;
         default:
-                *eof = 1;
                 return 0;
         }
+        return 0;
+}
 
-        len = out - page - off;
-        if (len < count) {
-                *eof = 1;
-                if (len <= 0) return 0;
-        } else {
-                len = count;
-        }
-        *start = page + off;
-        return len;
+static int led_proc_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, led_proc_show, PDE(inode)->data);
 }
 
-static int led_proc_write(struct file *file, const char *buf, 
-        unsigned long count, void *data)
+
+static ssize_t led_proc_write(struct file *file, const char *buf,
+        size_t count, loff_t *pos)
 {
+        void *data = PDE(file->f_path.dentry->d_inode)->data;
         char *cur, lbuf[count + 1];
         int d;
 
@@ -234,6 +228,15 @@ parse_error:
         return -EINVAL;
 }
 
+static const struct file_operations led_proc_fops = {
+        .owner          = THIS_MODULE,
+        .open           = led_proc_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+        .write          = led_proc_write,
+};
+
 static int __init led_create_procfs(void)
 {
         struct proc_dir_entry *proc_pdc_root = NULL;
@@ -243,19 +246,15 @@ static int __init led_create_procfs(void)
 
         proc_pdc_root = proc_mkdir("pdc", 0);
         if (!proc_pdc_root) return -1;
-        ent = create_proc_entry("led", S_IFREG|S_IRUGO|S_IWUSR, proc_pdc_root);
+        ent = proc_create_data("led", S_IRUGO|S_IWUSR, proc_pdc_root,
+                                &led_proc_fops, (void *)LED_NOLCD); /* LED */
         if (!ent) return -1;
-        ent->data = (void *)LED_NOLCD; /* LED */
-        ent->read_proc = led_proc_read;
-        ent->write_proc = led_proc_write;
 
         if (led_type == LED_HASLCD)
         {
-                ent = create_proc_entry("lcd", S_IFREG|S_IRUGO|S_IWUSR, proc_pdc_root);
+                ent = proc_create_data("lcd", S_IRUGO|S_IWUSR, proc_pdc_root,
+                                        &led_proc_fops, (void *)LED_HASLCD); /* LCD */
                 if (!ent) return -1;
-                ent->data = (void *)LED_HASLCD; /* LCD */
-                ent->read_proc = led_proc_read;
-                ent->write_proc = led_proc_write;
         }
 
         return 0;