alpha: convert srm code 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>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 33 insertions, 32 deletions

diff --git a/arch/alpha/kernel/srm_env.c b/arch/alpha/kernel/srm_env.c
index d12af472e1c0..dbbf04f9230e 100644
--- a/arch/alpha/kernel/srm_env.c
+++ b/arch/alpha/kernel/srm_env.c
@@ -33,6 +33,7 @@
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <asm/console.h>
 #include <asm/uaccess.h>
 #include <asm/machvec.h>
@@ -79,42 +80,41 @@ static srm_env_t	srm_named_entries[] = {
 static srm_env_t        srm_numbered_entries[256];
 
 
-static int
-srm_env_read(char *page, char **start, off_t off, int count, int *eof,
-                void *data)
+static int srm_env_proc_show(struct seq_file *m, void *v)
 {
-        int             nbytes;
         unsigned long   ret;
         srm_env_t       *entry;
+        char            *page;
 
-        if (off != 0) {
-                *eof = 1;
-                return 0;
-        }
+        entry = (srm_env_t *)m->private;
+        page = (char *)__get_free_page(GFP_USER);
+        if (!page)
+                return -ENOMEM;
 
-        entry   = (srm_env_t *) data;
-        ret     = callback_getenv(entry->id, page, count);
+        ret = callback_getenv(entry->id, page, PAGE_SIZE);
 
         if ((ret >> 61) == 0) {
-                nbytes = (int) ret;
-                *eof = 1;
+                seq_write(m, page, ret);
+                ret = 0;
         } else
-                nbytes = -EFAULT;
+                ret = -EFAULT;
+        free_page((unsigned long)page);
+        return ret;
+}
 
-        return nbytes;
+static int srm_env_proc_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, srm_env_proc_show, PDE(inode)->data);
 }
 
-static int
-srm_env_write(struct file *file, const char __user *buffer, unsigned long count,
-                void *data)
+static ssize_t srm_env_proc_write(struct file *file, const char __user *buffer,
+                                  size_t count, loff_t *pos)
 {
         int res;
-        srm_env_t       *entry;
+        srm_env_t       *entry = PDE(file->f_path.dentry->d_inode)->data;
         char            *buf = (char *) __get_free_page(GFP_USER);
         unsigned long   ret1, ret2;
 
-        entry = (srm_env_t *) data;
-
         if (!buf)
                 return -ENOMEM;
 
@@ -140,6 +140,15 @@ srm_env_write(struct file *file, const char __user *buffer, unsigned long count,
         return res;
 }
 
+static const struct file_operations srm_env_proc_fops = {
+        .owner          = THIS_MODULE,
+        .open           = srm_env_proc_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+        .write          = srm_env_proc_write,
+};
+
 static void
 srm_env_cleanup(void)
 {
@@ -245,15 +254,10 @@ srm_env_init(void)
          */
         entry = srm_named_entries;
         while (entry->name && entry->id) {
-                entry->proc_entry = create_proc_entry(entry->name,
-                                0644, named_dir);
+                entry->proc_entry = proc_create_data(entry->name, 0644, named_dir,
+                                                     &srm_env_proc_fops, entry);
                 if (!entry->proc_entry)
                         goto cleanup;
-
-                entry->proc_entry->data         = (void *) entry;
-                entry->proc_entry->read_proc    = srm_env_read;
-                entry->proc_entry->write_proc   = srm_env_write;
-
                 entry++;
         }
 
@@ -264,15 +268,12 @@ srm_env_init(void)
                 entry = &srm_numbered_entries[var_num];
                 entry->name = number[var_num];
 
-                entry->proc_entry = create_proc_entry(entry->name,
-                                0644, numbered_dir);
+                entry->proc_entry = proc_create_data(entry->name, 0644, numbered_dir,
+                                                     &srm_env_proc_fops, entry);
                 if (!entry->proc_entry)
                         goto cleanup;
 
                 entry->id                       = var_num;
-                entry->proc_entry->data         = (void *) entry;
-                entry->proc_entry->read_proc    = srm_env_read;
-                entry->proc_entry->write_proc   = srm_env_write;
         }
 
         printk(KERN_INFO "%s: version %s loaded successfully\n", NAME,