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>

diff --git a/arch/alpha/kernel/srm_env.c b/arch/alpha/kernel/srm_env.c
index d12af472e1c0ec4aa380e8bdc73aab15627d7a2c..dbbf04f9230ed0890011e8c63a2db30f8e8d94fe 100644 (file)
--- 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,