ARM: convert /proc/cpu/aligment to seq_file

Convert code away from ->read_proc/->write_proc interfaces.  Switch to
proc_create()/proc_create_data() which makes 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"

This patch is part of an effort to remove the old simple procfs PAGE_SIZE
buffer interface.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 26 insertions, 27 deletions

diff --git a/arch/arm/mm/alignment.c b/arch/arm/mm/alignment.c
index edddd66faac6..28b7c2776198 100644
--- a/arch/arm/mm/alignment.c
+++ b/arch/arm/mm/alignment.c
@@ -17,6 +17,7 @@
 #include <linux/errno.h>
 #include <linux/string.h>
 #include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <linux/init.h>
 #include <linux/sched.h>
 #include <linux/uaccess.h>
@@ -94,36 +95,29 @@ static const char *usermode_action[] = {
         "signal+warn"
 };
 
-static int
-proc_alignment_read(char *page, char **start, off_t off, int count, int *eof,
-                    void *data)
+static int alignment_proc_show(struct seq_file *m, void *v)
 {
-        char *p = page;
-        int len;
-
-        p += sprintf(p, "User:\t\t%lu\n", ai_user);
-        p += sprintf(p, "System:\t\t%lu\n", ai_sys);
-        p += sprintf(p, "Skipped:\t%lu\n", ai_skipped);
-        p += sprintf(p, "Half:\t\t%lu\n", ai_half);
-        p += sprintf(p, "Word:\t\t%lu\n", ai_word);
+        seq_printf(m, "User:\t\t%lu\n", ai_user);
+        seq_printf(m, "System:\t\t%lu\n", ai_sys);
+        seq_printf(m, "Skipped:\t%lu\n", ai_skipped);
+        seq_printf(m, "Half:\t\t%lu\n", ai_half);
+        seq_printf(m, "Word:\t\t%lu\n", ai_word);
         if (cpu_architecture() >= CPU_ARCH_ARMv5TE)
-                p += sprintf(p, "DWord:\t\t%lu\n", ai_dword);
-        p += sprintf(p, "Multi:\t\t%lu\n", ai_multi);
-        p += sprintf(p, "User faults:\t%i (%s)\n", ai_usermode,
+                seq_printf(m, "DWord:\t\t%lu\n", ai_dword);
+        seq_printf(m, "Multi:\t\t%lu\n", ai_multi);
+        seq_printf(m, "User faults:\t%i (%s)\n", ai_usermode,
                         usermode_action[ai_usermode]);
 
-        len = (p - page) - off;
-        if (len < 0)
-                len = 0;
-
-        *eof = (len <= count) ? 1 : 0;
-        *start = page + off;
+        return 0;
+}
 
-        return len;
+static int alignment_proc_open(struct inode *inode, struct file *file)
+{
+        return single_open(file, alignment_proc_show, NULL);
 }
 
-static int proc_alignment_write(struct file *file, const char __user *buffer,
-                                unsigned long count, void *data)
+static ssize_t alignment_proc_write(struct file *file, const char __user *buffer,
+                                    size_t count, loff_t *pos)
 {
         char mode;
 
@@ -136,6 +130,13 @@ static int proc_alignment_write(struct file *file, const char __user *buffer,
         return count;
 }
 
+static const struct file_operations alignment_proc_fops = {
+        .open           = alignment_proc_open,
+        .read           = seq_read,
+        .llseek         = seq_lseek,
+        .release        = single_release,
+        .write          = alignment_proc_write,
+};
 #endif /* CONFIG_PROC_FS */
 
 union offset_union {
@@ -901,12 +902,10 @@ static int __init alignment_init(void)
 #ifdef CONFIG_PROC_FS
         struct proc_dir_entry *res;
 
-        res = create_proc_entry("cpu/alignment", S_IWUSR | S_IRUGO, NULL);
+        res = proc_create("cpu/alignment", S_IWUSR | S_IRUGO, NULL,
+                          &alignment_proc_fops);
         if (!res)
                 return -ENOMEM;
-
-        res->read_proc = proc_alignment_read;
-        res->write_proc = proc_alignment_write;
 #endif
 
         /*