Merge commit '5bc66170dc486556a1e36fd384463536573f4b82' into x86/urgent

From Borislav Petkov <bp@amd64.org>:

Below is a RAS fix which reverts the addition of a sysfs attribute
which we agreed is not needed, post-factum. And this should go in now
because that sysfs attribute is going to end up in 3.7 otherwise and
thus exposed to userspace; removing it then would be a lot harder.

This is done as a merge rather than a simple patch/cherry-pick since
the baseline for this patch was not in the previous x86/urgent.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 27 insertions, 49 deletions

diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c
index 2340f6978d6..c5ca6ae5a30 100644
--- a/fs/debugfs/file.c
+++ b/fs/debugfs/file.c
@@ -526,73 +526,51 @@ struct array_data {
 	u32 elements;
 };
 
-static int u32_array_open(struct inode *inode, struct file *file)
-{
-	file->private_data = NULL;
-	return nonseekable_open(inode, file);
-}
-
-static size_t format_array(char *buf, size_t bufsize, const char *fmt,
-			   u32 *array, u32 array_size)
+static size_t u32_format_array(char *buf, size_t bufsize,
+			       u32 *array, int array_size)
 {
 	size_t ret = 0;
-	u32 i;
 
-	for (i = 0; i < array_size; i++) {
+	while (--array_size >= 0) {
 		size_t len;
+		char term = array_size ? ' ' : '\n';
 
-		len = snprintf(buf, bufsize, fmt, array[i]);
-		len++;	/* ' ' or '\n' */
+		len = snprintf(buf, bufsize, "%u%c", *array++, term);
 		ret += len;
 
-		if (buf) {
-			buf += len;
-			bufsize -= len;
-			buf[-1] = (i == array_size-1) ? '\n' : ' ';
-		}
+		buf += len;
+		bufsize -= len;
 	}
-
-	ret++;		/* \0 */
-	if (buf)
-		*buf = '\0';
-
 	return ret;
 }
 
-static char *format_array_alloc(const char *fmt, u32 *array,
-						u32 array_size)
+static int u32_array_open(struct inode *inode, struct file *file)
 {
-	size_t len = format_array(NULL, 0, fmt, array, array_size);
-	char *ret;
-
-	ret = kmalloc(len, GFP_KERNEL);
-	if (ret == NULL)
-		return NULL;
+	struct array_data *data = inode->i_private;
+	int size, elements = data->elements;
+	char *buf;
+
+	/*
+	 * Max size:
+	 *  - 10 digits + ' '/'\n' = 11 bytes per number
+	 *  - terminating NUL character
+	 */
+	size = elements*11;
+	buf = kmalloc(size+1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+	buf[size] = 0;
+
+	file->private_data = buf;
+	u32_format_array(buf, size, data->array, data->elements);
 
-	format_array(ret, len, fmt, array, array_size);
-	return ret;
+	return nonseekable_open(inode, file);
 }
 
 static ssize_t u32_array_read(struct file *file, char __user *buf, size_t len,
 			      loff_t *ppos)
 {
-	struct inode *inode = file->f_path.dentry->d_inode;
-	struct array_data *data = inode->i_private;
-	size_t size;
-
-	if (*ppos == 0) {
-		if (file->private_data) {
-			kfree(file->private_data);
-			file->private_data = NULL;
-		}
-
-		file->private_data = format_array_alloc("%u", data->array,
-							      data->elements);
-	}
-
-	size = 0;
-	if (file->private_data)
-		size = strlen(file->private_data);
+	size_t size = strlen(file->private_data);
 
 	return simple_read_from_buffer(buf, len, ppos,
 					file->private_data, size);