[PATCH] uml: locking documentation

Some locking documentation and a cleanup.  uml_exitcode is copied into a local
before sprintf sees it, in case sprintf does anything non-atomic with it.

The rest are comments about why certain globals don't need any kind of
locking.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/arch/um/kernel/exitcode.c b/arch/um/kernel/exitcode.c
index d21ebad666b..8b7f2cdedf9 100644
--- a/arch/um/kernel/exitcode.c
+++ b/arch/um/kernel/exitcode.c
@@ -16,9 +16,13 @@ int uml_exitcode = 0;
 static int read_proc_exitcode(char *page, char **start, off_t off,
 			      int count, int *eof, void *data)
 {
-	int len;
+	int len, val;
 
-	len = sprintf(page, "%d\n", uml_exitcode);
+	/* Save uml_exitcode in a local so that we don't need to guarantee
+	 * that sprintf accesses it atomically.
+	 */
+	val = uml_exitcode;
+	len = sprintf(page, "%d\n", val);
 	len -= off;
 	if(len <= off+count) *eof = 1;
 	*start = page + off;