From 52aa8536f8f41367d5f2938ad67aa87957e70010 Mon Sep 17 00:00:00 2001
From: Joe Perches <joe@perches.com>
Date: Wed, 9 Sep 2015 15:36:09 -0700
Subject: [PATCH] kernel/cred.c: remove unnecessary kdebug atomic reads
Commit e0e817392b9a ("CRED: Add some configurable debugging [try #6]")
added the kdebug mechanism to this file back in 2009.
The kdebug macro calls no_printk which always evaluates arguments.
Most of the kdebug uses have an unnecessary call of
atomic_read(&cred->usage)
Make the kdebug macro do nothing by defining it with
do { if (0) no_printk(...); } while (0)
when not enabled.
$ size kernel/cred.o* (defconfig x86-64)
text data bss dec hex filename
2748 336 8 3092 c14 kernel/cred.o.new
2788 336 8 3132 c3c kernel/cred.o.old
Miscellanea:
o Neaten the #define kdebug macros while there
Signed-off-by: Joe Perches <joe@perches.com>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/cred.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/kernel/cred.c b/kernel/cred.c
index ec1c07667ec1d..71179a09c1d6a 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -20,11 +20,16 @@
#include <linux/cn_proc.h>
#if 0
-#define kdebug(FMT, ...) \
- printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
+#define kdebug(FMT, ...) \
+ printk("[%-5.5s%5u] " FMT "\n", \
+ current->comm, current->pid, ##__VA_ARGS__)
#else
-#define kdebug(FMT, ...) \
- no_printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
+#define kdebug(FMT, ...) \
+do { \
+ if (0) \
+ no_printk("[%-5.5s%5u] " FMT "\n", \
+ current->comm, current->pid, ##__VA_ARGS__); \
+} while (0)
#endif
static struct kmem_cache *cred_jar;
--
GitLab