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kernel/cred.c: remove unnecessary kdebug atomic reads

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Commit e0e817392b ("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>
This commit is contained in:
Joe Perches 2015-09-09 15:36:09 -07:00 committed by Linus Torvalds
parent 2307e1a3c0
commit 52aa8536f8
1 changed files with 9 additions and 4 deletions
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13
kernel/cred.c
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@ -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;