Commit 52aa8536 authored Sep 09, 2015 by Joe Perches Committed by Linus Torvalds Sep 10, 2015

kernel/cred.c: remove unnecessary kdebug atomic reads



Commit e0e81739 ("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>

parent 2307e1a3

kernel/cred.c

+9 −4

Original line number	Diff line number	Diff line
		@@ -21,10 +21,15 @@

		#if 0
		#define kdebug(FMT, ...) \
		printk("[%-5.5s%5u] "FMT"\n", current->comm, current->pid ,##__VA_ARGS__)
		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__)
		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;

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