printk: help pr_debug and pr_devel to optimize out arguments
authorAaron Conole <aconole@redhat.com>
Sat, 16 Jan 2016 00:59:12 +0000 (16:59 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sat, 16 Jan 2016 19:17:29 +0000 (11:17 -0800)
commitfe22cd9b7c980b8b948ec85f034a8668c57ec867
tree808061c2a10e26be517783b9b7adf1af1b271288
parent251c72345579b82df59eddfa184af53d6830959c
printk: help pr_debug and pr_devel to optimize out arguments

Currently, pr_debug and pr_devel will not elide function call arguments
appearing in calls to the no_printk for these macros.  This is because
all side effects must be honored before proceeding to the 0-value
assignment in no_printk.

The behavior is contrary to documentation found in the CodingStyle and
the header file where these functions are declared.

This patch corrects that behavior by shunting out the call to no_printk
completely.  The format string is still checked by gcc for correctness,
but no code seems to be emitted in common cases.

[akpm@linux-foundation.org: remove braces, per Joe]
Fixes: 5264f2f75d86 ("include/linux/printk.h: use and neaten no_printk")
Signed-off-by: Aaron Conole <aconole@redhat.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Joe Perches <joe@perches.com>
Cc: Jason Baron <jbaron@akamai.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/printk.h