When DEBUG is not defined, pr_debug and dev_dbg and some
other local debugging functions are specified as:
"inline __attribute__((format (printf, x, y)))"
This is done to validate printk arguments when not debugging.
Converting these functions to macros or statement expressions
"do { if (0) printk(fmt, ##arg); } while (0)"
or
"({ if (0) printk(fmt, ##arg); 0; })
makes at least gcc 4.2.2 produce smaller objects.
This has the additional benefit of allowing the optimizer to
avoid calling functions like print_mac that might have been
arguments to the printk.
defconfig x86 current:
$ size vmlinux
text data bss dec hex filename
4716770 474560 618496 5809826 58a6a2 vmlinux
all converted: (More patches follow)
$ size vmlinux
text data bss dec hex filename
4716642 474560 618496 5809698 58a622 vmlinux
Even kernel/sched.o, which doesn't even use these
functions, becomes smaller.
It appears that merely having an indirect include
of <linux/device.h> can cause bigger objects.
$ size sched.inline.o sched.if0.o
text data bss dec hex filename
31385 2854 328 34567 8707 sched.inline.o
31366 2854 328 34548 86f4 sched.if0.o
The current preprocessed only kernel/sched.i file contains:
# 612 "include/linux/device.h"
static inline __attribute__((always_inline)) int __attribute__ ((format (printf, 2, 3)))
dev_dbg(struct device *dev, const char *fmt, ...)
{
return 0;
}
# 628 "include/linux/device.h"
static inline __attribute__((always_inline)) int __attribute__ ((format (printf, 2, 3)))
dev_vdbg(struct device *dev, const char *fmt, ...)
{
return 0;
}
Removing these unused inlines from sched.i shrinks sched.o
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
1429db83e2