Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 10/36] driver core: Convert debug functions declared inline __attribute__((format (printf,x,y) to statement expression macros | Date | Sun, 20 Apr 2008 03:45:40 -0700 |
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From: Joe Perches <joe@perches.com>
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> --- include/linux/device.h | 15 +++++---------- include/linux/kernel.h | 6 ++---- 2 files changed, 7 insertions(+), 14 deletions(-)
diff --git a/include/linux/device.h b/include/linux/device.h index 2258d89..d576611 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -608,21 +608,16 @@ extern const char *dev_driver_string(struct device *dev); #define dev_dbg(dev, format, arg...) \ dev_printk(KERN_DEBUG , dev , format , ## arg) #else -static inline int __attribute__ ((format (printf, 2, 3))) -dev_dbg(struct device *dev, const char *fmt, ...) -{ - return 0; -} +#define dev_dbg(dev, format, arg...) \ + ({ if (0) dev_printk(KERN_DEBUG, dev, format, ##arg); 0; }) #endif #ifdef VERBOSE_DEBUG #define dev_vdbg dev_dbg #else -static inline int __attribute__ ((format (printf, 2, 3))) -dev_vdbg(struct device *dev, const char *fmt, ...) -{ - return 0; -} + +#define dev_vdbg(dev, format, arg...) \ + ({ if (0) dev_printk(KERN_DEBUG, dev, format, ##arg); 0; }) #endif /* Create alias, so I can be autoloaded. */ diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 2df44e7..cd6d02c 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -293,10 +293,8 @@ extern void print_hex_dump_bytes(const char *prefix_str, int prefix_type, #define pr_debug(fmt, arg...) \ printk(KERN_DEBUG fmt, ##arg) #else -static inline int __attribute__ ((format (printf, 1, 2))) pr_debug(const char * fmt, ...) -{ - return 0; -} +#define pr_debug(fmt, arg...) \ + ({ if (0) printk(KERN_DEBUG fmt, ##arg); 0; }) #endif /* -- 1.5.4.5
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