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dev_printk: Add and use dev_no_printk()

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When printk-indexing is enabled, each dev_printk() invocation emits a
pi_entry structure.  This is even true when the dev_printk() is
protected by an always-false check, as is typically the case for debug
messages: while the actual code to print the message is optimized out by
the compiler, the pi_entry structure is still emitted.

Avoid emitting pi_entry structures for unavailable dev_printk() kernel
messages by:
  1. Introducing a dev_no_printk() helper, mimicked after the existing
     no_printk() helper, which calls _dev_printk() instead of
     dev_printk(),
  2. Replacing all "if (0) dev_printk(...)" constructs by calls to the
     new helper.

This reduces the size of an arm64 defconfig kernel with
CONFIG_PRINTK_INDEX=y by 957 KiB.

Fixes: ad7d61f159 ("printk: index: Add indexing support to dev_printk")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
Reviewed-by: Chris Down <chris@chrisdown.name>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/8583d54f1687c801c6cda8edddf2cf0344c6e883.1709127473.git.geert+renesas@glider.be
Signed-off-by: Petr Mladek <pmladek@suse.com>
This commit is contained in:
Geert Uytterhoeven 2024-02-28 15:00:03 +01:00 committed by Petr Mladek
parent 8522f6b760
commit c26ec79904
1 changed files with 13 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
include/linux/dev_printk.h
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@ -129,6 +129,16 @@ void _dev_info(const struct device *dev, const char *fmt, ...)
_dev_printk(level, dev, fmt, ##__VA_ARGS__); \
})
/*
* Dummy dev_printk for disabled debugging statements to use whilst maintaining
* gcc's format checking.
*/
#define dev_no_printk(level, dev, fmt, ...) \
({ \
if (0) \
_dev_printk(level, dev, fmt, ##__VA_ARGS__); \
})
/*
* #defines for all the dev_<level> macros to prefix with whatever
* possible use of #define dev_fmt(fmt) ...
@ -158,10 +168,7 @@ void _dev_info(const struct device *dev, const char *fmt, ...)
dev_printk(KERN_DEBUG, dev, dev_fmt(fmt), ##__VA_ARGS__)
#else
#define dev_dbg(dev, fmt, ...) \
({ \
if (0) \
dev_printk(KERN_DEBUG, dev, dev_fmt(fmt), ##__VA_ARGS__); \
})
dev_no_printk(KERN_DEBUG, dev, dev_fmt(fmt), ##__VA_ARGS__)
#endif
#ifdef CONFIG_PRINTK
@ -247,20 +254,14 @@ do { \
} while (0)
#else
#define dev_dbg_ratelimited(dev, fmt, ...) \
do { \
if (0) \
dev_printk(KERN_DEBUG, dev, dev_fmt(fmt), ##__VA_ARGS__); \
} while (0)
dev_no_printk(KERN_DEBUG, dev, dev_fmt(fmt), ##__VA_ARGS__)
#endif
#ifdef VERBOSE_DEBUG
#define dev_vdbg dev_dbg
#else
#define dev_vdbg(dev, fmt, ...) \
({ \
if (0) \
dev_printk(KERN_DEBUG, dev, dev_fmt(fmt), ##__VA_ARGS__); \
})
dev_no_printk(KERN_DEBUG, dev, dev_fmt(fmt), ##__VA_ARGS__)
#endif
/*