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Message-Id: <8583d54f1687c801c6cda8edddf2cf0344c6e883.1709127473.git.geert+renesas@glider.be>
Date: Wed, 28 Feb 2024 15:00:03 +0100
From: Geert Uytterhoeven <geert+renesas@...der.be>
To: Chris Down <chris@...isdown.name>,
Petr Mladek <pmladek@...e.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Jessica Yu <jeyu@...nel.org>,
Steven Rostedt <rostedt@...dmis.org>,
John Ogness <john.ogness@...utronix.de>,
Sergey Senozhatsky <senozhatsky@...omium.org>,
Jason Baron <jbaron@...mai.com>,
Jim Cromie <jim.cromie@...il.com>,
Ilya Dryomov <idryomov@...il.com>,
Xiubo Li <xiubli@...hat.com>,
Jeff Layton <jlayton@...nel.org>
Cc: linux-kernel@...r.kernel.org,
ceph-devel@...r.kernel.org,
Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH 2/4] dev_printk: Add and use dev_no_printk()
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: ad7d61f159db7397 ("printk: index: Add indexing support to dev_printk")
Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
---
include/linux/dev_printk.h | 25 +++++++++++++------------
1 file changed, 13 insertions(+), 12 deletions(-)
diff --git a/include/linux/dev_printk.h b/include/linux/dev_printk.h
index 6bfe70decc9fb3bc..ae80a303c216be55 100644
--- a/include/linux/dev_printk.h
+++ b/include/linux/dev_printk.h
@@ -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
/*
--
2.34.1
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