Commit 4ccb4579 authored Apr 09, 2009 by Michael Ellerman Committed by Greg Kroah-Hartman Apr 16, 2009

dynamic debug: resurrect old pr_debug() semantics as pr_devel()



pr_debug() used to produce zero code unless DEBUG was #defined.  This is
now no longer the case in practice[1].

There are places where it's useful to have debugging printks, but we don't
want them to generate any code in production kernels.

So add a new macro, pr_devel(), for _devel_opment, to provide the old
semantics, ie.  if the programmer doesn't explicitly enable debugging, no
code is produced.

[1]: You can turn CONFIG_DYNAMIC_DEBUG off, but it's enabled in at least
     one distro kernel, so it's not really a solution.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Greg Banks <gnb@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

parent 13977091

include/linux/kernel.h

+9 −0

Original line number	Diff line number	Diff line
		@@ -377,6 +377,15 @@ static inline char pack_hex_byte(char buf, u8 byte)
		#define pr_cont(fmt, ...) \
		printk(KERN_CONT fmt, ##__VA_ARGS__)

		/* pr_devel() should produce zero code unless DEBUG is defined */
		#ifdef DEBUG
		#define pr_devel(fmt, ...) \
		printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
		#else
		#define pr_devel(fmt, ...) \
		({ if (0) printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); 0; })
		#endif

		/* If you are writing a driver, please use dev_dbg instead */
		#if defined(DEBUG)
		#define pr_debug(fmt, ...) \

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