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>
diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index d9e75ec..883cd44 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -377,6 +377,15 @@
#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, ...) \