[RFC PATCH 1/9] kernel.h: add do_empty() macro

[Randy Dunlap]

Add the do_empty() macro to silence gcc warnings about an empty body
following an "if" statement when -Wextra is used.

However, for debug printk calls that are being disabled, use either
no_printk() or pr_debug() [and optionally dynamic printk debugging]
instead.

Signed-off-by: Randy Dunlap <rdunlap at infradead.org>
Cc: Linus Torvalds <torvalds at linux-foundation.org>
Cc: Andrew Morton <akpm at linux-foundation.org>
Cc: Alexander Viro <viro at zeniv.linux.org.uk>
Cc: linux-fsdevel at vger.kernel.org
Cc: Dmitry Torokhov <dmitry.torokhov at gmail.com>
Cc: linux-input at vger.kernel.org
Cc: Jaroslav Kysela <perex at perex.cz>
Cc: Takashi Iwai <tiwai at suse.com>
Cc: alsa-devel at alsa-project.org
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Cc: linux-usb at vger.kernel.org
Cc: "J. Bruce Fields" <bfields at fieldses.org>
Cc: Chuck Lever <chuck.lever at oracle.com>
Cc: linux-nfs at vger.kernel.org
Cc: Johannes Berg <johannes at sipsolutions.net>
Cc: Dan Williams <dan.j.williams at intel.com>
Cc: Vishal Verma <vishal.l.verma at intel.com>
Cc: Dave Jiang <dave.jiang at intel.com>
Cc: linux-nvdimm at lists.01.org
Cc: "Martin K. Petersen" <martin.petersen at oracle.com>
Cc: linux-scsi at vger.kernel.org
Cc: target-devel at vger.kernel.org
Cc: Zzy Wysm <zzy at zzywysm.com>
---
 include/linux/kernel.h |    8 ++++++++
 1 file changed, 8 insertions(+)

--- linux-next-20200327.orig/include/linux/kernel.h
+++ linux-next-20200327/include/linux/kernel.h
@@ -40,6 +40,14 @@
 #define READ			0
 #define WRITE			1
 
+/*
+ * When using -Wextra, an "if" statement followed by an empty block
+ * (containing only a ';'), produces a warning from gcc:
+ * warning: suggest braces around empty body in an ‘if’ statement [-Wempty-body]
+ * Replace the empty body with do_empty() to silence this warning.
+ */
+#define do_empty()		do { } while (0)
+
 /**
  * ARRAY_SIZE - get the number of elements in array @arr
  * @arr: array to be sized