[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@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Cc: linux-input@xxxxxxxxxxxxxxx
Cc: Jaroslav Kysela <perex@xxxxxxxx>
Cc: Takashi Iwai <tiwai@xxxxxxxx>
Cc: alsa-devel@xxxxxxxxxxxxxxxx
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: linux-usb@xxxxxxxxxxxxxxx
Cc: "J. Bruce Fields" <bfields@xxxxxxxxxxxx>
Cc: Chuck Lever <chuck.lever@xxxxxxxxxx>
Cc: linux-nfs@xxxxxxxxxxxxxxx
Cc: Johannes Berg <johannes@xxxxxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Vishal Verma <vishal.l.verma@xxxxxxxxx>
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Cc: linux-nvdimm@xxxxxxxxxxxx
Cc: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>
Cc: linux-scsi@xxxxxxxxxxxxxxx
Cc: target-devel@xxxxxxxxxxxxxxx
Cc: Zzy Wysm <zzy@xxxxxxxxxxx>
---
 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 âifâ 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