Re: [PATCH net-next v3 09/18] include: bitmap: add macro for bitmap initialization

On Wed, 7 Apr 2021 01:38:30 +0200
Andrew Lunn [off-list ref] wrote:

On Wed, Apr 07, 2021 at 12:10:58AM +0200, Marek Behún wrote:

quoted

Use the new variadic-macro.h library to implement macro
INITIALIZE_BITMAP(nbits, ...), which can be used for compile time bitmap
initialization in the form
  static DECLARE_BITMAP(bm, 100) = INITIALIZE_BITMAP(100, 7, 9, 66, 98);

The macro uses the BUILD_BUG_ON_ZERO mechanism to ensure a compile-time
error if an argument is out of range.

Signed-off-by: Marek Behún <kabel@kernel.org>
---
 include/linux/bitmap.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 70a932470b2d..a9e74d3420bf 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h

@@ -8,6 +8,7 @@
 #include <linux/bitops.h>
 #include <linux/string.h>
 #include <linux/kernel.h>
+#include <linux/variadic-macro.h>
 
 /*
  * bitmaps provide bit arrays that consume one or more unsigned

@@ -114,6 +115,29 @@
  * contain all bit positions from 0 to 'bits' - 1.
  */
 
+/**
+ * DOC: initialize bitmap
+ * The INITIALIZE_BITMAP(bits, args...) macro expands to a designated
+ * initializer for bitmap of length 'bits', setting each bit specified
+ * in 'args...'.
+ */  

Doesn't the /** mean this is kernel doc? The rest does not seem to
follow kdoc. Does this compile cleanly with W=1?

       Andrew

Hmm. I just used the same style as was above in the same file, for
/**
 * DOC: declare bitmap
 ...

Anyway W=1 does not complain.

But it does complain about the implementation for INITIALIZE_BITMAP. It
seems that we have to use -Wno-override-init.
This seems to be a new option for gcc. For clang,
scripts/Makefile.extrawarn already uses -Wno-initializer-overrides, but
we have to add -Wno-override-init for gcc.

Marek