From: Arnd Bergmann <arnd@arndb.de>
Date: Thu, 01 Feb 2024 14:23:33 +0100

On Thu, Feb 1, 2024, at 13:21, Alexander Lobakin wrote:

quoted

From: Syed Nayyar Waris <redacted>

The two new functions allow reading/writing values of length up to
BITS_PER_LONG bits at arbitrary position in the bitmap.

The code was taken from "bitops: Introduce the for_each_set_clump macro"
by Syed Nayyar Waris with a number of changes and simplifications:
 - instead of using roundup(), which adds an unnecessary dependency
   on <linux/math.h>, we calculate space as BITS_PER_LONG-offset;
 - indentation is reduced by not using else-clauses (suggested by
   checkpatch for bitmap_get_value());
 - bitmap_get_value()/bitmap_set_value() are renamed to bitmap_read()
   and bitmap_write();
 - some redundant computations are omitted.

These functions feel like they should not be inline but are
better off in lib/bitmap.c given their length.

When their arguments are compile-time constants, they got optimized
well. They're also used on hotpath, so making them external could hurt
performance + taking the first sentence into account, making them
external will hurt the performance even more, 'cause they won't be then
as optimized by the compiler as they are now.

As far as I can tell, the header ends up being included
indirectly almost everywhere, so just parsing these functions
likey adds not just dependencies but also compile time.

     Arnd

Thanks,
Olek