[PATCH] bitops: Add a comment explaining the double underscore macros

[Dan Carpenter <dan.carpenter@linaro.org>]

Linus Walleij pointed out that a new comer might be confused about the
difference between set_bit() and __set_bit().  Add a comment explaining
the difference.

Link: https://lore.kernel.org/all/CACRpkdZFPG_YLici-BmYfk9HZ36f4WavCN3JNotkk8cPgCODCg@mail.gmail.com/
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
---
 include/linux/bitops.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 46d4bdc634c0..b35a5c3783f6 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -29,6 +29,9 @@ extern unsigned long __sw_hweight64(__u64 w);
 #include <asm-generic/bitops/generic-non-atomic.h>
 
 /*
+ * These double underscore __set_bit(), __clear_bit() macros are non-atomic
+ * versions of set_bit(), clear_bit() and so on.
+ *
  * Many architecture-specific non-atomic bitops contain inline asm code and due
  * to that the compiler can't optimize them to compile-time expressions or
  * constants. In contrary, generic_*() helpers are defined in pure C and
-- 
2.39.2