2023-10-20 17:32:01

by Pedro Falcato

Subject: [PATCH] rcu: Remove unused macros from rcupdate.h

ulong2long, USHORT_CMP_GE and USHORT_CMP_LT are redundant and have been
unused for quite a few releases.

Signed-off-by: Pedro Falcato <[email protected]>
---
Just a boring chore patch that cleans up a few unused macros.

I'm *very* interested in knowing how that ulong2long macro came along,
though. What was wrong with '(long) a'?
include/linux/rcupdate.h | 3 ---
1 file changed, 3 deletions(-)

diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 5e5f920ade9..b9b6b828115 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -34,9 +34,6 @@

#define ULONG_CMP_GE(a, b) (ULONG_MAX / 2 >= (a) - (b))
#define ULONG_CMP_LT(a, b) (ULONG_MAX / 2 < (a) - (b))
-#define ulong2long(a) (*(long *)(&(a)))
-#define USHORT_CMP_GE(a, b) (USHRT_MAX / 2 >= (unsigned short)((a) - (b)))
-#define USHORT_CMP_LT(a, b) (USHRT_MAX / 2 < (unsigned short)((a) - (b)))

/* Exported common interfaces */
void call_rcu(struct rcu_head *head, rcu_callback_t func);
--
2.42.0

2023-10-20 19:22:46

by Paul E. McKenney

Subject: Re: [PATCH] rcu: Remove unused macros from rcupdate.h

On Fri, Oct 20, 2023 at 06:30:15PM +0100, Pedro Falcato wrote:
> ulong2long, USHORT_CMP_GE and USHORT_CMP_LT are redundant and have been
> unused for quite a few releases.
>
> Signed-off-by: Pedro Falcato <[email protected]>
> ---
> Just a boring chore patch that cleans up a few unused macros.
>
> I'm *very* interested in knowing how that ulong2long macro came along,
> though. What was wrong with '(long) a'?

Signed integer overflow, if I remember correctly. But the Linux-kernel
build process forced signed integer overflow to be defined.

Queued for v6.8, thank you!

Thanx, Paul

> include/linux/rcupdate.h | 3 ---
> 1 file changed, 3 deletions(-)
>
> diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
> index 5e5f920ade9..b9b6b828115 100644
> --- a/include/linux/rcupdate.h
> +++ b/include/linux/rcupdate.h
> @@ -34,9 +34,6 @@
>
> #define ULONG_CMP_GE(a, b) (ULONG_MAX / 2 >= (a) - (b))
> #define ULONG_CMP_LT(a, b) (ULONG_MAX / 2 < (a) - (b))
> -#define ulong2long(a) (*(long *)(&(a)))
> -#define USHORT_CMP_GE(a, b) (USHRT_MAX / 2 >= (unsigned short)((a) - (b)))
> -#define USHORT_CMP_LT(a, b) (USHRT_MAX / 2 < (unsigned short)((a) - (b)))
>
> /* Exported common interfaces */
> void call_rcu(struct rcu_head *head, rcu_callback_t func);
> --
> 2.42.0
>