From: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
To: "Paul E. McKenney" <paulmck@kernel.org>,
linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: elver@google.com, akpm@linux-foundation.org, tglx@linutronix.de,
peterz@infradead.org, dianders@chromium.org, pmladek@suse.com,
arnd@arndb.de, torvalds@linux-foundation.org,
kernel-team@meta.com, Andi Shyti <andi.shyti@linux.intel.com>,
Palmer Dabbelt <palmer@rivosinc.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
linux-sh@vger.kernel.org
Subject: Re: [PATCH v2 cmpxchg 12/13] sh: Emulate one-byte cmpxchg
Date: Thu, 02 May 2024 06:52:53 +0200 [thread overview]
Message-ID: <1376850f47279e3a3f4f40e3de2784ae3ac30414.camel@physik.fu-berlin.de> (raw)
In-Reply-To: <20240501230130.1111603-12-paulmck@kernel.org>
Hi Paul,
On Wed, 2024-05-01 at 16:01 -0700, Paul E. McKenney wrote:
> Use the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on sh.
>
> [ paulmck: Drop two-byte support per Arnd Bergmann feedback. ]
> [ paulmck: Apply feedback from Naresh Kamboju. ]
> [ Apply Geert Uytterhoeven feedback. ]
>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> Cc: Andi Shyti <andi.shyti@linux.intel.com>
> Cc: Palmer Dabbelt <palmer@rivosinc.com>
> Cc: Masami Hiramatsu <mhiramat@kernel.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: <linux-sh@vger.kernel.org>
> ---
> arch/sh/Kconfig | 1 +
> arch/sh/include/asm/cmpxchg.h | 3 +++
> 2 files changed, 4 insertions(+)
>
> diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
> index 2ad3e29f0ebec..f47e9ccf4efd2 100644
> --- a/arch/sh/Kconfig
> +++ b/arch/sh/Kconfig
> @@ -16,6 +16,7 @@ config SUPERH
> select ARCH_HIBERNATION_POSSIBLE if MMU
> select ARCH_MIGHT_HAVE_PC_PARPORT
> select ARCH_WANT_IPC_PARSE_VERSION
> + select ARCH_NEED_CMPXCHG_1_EMU
> select CPU_NO_EFFICIENT_FFS
> select DMA_DECLARE_COHERENT
> select GENERIC_ATOMIC64
> diff --git a/arch/sh/include/asm/cmpxchg.h b/arch/sh/include/asm/cmpxchg.h
> index 5d617b3ef78f7..1e5dc5ccf7bf5 100644
> --- a/arch/sh/include/asm/cmpxchg.h
> +++ b/arch/sh/include/asm/cmpxchg.h
> @@ -9,6 +9,7 @@
>
> #include <linux/compiler.h>
> #include <linux/types.h>
> +#include <linux/cmpxchg-emu.h>
>
> #if defined(CONFIG_GUSA_RB)
> #include <asm/cmpxchg-grb.h>
> @@ -56,6 +57,8 @@ static inline unsigned long __cmpxchg(volatile void * ptr, unsigned long old,
> unsigned long new, int size)
> {
> switch (size) {
> + case 1:
> + return cmpxchg_emu_u8(ptr, old, new);
> case 4:
> return __cmpxchg_u32(ptr, old, new);
> }
Thanks for the patch. However, I don't quite understand its purpose.
There is already a case for 8-byte cmpxchg in the switch statement below:
case 1: \
__xchg__res = xchg_u8(__xchg_ptr, x); \
break;
Does cmpxchg_emu_u8() have any advantages over the native xchg_u8()?
Thanks,
Adrian
--
.''`. John Paul Adrian Glaubitz
: :' : Debian Developer
`. `' Physicist
`- GPG: 62FF 8A75 84E0 2956 9546 0006 7426 3B37 F5B5 F913
next prev parent reply other threads:[~2024-05-02 4:53 UTC|newest]
Thread overview: 125+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-01 21:39 [PATCH RFC cmpxchg 0/8] Provide emulation for one- and two-byte cmpxchg() Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 1/8] lib: Add one-byte and two-byte cmpxchg() emulation functions Paul E. McKenney
2024-04-02 13:07 ` Marco Elver
2024-04-02 17:15 ` Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 2/8] sparc: Emulate one-byte and two-byte cmpxchg Paul E. McKenney
2024-04-01 22:38 ` Al Viro
2024-04-01 23:58 ` Paul E. McKenney
2024-04-02 0:07 ` Al Viro
2024-04-02 3:37 ` Al Viro
2024-04-02 4:11 ` Al Viro
2024-04-02 4:18 ` Paul E. McKenney
2024-04-02 4:28 ` [PATCH 1/8] sparc32: make __cmpxchg_u32() return u32 Al Viro
2024-04-02 4:28 ` [PATCH 2/8] sparc32: make the first argument of __cmpxchg_u64() volatile u64 * Al Viro
2024-04-02 4:28 ` [PATCH 3/8] sparc32: unify __cmpxchg_u{32,64} Al Viro
2024-04-02 7:28 ` Arnd Bergmann
2024-04-02 20:02 ` Paul E. McKenney
2024-04-02 4:28 ` [PATCH 4/8] sparc32: add __cmpxchg_u{8,16}() and teach __cmpxchg() to handle those sizes Al Viro
2024-04-02 4:28 ` [PATCH 5/8] parisc: __cmpxchg_u32(): lift conversion into the callers Al Viro
2024-04-02 4:28 ` [PATCH 6/8] parisc: unify implementations of __cmpxchg_u{8,32,64} Al Viro
2024-04-02 4:28 ` [PATCH 7/8] parisc: add missing export of __cmpxchg_u8() Al Viro
2024-04-02 4:28 ` [PATCH 8/8] parisc: add u16 support to cmpxchg() Al Viro
2024-04-02 20:03 ` [PATCH 1/8] sparc32: make __cmpxchg_u32() return u32 Paul E. McKenney
2024-04-03 22:20 ` Al Viro
2024-04-04 3:09 ` Paul E. McKenney
2024-04-02 4:17 ` [PATCH RFC cmpxchg 2/8] sparc: Emulate one-byte and two-byte cmpxchg Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 3/8] ARC: " Paul E. McKenney
2024-04-02 8:14 ` Arnd Bergmann
2024-04-02 17:06 ` Paul E. McKenney
2024-04-02 20:52 ` Paul E. McKenney
2024-04-04 11:57 ` Arnd Bergmann
2024-04-04 14:44 ` Paul E. McKenney
2024-04-04 15:06 ` Arnd Bergmann
2024-04-01 21:39 ` [PATCH RFC cmpxchg 4/8] csky: " Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 5/8] sh: " Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 6/8] xtensa: " Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 7/8] parisc: Emulate " Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 8/8] riscv: Emulate one-byte and " Paul E. McKenney
2024-04-04 14:15 ` Palmer Dabbelt
2024-04-04 14:50 ` Paul E. McKenney
2024-05-11 6:50 ` Guo Ren
2024-05-11 14:54 ` Paul E. McKenney
2024-05-11 20:44 ` Leonardo Bras
2024-04-08 17:47 ` [PATCH RFC cmpxchg 0/8] Provide emulation for one- and two-byte cmpxchg() Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 01/14] sparc32: make __cmpxchg_u32() return u32 Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 02/14] sparc32: make the first argument of __cmpxchg_u64() volatile u64 * Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 03/14] sparc32: unify __cmpxchg_u{32,64} Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 04/14] sparc32: add __cmpxchg_u{8,16}() and teach __cmpxchg() to handle those sizes Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 05/14] parisc: __cmpxchg_u32(): lift conversion into the callers Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 06/14] parisc: unify implementations of __cmpxchg_u{8,32,64} Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 07/14] parisc: add missing export of __cmpxchg_u8() Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 08/14] parisc: add u16 support to cmpxchg() Paul E. McKenney
2024-04-08 20:10 ` Linus Torvalds
2024-04-08 20:53 ` Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 09/14] lib: Add one-byte emulation function Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 10/14] ARC: Emulate one-byte cmpxchg Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 11/14] csky: " Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 12/14] sh: " Paul E. McKenney
2024-04-18 8:04 ` Geert Uytterhoeven
2024-04-08 17:49 ` [PATCH cmpxchg 13/14] xtensa: " Paul E. McKenney
2024-04-18 8:06 ` Geert Uytterhoeven
2024-04-18 23:21 ` Paul E. McKenney
2024-04-19 5:07 ` Yujie Liu
2024-04-19 8:02 ` Geert Uytterhoeven
2024-04-20 14:03 ` Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 14/14] riscv: " Paul E. McKenney
2024-04-09 17:35 ` Andrea Parri
2024-04-09 18:08 ` Paul E. McKenney
2024-05-01 22:58 ` [PATCH v2 cmpxchg 0/8] Provide emulation for one--byte cmpxchg() Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 01/13] sparc32: make __cmpxchg_u32() return u32 Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 02/13] sparc32: make the first argument of __cmpxchg_u64() volatile u64 * Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 03/13] sparc32: unify __cmpxchg_u{32,64} Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 04/13] sparc32: add __cmpxchg_u{8,16}() and teach __cmpxchg() to handle those sizes Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 05/13] parisc: __cmpxchg_u32(): lift conversion into the callers Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 06/13] parisc: unify implementations of __cmpxchg_u{8,32,64} Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 07/13] parisc: add missing export of __cmpxchg_u8() Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 08/13] parisc: add u16 support to cmpxchg() Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 09/13] lib: Add one-byte emulation function Paul E. McKenney
2024-05-13 14:44 ` Boqun Feng
2024-05-13 15:41 ` Paul E. McKenney
2024-05-13 15:57 ` Boqun Feng
2024-05-13 21:19 ` Boqun Feng
2024-05-14 14:22 ` Paul E. McKenney
2024-05-14 14:53 ` Boqun Feng
2024-05-14 15:02 ` Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 10/13] ARC: Emulate one-byte cmpxchg Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 11/13] csky: " Paul E. McKenney
2024-05-11 6:42 ` Guo Ren
2024-05-11 14:49 ` Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 12/13] sh: " Paul E. McKenney
2024-05-02 4:52 ` John Paul Adrian Glaubitz [this message]
2024-05-02 5:06 ` Paul E. McKenney
2024-05-02 5:11 ` John Paul Adrian Glaubitz
2024-05-02 13:33 ` Paul E. McKenney
2024-05-02 20:53 ` Al Viro
2024-05-02 21:01 ` alpha cmpxchg.h (was Re: [PATCH v2 cmpxchg 12/13] sh: Emulate one-byte cmpxchg) Al Viro
2024-05-02 22:16 ` Linus Torvalds
2024-05-02 21:18 ` [PATCH v2 cmpxchg 12/13] sh: Emulate one-byte cmpxchg Paul E. McKenney
2024-05-02 22:07 ` Al Viro
2024-05-02 23:12 ` Paul E. McKenney
2024-05-02 23:24 ` Al Viro
2024-05-02 23:45 ` Paul E. McKenney
2024-05-02 23:32 ` Linus Torvalds
2024-05-03 0:16 ` Paul E. McKenney
2024-05-02 21:50 ` Arnd Bergmann
2024-05-02 5:42 ` D. Jeff Dionne
2024-05-02 11:30 ` Arnd Bergmann
2024-05-01 23:01 ` [PATCH v2 cmpxchg 13/13] xtensa: " Paul E. McKenney
2024-05-02 20:01 ` [PATCH v2 cmpxchg 0/8] Provide emulation for one--byte cmpxchg() Al Viro
2024-05-02 21:20 ` Paul E. McKenney
2024-06-04 17:02 ` [PATCH v3 cmpxchg 0/4] " Paul E. McKenney
2024-06-04 17:04 ` [PATCH v3 cmpxchg 1/4] ARC: Emulate one-byte cmpxchg Paul E. McKenney
2024-06-04 17:04 ` [PATCH v3 cmpxchg 2/4] sh: " Paul E. McKenney
2024-06-04 17:09 ` John Paul Adrian Glaubitz
2024-06-04 17:50 ` Paul E. McKenney
2024-06-04 17:56 ` John Paul Adrian Glaubitz
2024-06-04 21:14 ` Paul E. McKenney
2024-06-17 16:50 ` Paul E. McKenney
2024-06-17 20:30 ` John Paul Adrian Glaubitz
2024-06-17 21:59 ` Paul E. McKenney
2024-06-04 17:04 ` [PATCH v3 cmpxchg 3/4] xtensa: " Paul E. McKenney
2024-06-04 17:04 ` [PATCH v3 cmpxchg 4/4] ARM: " Paul E. McKenney
2024-06-04 20:52 ` Linus Walleij
2024-06-04 21:14 ` Paul E. McKenney
2024-06-05 8:38 ` Linus Walleij
2024-06-05 18:05 ` Paul E. McKenney
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