From: "Paul E. McKenney" <paulmck@kernel.org>
To: 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,
torvalds@linux-foundation.org, Arnd Bergmann <arnd@arndb.de>,
"Paul E. McKenney" <paulmck@kernel.org>,
Vineet Gupta <vgupta@kernel.org>,
Andi Shyti <andi.shyti@linux.intel.com>,
Andrzej Hajda <andrzej.hajda@intel.com>,
Palmer Dabbelt <palmer@rivosinc.com>,
linux-snps-arc@lists.infradead.org
Subject: [PATCH cmpxchg 10/14] ARC: Emulate one-byte cmpxchg
Date: Mon, 8 Apr 2024 10:49:40 -0700 [thread overview]
Message-ID: <20240408174944.907695-10-paulmck@kernel.org> (raw)
In-Reply-To: <7b3646e0-667c-48e2-8f09-e493c43c30cb@paulmck-laptop>
Use the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on arc.
[ paulmck: Drop two-byte support per Arnd Bergmann feedback. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Andrzej Hajda <andrzej.hajda@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Palmer Dabbelt <palmer@rivosinc.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: <linux-snps-arc@lists.infradead.org>
---
arch/arc/Kconfig | 1 +
arch/arc/include/asm/cmpxchg.h | 32 +++++++++++++++++++++++---------
2 files changed, 24 insertions(+), 9 deletions(-)
diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 99d2845f3feb9..5bf6137f0fd47 100644
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -14,6 +14,7 @@ config ARC
select ARCH_HAS_SETUP_DMA_OPS
select ARCH_HAS_SYNC_DMA_FOR_CPU
select ARCH_HAS_SYNC_DMA_FOR_DEVICE
+ select ARCH_NEED_CMPXCHG_1_EMU
select ARCH_SUPPORTS_ATOMIC_RMW if ARC_HAS_LLSC
select ARCH_32BIT_OFF_T
select BUILDTIME_TABLE_SORT
diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
index e138fde067dea..c3833e18389f4 100644
--- a/arch/arc/include/asm/cmpxchg.h
+++ b/arch/arc/include/asm/cmpxchg.h
@@ -46,6 +46,9 @@
__typeof__(*(ptr)) _prev_; \
\
switch(sizeof((_p_))) { \
+ case 1: \
+ _prev_ = cmpxchg_emu_u8((volatile u8 *)_p_, _o_, _n_); \
+ break; \
case 4: \
_prev_ = __cmpxchg(_p_, _o_, _n_); \
break; \
@@ -65,16 +68,27 @@
__typeof__(*(ptr)) _prev_; \
unsigned long __flags; \
\
- BUILD_BUG_ON(sizeof(_p_) != 4); \
+ switch(sizeof((_p_))) { \
+ case 1: \
+ __flags = cmpxchg_emu_u8((volatile u8 *)_p_, _o_, _n_); \
+ _prev_ = (__typeof__(*(ptr)))__flags; \
+ break; \
+ break; \
+ case 4: \
+ /* \
+ * spin lock/unlock provide the needed smp_mb() \
+ * before/after \
+ */ \
+ atomic_ops_lock(__flags); \
+ _prev_ = *_p_; \
+ if (_prev_ == _o_) \
+ *_p_ = _n_; \
+ atomic_ops_unlock(__flags); \
+ break; \
+ default: \
+ BUILD_BUG(); \
+ } \
\
- /* \
- * spin lock/unlock provide the needed smp_mb() before/after \
- */ \
- atomic_ops_lock(__flags); \
- _prev_ = *_p_; \
- if (_prev_ == _o_) \
- *_p_ = _n_; \
- atomic_ops_unlock(__flags); \
_prev_; \
})
--
2.40.1
_______________________________________________
linux-snps-arc mailing list
linux-snps-arc@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-snps-arc
parent reply other threads:[~2024-04-08 17:49 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <7b3646e0-667c-48e2-8f09-e493c43c30cb@paulmck-laptop>]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240408174944.907695-10-paulmck@kernel.org \
--to=paulmck@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=andi.shyti@linux.intel.com \
--cc=andrzej.hajda@intel.com \
--cc=arnd@arndb.de \
--cc=dianders@chromium.org \
--cc=elver@google.com \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-snps-arc@lists.infradead.org \
--cc=palmer@rivosinc.com \
--cc=peterz@infradead.org \
--cc=pmladek@suse.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=vgupta@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).