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From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
To: linux-snps-arc@lists.infradead.org
Cc: Peter Zijlstra <peterz@infradead.org>,
Will Deacon <will@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
Mark Rutland <mark.rutland@arm.com>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
Vladimir Isaev <Vladimir.Isaev@synopsys.com>,
Vineet Gupta <Vineet.Gupta1@synopsys.com>
Subject: [PATCH 08/11] ARC: xchg: !LLSC: remove UP micro-optimization/hack
Date: Wed, 4 Aug 2021 12:15:51 -0700 [thread overview]
Message-ID: <20210804191554.1252776-9-vgupta@synopsys.com> (raw)
In-Reply-To: <20210804191554.1252776-1-vgupta@synopsys.com>
It gets in the way of cleaning things up and is a maintenance
pain-in-neck !
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
---
arch/arc/include/asm/cmpxchg.h | 12 +-----------
1 file changed, 1 insertion(+), 11 deletions(-)
diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
index d42917e803e1..bac9b564a140 100644
--- a/arch/arc/include/asm/cmpxchg.h
+++ b/arch/arc/include/asm/cmpxchg.h
@@ -113,15 +113,9 @@ static inline unsigned long __xchg(unsigned long val, volatile void *ptr,
* - For !LLSC, cmpxchg() needs to use that lock (see above) and there is lot
* of kernel code which calls xchg()/cmpxchg() on same data (see llist.h)
* Hence xchg() needs to follow same locking rules.
- *
- * Technically the lock is also needed for UP (boils down to irq save/restore)
- * but we can cheat a bit since cmpxchg() atomic_ops_lock() would cause irqs to
- * be disabled thus can't possibly be interrupted/preempted/clobbered by xchg()
- * Other way around, xchg is one instruction anyways, so can't be interrupted
- * as such
*/
-#if !defined(CONFIG_ARC_HAS_LLSC) && defined(CONFIG_SMP)
+#ifndef CONFIG_ARC_HAS_LLSC
#define arch_xchg(ptr, with) \
({ \
@@ -134,10 +128,6 @@ static inline unsigned long __xchg(unsigned long val, volatile void *ptr,
old_val; \
})
-#else
-
-#define arch_xchg(ptr, with) _xchg(ptr, with)
-
#endif
/*
--
2.25.1
next prev parent reply other threads:[~2021-08-04 19:16 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-04 19:15 [PATCH 00/11] ARC atomics update Vineet Gupta
2021-08-04 19:15 ` [PATCH 01/11] ARC: atomics: disintegrate header Vineet Gupta
2021-08-04 19:15 ` [PATCH 02/11] ARC: atomic: !LLSC: remove hack in atomic_set() for for UP Vineet Gupta
2021-08-04 19:15 ` [PATCH 03/11] ARC: atomic: !LLSC: use int data type consistently Vineet Gupta
2021-08-04 19:15 ` [PATCH 04/11] ARC: atomic64: LLSC: elide unused atomic_{and,or,xor,andnot}_return Vineet Gupta
2021-08-04 19:15 ` [PATCH 05/11] ARC: atomics: implement relaxed variants Vineet Gupta
2021-08-04 19:15 ` [PATCH 06/11] ARC: switch to generic bitops Vineet Gupta
2021-08-04 19:15 ` [PATCH 07/11] ARC: bitops: fls/ffs to take int (vs long) per asm-generic defines Vineet Gupta
2021-08-04 19:15 ` Vineet Gupta [this message]
2021-08-04 19:15 ` [PATCH 09/11] ARC: cmpxchg/xchg: rewrite as macros to make type safe Vineet Gupta
2021-08-04 19:15 ` [PATCH 10/11] ARC: cmpxchg/xchg: implement relaxed variants (LLSC config only) Vineet Gupta
2021-08-04 19:15 ` [PATCH 11/11] ARC: atomic_cmpxchg/atomic_xchg: implement relaxed variants Vineet Gupta
2021-08-05 9:02 ` [PATCH 00/11] ARC atomics update Peter Zijlstra
2021-08-05 16:18 ` Vineet Gupta
2021-08-05 17:04 ` Peter Zijlstra
2021-08-05 19:14 ` [RFC] bitops/non-atomic: make @nr unsigned to avoid any DIV Vineet Gupta
2021-08-06 13:42 ` Will Deacon
2021-08-06 19:02 ` Vineet Gupta
2021-08-06 8:41 ` [PATCH 00/11] ARC atomics update Will Deacon
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