From: Paul Burton <paul.burton@mips.com>
To: "linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>
Cc: Huacai Chen <chenhc@lemote.com>,
Jiaxun Yang <jiaxun.yang@flygoat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Paul Burton <pburton@wavecomp.com>
Subject: [PATCH v2 23/36] MIPS: bitops: Avoid redundant zero-comparison for non-LLSC
Date: Tue, 1 Oct 2019 21:53:32 +0000 [thread overview]
Message-ID: <20191001215249.4157062-24-paul.burton@mips.com> (raw)
In-Reply-To: <20191001215249.4157062-1-paul.burton@mips.com>
The IRQ-disabling non-LLSC fallbacks for bitops on UP systems already
return a zero or one, so there's no need to perform another comparison
against zero. Move these comparisons into the LLSC paths to avoid the
redundant work.
Signed-off-by: Paul Burton <paul.burton@mips.com>
---
Changes in v2: None
arch/mips/include/asm/bitops.h | 18 ++++++++++++------
1 file changed, 12 insertions(+), 6 deletions(-)
diff --git a/arch/mips/include/asm/bitops.h b/arch/mips/include/asm/bitops.h
index 0f8ff896e86b..7671db2a7b73 100644
--- a/arch/mips/include/asm/bitops.h
+++ b/arch/mips/include/asm/bitops.h
@@ -264,6 +264,8 @@ static inline int test_and_set_bit_lock(unsigned long nr,
: "=&r" (temp), "+m" (*m), "=&r" (res)
: "ir" (BIT(bit))
: __LLSC_CLOBBER);
+
+ res = res != 0;
} else {
loongson_llsc_mb();
do {
@@ -279,12 +281,12 @@ static inline int test_and_set_bit_lock(unsigned long nr,
: __LLSC_CLOBBER);
} while (unlikely(!res));
- res = temp & BIT(bit);
+ res = (temp & BIT(bit)) != 0;
}
smp_llsc_mb();
- return res != 0;
+ return res;
}
/*
@@ -335,6 +337,8 @@ static inline int test_and_clear_bit(unsigned long nr,
: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m), "=&r" (res)
: "ir" (BIT(bit))
: __LLSC_CLOBBER);
+
+ res = res != 0;
} else if ((MIPS_ISA_REV >= 2) && __builtin_constant_p(nr)) {
loongson_llsc_mb();
do {
@@ -363,12 +367,12 @@ static inline int test_and_clear_bit(unsigned long nr,
: __LLSC_CLOBBER);
} while (unlikely(!res));
- res = temp & BIT(bit);
+ res = (temp & BIT(bit)) != 0;
}
smp_llsc_mb();
- return res != 0;
+ return res;
}
/*
@@ -403,6 +407,8 @@ static inline int test_and_change_bit(unsigned long nr,
: "=&r" (temp), "+" GCC_OFF_SMALL_ASM() (*m), "=&r" (res)
: "ir" (BIT(bit))
: __LLSC_CLOBBER);
+
+ res = res != 0;
} else {
loongson_llsc_mb();
do {
@@ -418,12 +424,12 @@ static inline int test_and_change_bit(unsigned long nr,
: __LLSC_CLOBBER);
} while (unlikely(!res));
- res = temp & BIT(bit);
+ res = (temp & BIT(bit)) != 0;
}
smp_llsc_mb();
- return res != 0;
+ return res;
}
#include <asm-generic/bitops/non-atomic.h>
--
2.23.0
next prev parent reply other threads:[~2019-10-01 21:54 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-01 21:53 [PATCH v2 00/36] MIPS: barriers & atomics cleanups Paul Burton
2019-10-01 21:53 ` [PATCH v2 01/36] MIPS: Unify sc beqz definition Paul Burton
2019-10-01 21:53 ` [PATCH v2 02/36] MIPS: Use compact branch for LL/SC loops on MIPSr6+ Paul Burton
2019-10-01 21:53 ` [PATCH v2 03/36] MIPS: barrier: Add __SYNC() infrastructure Paul Burton
2019-10-01 21:53 ` [PATCH v2 04/36] MIPS: barrier: Clean up rmb() & wmb() definitions Paul Burton
2019-10-01 21:53 ` [PATCH v2 05/36] MIPS: barrier: Clean up __smp_mb() definition Paul Burton
2019-10-01 21:53 ` [PATCH v2 06/36] MIPS: barrier: Remove fast_mb() Octeon #ifdef'ery Paul Burton
2019-10-01 21:53 ` [PATCH v2 07/36] MIPS: barrier: Clean up __sync() definition Paul Burton
2019-10-01 21:53 ` [PATCH v2 08/36] MIPS: barrier: Clean up sync_ginv() Paul Burton
2019-10-01 21:53 ` [PATCH v2 09/36] MIPS: atomic: Fix whitespace in ATOMIC_OP macros Paul Burton
2019-10-01 21:53 ` [PATCH v2 10/36] MIPS: atomic: Handle !kernel_uses_llsc first Paul Burton
2019-10-01 21:53 ` [PATCH v2 11/36] MIPS: atomic: Use one macro to generate 32b & 64b functions Paul Burton
2019-10-01 21:53 ` [PATCH v2 12/36] MIPS: atomic: Emit Loongson3 sync workarounds within asm Paul Burton
2019-10-01 21:53 ` [PATCH v2 13/36] MIPS: atomic: Use _atomic barriers in atomic_sub_if_positive() Paul Burton
2019-10-01 21:53 ` [PATCH v2 14/36] MIPS: atomic: Unify 32b & 64b sub_if_positive Paul Burton
2019-10-01 21:53 ` [PATCH v2 15/36] MIPS: atomic: Deduplicate 32b & 64b read, set, xchg, cmpxchg Paul Burton
2019-10-01 21:53 ` [PATCH v2 16/36] MIPS: bitops: Handle !kernel_uses_llsc first Paul Burton
2019-10-01 21:53 ` [PATCH v2 17/36] MIPS: bitops: Only use ins for bit 16 or higher Paul Burton
2019-10-01 21:53 ` [PATCH v2 18/36] MIPS: bitops: Use MIPS_ISA_REV, not #ifdefs Paul Burton
2019-10-01 21:53 ` [PATCH v2 19/36] MIPS: bitops: ins start position is always an immediate Paul Burton
2019-10-01 21:53 ` [PATCH v2 20/36] MIPS: bitops: Implement test_and_set_bit() in terms of _lock variant Paul Burton
2019-10-01 21:53 ` [PATCH v2 21/36] MIPS: bitops: Allow immediates in test_and_{set,clear,change}_bit Paul Burton
2019-10-01 21:53 ` [PATCH v2 22/36] MIPS: bitops: Use the BIT() macro Paul Burton
2019-10-01 21:53 ` Paul Burton [this message]
2019-10-01 21:53 ` [PATCH v2 24/36] MIPS: bitops: Abstract LL/SC loops Paul Burton
2019-10-01 21:53 ` [PATCH v2 25/36] MIPS: bitops: Use BIT_WORD() & BITS_PER_LONG Paul Burton
2019-10-01 21:53 ` [PATCH v2 26/36] MIPS: bitops: Emit Loongson3 sync workarounds within asm Paul Burton
2019-10-01 21:53 ` [PATCH v2 27/36] MIPS: bitops: Use smp_mb__before_atomic in test_* ops Paul Burton
2019-10-01 21:53 ` [PATCH v2 28/36] MIPS: cmpxchg: Emit Loongson3 sync workarounds within asm Paul Burton
2019-10-01 21:53 ` [PATCH v2 29/36] MIPS: cmpxchg: Omit redundant barriers for Loongson3 Paul Burton
2019-10-01 21:53 ` [PATCH v2 30/36] MIPS: futex: Emit Loongson3 sync workarounds within asm Paul Burton
2019-10-01 21:53 ` [PATCH v2 31/36] MIPS: syscall: " Paul Burton
2019-10-01 21:53 ` [PATCH v2 32/36] MIPS: barrier: Remove loongson_llsc_mb() Paul Burton
2019-10-01 21:53 ` [PATCH v2 33/36] MIPS: barrier: Make __smp_mb__before_atomic() a no-op for Loongson3 Paul Burton
2019-10-01 21:53 ` [PATCH v2 34/36] MIPS: genex: Add Loongson3 LL/SC workaround to ejtag_debug_handler Paul Burton
2019-10-01 21:53 ` [PATCH v2 35/36] MIPS: genex: Don't reload address unnecessarily Paul Burton
2019-10-01 21:53 ` [PATCH v2 36/36] MIPS: Check Loongson3 LL/SC errata workaround correctness Paul Burton
2019-10-07 17:51 ` [PATCH v2 00/36] MIPS: barriers & atomics cleanups Paul Burton
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