linux-kernel - [PATCH 5/5] RISC-V: Move to queued RW locks

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Message-Id: <20220316232600.20419-6-palmer@rivosinc.com>
Date:   Wed, 16 Mar 2022 16:26:00 -0700
From:   Palmer Dabbelt <palmer@...osinc.com>
To:         linux-riscv@...ts.infradead.org, peterz@...radead.org
Cc:     jonas@...thpole.se, stefan.kristiansson@...nalahti.fi,
        shorne@...il.com, mingo@...hat.com, Will Deacon <will@...nel.org>,
        longman@...hat.com, boqun.feng@...il.com,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>, aou@...s.berkeley.edu,
        Arnd Bergmann <arnd@...db.de>, jszhang@...nel.org,
        wangkefeng.wang@...wei.com, openrisc@...ts.librecores.org,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        linux-arch@...r.kernel.org, Palmer Dabbelt <palmer@...osinc.com>
Subject: [PATCH 5/5] RISC-V: Move to queued RW locks

From: Palmer Dabbelt <palmer@...osinc.com>

With the move to fair spinlocks, we might as well move to fair rwlocks.

Signed-off-by: Palmer Dabbelt <palmer@...osinc.com>
---
 arch/riscv/Kconfig                      |  1 +
 arch/riscv/include/asm/Kbuild           |  2 +
 arch/riscv/include/asm/spinlock.h       | 82 +------------------------
 arch/riscv/include/asm/spinlock_types.h |  7 +--
 4 files changed, 5 insertions(+), 87 deletions(-)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 5adcbd9b5e88..feb7030cfb6d 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -38,6 +38,7 @@ config RISCV
 	select ARCH_SUPPORTS_DEBUG_PAGEALLOC if MMU
 	select ARCH_SUPPORTS_HUGETLBFS if MMU
 	select ARCH_USE_MEMTEST
+	select ARCH_USE_QUEUED_RWLOCKS
 	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT if MMU
 	select ARCH_WANT_FRAME_POINTERS
 	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
diff --git a/arch/riscv/include/asm/Kbuild b/arch/riscv/include/asm/Kbuild
index 42b1961af1a6..e8714070cbb9 100644
--- a/arch/riscv/include/asm/Kbuild
+++ b/arch/riscv/include/asm/Kbuild
@@ -4,5 +4,7 @@ generic-y += flat.h
 generic-y += kvm_para.h
 generic-y += ticket-lock.h
 generic-y += ticket-lock-types.h
+generic-y += qrwlock.h
+generic-y += qrwlock_types.h
 generic-y += user.h
 generic-y += vmlinux.lds.h
diff --git a/arch/riscv/include/asm/spinlock.h b/arch/riscv/include/asm/spinlock.h
index 38089cbdea92..97dfb150d18c 100644
--- a/arch/riscv/include/asm/spinlock.h
+++ b/arch/riscv/include/asm/spinlock.h
@@ -11,86 +11,6 @@
 #include <asm/current.h>
 #include <asm/fence.h>
 #include <asm-generic/ticket-lock.h>
-
-static inline void arch_read_lock(arch_rwlock_t *lock)
-{
-	int tmp;
-
-	__asm__ __volatile__(
-		"1:	lr.w	%1, %0\n"
-		"	bltz	%1, 1b\n"
-		"	addi	%1, %1, 1\n"
-		"	sc.w	%1, %1, %0\n"
-		"	bnez	%1, 1b\n"
-		RISCV_ACQUIRE_BARRIER
-		: "+A" (lock->lock), "=&r" (tmp)
-		:: "memory");
-}
-
-static inline void arch_write_lock(arch_rwlock_t *lock)
-{
-	int tmp;
-
-	__asm__ __volatile__(
-		"1:	lr.w	%1, %0\n"
-		"	bnez	%1, 1b\n"
-		"	li	%1, -1\n"
-		"	sc.w	%1, %1, %0\n"
-		"	bnez	%1, 1b\n"
-		RISCV_ACQUIRE_BARRIER
-		: "+A" (lock->lock), "=&r" (tmp)
-		:: "memory");
-}
-
-static inline int arch_read_trylock(arch_rwlock_t *lock)
-{
-	int busy;
-
-	__asm__ __volatile__(
-		"1:	lr.w	%1, %0\n"
-		"	bltz	%1, 1f\n"
-		"	addi	%1, %1, 1\n"
-		"	sc.w	%1, %1, %0\n"
-		"	bnez	%1, 1b\n"
-		RISCV_ACQUIRE_BARRIER
-		"1:\n"
-		: "+A" (lock->lock), "=&r" (busy)
-		:: "memory");
-
-	return !busy;
-}
-
-static inline int arch_write_trylock(arch_rwlock_t *lock)
-{
-	int busy;
-
-	__asm__ __volatile__(
-		"1:	lr.w	%1, %0\n"
-		"	bnez	%1, 1f\n"
-		"	li	%1, -1\n"
-		"	sc.w	%1, %1, %0\n"
-		"	bnez	%1, 1b\n"
-		RISCV_ACQUIRE_BARRIER
-		"1:\n"
-		: "+A" (lock->lock), "=&r" (busy)
-		:: "memory");
-
-	return !busy;
-}
-
-static inline void arch_read_unlock(arch_rwlock_t *lock)
-{
-	__asm__ __volatile__(
-		RISCV_RELEASE_BARRIER
-		"	amoadd.w x0, %1, %0\n"
-		: "+A" (lock->lock)
-		: "r" (-1)
-		: "memory");
-}
-
-static inline void arch_write_unlock(arch_rwlock_t *lock)
-{
-	smp_store_release(&lock->lock, 0);
-}
+#include <asm/qrwlock.h>
 
 #endif /* _ASM_RISCV_SPINLOCK_H */
diff --git a/arch/riscv/include/asm/spinlock_types.h b/arch/riscv/include/asm/spinlock_types.h
index 431ee08e26c4..3779f13706fa 100644
--- a/arch/riscv/include/asm/spinlock_types.h
+++ b/arch/riscv/include/asm/spinlock_types.h
@@ -11,11 +11,6 @@
 #endif
 
 #include <asm-generic/ticket-lock-types.h>
-
-typedef struct {
-	volatile unsigned int lock;
-} arch_rwlock_t;
-
-#define __ARCH_RW_LOCK_UNLOCKED		{ 0 }
+#include <asm/qrwlock_types.h>
 
 #endif /* _ASM_RISCV_SPINLOCK_TYPES_H */
-- 
2.34.1