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Subject[PATCH v2 5/7] arch/sparc: Enable queued rwlocks for SPARC
Date
Enable queued rwlocks for SPARC. Here are the discussions on this feature
when this was introduced.
https://lwn.net/Articles/572765/
https://lwn.net/Articles/582200/

Cleaned-up the arch_read_xxx and arch_write_xxx definitions in spinlock_64.h.
These routines are replaced by the functions in include/asm-generic/qrwlock.h

Signed-off-by: Babu Moger <babu.moger@oracle.com>
Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com>
Reviewed-by: Jane Chu <jane.chu@oracle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
Reviewed-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
---
arch/sparc/Kconfig | 1 +
arch/sparc/include/asm/qrwlock.h | 7 ++
arch/sparc/include/asm/spinlock_64.h | 124 +------------------------------
arch/sparc/include/asm/spinlock_types.h | 5 +-
4 files changed, 13 insertions(+), 124 deletions(-)
create mode 100644 arch/sparc/include/asm/qrwlock.h

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 0f5813b..9ec1d2f 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -82,6 +82,7 @@ config SPARC64
select HAVE_ARCH_AUDITSYSCALL
select ARCH_SUPPORTS_ATOMIC_RMW
select HAVE_NMI
+ select ARCH_USE_QUEUED_RWLOCKS

config ARCH_DEFCONFIG
string
diff --git a/arch/sparc/include/asm/qrwlock.h b/arch/sparc/include/asm/qrwlock.h
new file mode 100644
index 0000000..d68a4b1
--- /dev/null
+++ b/arch/sparc/include/asm/qrwlock.h
@@ -0,0 +1,7 @@
+#ifndef _ASM_SPARC_QRWLOCK_H
+#define _ASM_SPARC_QRWLOCK_H
+
+#include <asm-generic/qrwlock_types.h>
+#include <asm-generic/qrwlock.h>
+
+#endif /* _ASM_SPARC_QRWLOCK_H */
diff --git a/arch/sparc/include/asm/spinlock_64.h b/arch/sparc/include/asm/spinlock_64.h
index 07c9f2e..8901c2d 100644
--- a/arch/sparc/include/asm/spinlock_64.h
+++ b/arch/sparc/include/asm/spinlock_64.h
@@ -10,6 +10,7 @@

#include <asm/processor.h>
#include <asm/barrier.h>
+#include <asm/qrwlock.h>

/* To get debugging spinlocks which detect and catch
* deadlock situations, set CONFIG_DEBUG_SPINLOCK
@@ -94,132 +95,9 @@ static inline void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long fla
: "memory");
}

-/* Multi-reader locks, these are much saner than the 32-bit Sparc ones... */
-
-static inline void arch_read_lock(arch_rwlock_t *lock)
-{
- unsigned long tmp1, tmp2;
-
- __asm__ __volatile__ (
-"1: ldsw [%2], %0\n"
-" brlz,pn %0, 2f\n"
-"4: add %0, 1, %1\n"
-" cas [%2], %0, %1\n"
-" cmp %0, %1\n"
-" bne,pn %%icc, 1b\n"
-" nop\n"
-" .subsection 2\n"
-"2: ldsw [%2], %0\n"
-" brlz,pt %0, 2b\n"
-" nop\n"
-" ba,a,pt %%xcc, 4b\n"
-" .previous"
- : "=&r" (tmp1), "=&r" (tmp2)
- : "r" (lock)
- : "memory");
-}
-
-static inline int arch_read_trylock(arch_rwlock_t *lock)
-{
- int tmp1, tmp2;
-
- __asm__ __volatile__ (
-"1: ldsw [%2], %0\n"
-" brlz,a,pn %0, 2f\n"
-" mov 0, %0\n"
-" add %0, 1, %1\n"
-" cas [%2], %0, %1\n"
-" cmp %0, %1\n"
-" bne,pn %%icc, 1b\n"
-" mov 1, %0\n"
-"2:"
- : "=&r" (tmp1), "=&r" (tmp2)
- : "r" (lock)
- : "memory");
-
- return tmp1;
-}
-
-static inline void arch_read_unlock(arch_rwlock_t *lock)
-{
- unsigned long tmp1, tmp2;
-
- __asm__ __volatile__(
-"1: lduw [%2], %0\n"
-" sub %0, 1, %1\n"
-" cas [%2], %0, %1\n"
-" cmp %0, %1\n"
-" bne,pn %%xcc, 1b\n"
-" nop"
- : "=&r" (tmp1), "=&r" (tmp2)
- : "r" (lock)
- : "memory");
-}
-
-static inline void arch_write_lock(arch_rwlock_t *lock)
-{
- unsigned long mask, tmp1, tmp2;
-
- mask = 0x80000000UL;
-
- __asm__ __volatile__(
-"1: lduw [%2], %0\n"
-" brnz,pn %0, 2f\n"
-"4: or %0, %3, %1\n"
-" cas [%2], %0, %1\n"
-" cmp %0, %1\n"
-" bne,pn %%icc, 1b\n"
-" nop\n"
-" .subsection 2\n"
-"2: lduw [%2], %0\n"
-" brnz,pt %0, 2b\n"
-" nop\n"
-" ba,a,pt %%xcc, 4b\n"
-" .previous"
- : "=&r" (tmp1), "=&r" (tmp2)
- : "r" (lock), "r" (mask)
- : "memory");
-}
-
-static inline void arch_write_unlock(arch_rwlock_t *lock)
-{
- __asm__ __volatile__(
-" stw %%g0, [%0]"
- : /* no outputs */
- : "r" (lock)
- : "memory");
-}
-
-static inline int arch_write_trylock(arch_rwlock_t *lock)
-{
- unsigned long mask, tmp1, tmp2, result;
-
- mask = 0x80000000UL;
-
- __asm__ __volatile__(
-" mov 0, %2\n"
-"1: lduw [%3], %0\n"
-" brnz,pn %0, 2f\n"
-" or %0, %4, %1\n"
-" cas [%3], %0, %1\n"
-" cmp %0, %1\n"
-" bne,pn %%icc, 1b\n"
-" nop\n"
-" mov 1, %2\n"
-"2:"
- : "=&r" (tmp1), "=&r" (tmp2), "=&r" (result)
- : "r" (lock), "r" (mask)
- : "memory");
-
- return result;
-}
-
#define arch_read_lock_flags(p, f) arch_read_lock(p)
#define arch_write_lock_flags(p, f) arch_write_lock(p)

-#define arch_read_can_lock(rw) (!((rw)->lock & 0x80000000UL))
-#define arch_write_can_lock(rw) (!(rw)->lock)
-
#define arch_spin_relax(lock) cpu_relax()
#define arch_read_relax(lock) cpu_relax()
#define arch_write_relax(lock) cpu_relax()
diff --git a/arch/sparc/include/asm/spinlock_types.h b/arch/sparc/include/asm/spinlock_types.h
index 019c085..64fce21 100644
--- a/arch/sparc/include/asm/spinlock_types.h
+++ b/arch/sparc/include/asm/spinlock_types.h
@@ -7,10 +7,13 @@

#define __ARCH_SPIN_LOCK_UNLOCKED { 0 }

+#ifdef CONFIG_QUEUED_RWLOCKS
+#include <asm-generic/qrwlock_types.h>
+#else
typedef struct {
volatile unsigned int lock;
} arch_rwlock_t;

#define __ARCH_RW_LOCK_UNLOCKED { 0 }
-
+#endif /* CONFIG_QUEUED_RWLOCKS */
#endif
--
1.7.1
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