lkml.org 
[lkml]   [2018]   [Apr]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 09/10] locking/qspinlock: Make queued_spin_unlock use smp_store_release
Date
A qspinlock can be unlocked simply by writing zero to the locked byte.
This can be implemented in the generic code, so do that and remove the
arch-specific override for x86 in the !PV case.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
arch/x86/include/asm/qspinlock.h | 17 ++++++-----------
include/asm-generic/qspinlock.h | 2 +-
2 files changed, 7 insertions(+), 12 deletions(-)

diff --git a/arch/x86/include/asm/qspinlock.h b/arch/x86/include/asm/qspinlock.h
index 90b0b0ed8161..cc77cbb01432 100644
--- a/arch/x86/include/asm/qspinlock.h
+++ b/arch/x86/include/asm/qspinlock.h
@@ -7,6 +7,12 @@
#include <asm-generic/qspinlock_types.h>
#include <asm/paravirt.h>

+#ifdef CONFIG_PARAVIRT_SPINLOCKS
+extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
+extern void __pv_init_lock_hash(void);
+extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
+extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock);
+
#define queued_spin_unlock queued_spin_unlock
/**
* queued_spin_unlock - release a queued spinlock
@@ -19,12 +25,6 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock)
smp_store_release(&lock->locked, 0);
}

-#ifdef CONFIG_PARAVIRT_SPINLOCKS
-extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
-extern void __pv_init_lock_hash(void);
-extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
-extern void __raw_callee_save___pv_queued_spin_unlock(struct qspinlock *lock);
-
static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
{
pv_queued_spin_lock_slowpath(lock, val);
@@ -40,11 +40,6 @@ static inline bool vcpu_is_preempted(long cpu)
{
return pv_vcpu_is_preempted(cpu);
}
-#else
-static inline void queued_spin_unlock(struct qspinlock *lock)
-{
- native_queued_spin_unlock(lock);
-}
#endif

#ifdef CONFIG_PARAVIRT
diff --git a/include/asm-generic/qspinlock.h b/include/asm-generic/qspinlock.h
index b37b4ad7eb94..a8ed0a352d75 100644
--- a/include/asm-generic/qspinlock.h
+++ b/include/asm-generic/qspinlock.h
@@ -100,7 +100,7 @@ static __always_inline void queued_spin_unlock(struct qspinlock *lock)
/*
* unlock() needs release semantics:
*/
- (void)atomic_sub_return_release(_Q_LOCKED_VAL, &lock->val);
+ smp_store_release(&lock->locked, 0);
}
#endif

--
2.1.4
\
 
 \ /
  Last update: 2018-04-05 19:00    [W:0.150 / U:8.016 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site