This patch makes the necessary changes at the x86 architecture specific
layer to enable the presence of the CONFIG_QUEUE_SPINLOCK kernel option
which can be used to replace the ticket spinlock by the queue spinlock.
The turning on of ARCH_QUEUE_SPINLOCK config option does not mean
that the ticket spinlock will be replaced. It only means that the
architecture supports the replacement. Actual replacement will only
happen if the QUEUE_SPINLOCK config option is also set.
Signed-off-by: Waiman Long <Waiman.Long@xxxxxx>
---
arch/x86/Kconfig | 3 +++
arch/x86/include/asm/spinlock.h | 2 ++
arch/x86/include/asm/spinlock_types.h | 4 ++++
arch/x86/kernel/paravirt-spinlocks.c | 10 ++++++++++
4 files changed, 19 insertions(+), 0 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b32ebf9..8531e47 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2344,6 +2344,9 @@ config X86_DMA_REMAP
bool
depends on STA2X11
+config ARCH_QUEUE_SPINLOCK
+ def_bool y
+
source "net/Kconfig"
source "drivers/Kconfig"
diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
index 33692ea..0ea805d 100644
--- a/arch/x86/include/asm/spinlock.h
+++ b/arch/x86/include/asm/spinlock.h
@@ -34,6 +34,7 @@
# define UNLOCK_LOCK_PREFIX
#endif
+#ifndef CONFIG_QUEUE_SPINLOCK
/*
* Ticket locks are conceptually two parts, one indicating the current head of
* the queue, and the other indicating the current tail. The lock is acquired
@@ -130,6 +131,7 @@ static __always_inline void arch_spin_lock_flags(arch_spinlock_t *lock,
}
#endif /* CONFIG_PARAVIRT_SPINLOCKS */
+#endif /* !CONFIG_QUEUE_SPINLOCK */
static inline void arch_spin_unlock_wait(arch_spinlock_t *lock)
{
diff --git a/arch/x86/include/asm/spinlock_types.h b/arch/x86/include/asm/spinlock_types.h
index ad0ad07..8a7721e 100644
--- a/arch/x86/include/asm/spinlock_types.h
+++ b/arch/x86/include/asm/spinlock_types.h
@@ -7,6 +7,9 @@
#include <linux/types.h>
+#ifdef CONFIG_QUEUE_SPINLOCK
+# include <asm-generic/qspinlock.h>
+#else
#if (CONFIG_NR_CPUS < 256)
typedef u8 __ticket_t;
typedef u16 __ticketpair_t;
@@ -27,6 +30,7 @@ typedef struct arch_spinlock {
} arch_spinlock_t;
#define __ARCH_SPIN_LOCK_UNLOCKED { { 0 } }
+#endif
#include <asm/rwlock.h>
diff --git a/arch/x86/kernel/paravirt-spinlocks.c b/arch/x86/kernel/paravirt-spinlocks.c
index 676b8c7..75569cb 100644
--- a/arch/x86/kernel/paravirt-spinlocks.c
+++ b/arch/x86/kernel/paravirt-spinlocks.c
@@ -15,6 +15,15 @@ default_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
struct pv_lock_ops pv_lock_ops = {
#ifdef CONFIG_SMP
+# ifdef CONFIG_QUEUE_SPINLOCK
+ .spin_is_locked = queue_spin_is_locked,
+ .spin_is_contended = queue_spin_is_contended,
+
+ .spin_lock = queue_spin_lock,
+ .spin_lock_flags = default_spin_lock_flags,
+ .spin_trylock = queue_spin_trylock,
+ .spin_unlock = queue_spin_unlock,
+# else
.spin_is_locked = __ticket_spin_is_locked,
.spin_is_contended = __ticket_spin_is_contended,
@@ -22,6 +31,7 @@ struct pv_lock_ops pv_lock_ops = {
.spin_lock_flags = default_spin_lock_flags,
.spin_trylock = __ticket_spin_trylock,
.spin_unlock = __ticket_spin_unlock,
+# endif
#endif
};
EXPORT_SYMBOL(pv_lock_ops);
--
1.7.1
--
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