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authorWaiman Long <Waiman.Long@hp.com>2015-04-24 21:56:31 +0300
committerIngo Molnar <mingo@kernel.org>2015-05-08 13:36:26 +0300
commitd73a33973f16ab6703e75ea00edee857afa3406e (patch)
tree3aee6cd4a8b65ed6fa170a320e23ce39be013cb5 /arch/x86/include/asm/qspinlock.h
parenta33fda35e3a7655fb7df756ed67822afb5ed5e8d (diff)
downloadlinux-d73a33973f16ab6703e75ea00edee857afa3406e.tar.xz
locking/qspinlock, x86: Enable x86-64 to use queued spinlocks
This patch makes the necessary changes at the x86 architecture specific layer to enable the use of queued spinlocks for x86-64. As x86-32 machines are typically not multi-socket. The benefit of queue spinlock may not be apparent. So queued spinlocks are not enabled. Currently, there is some incompatibilities between the para-virtualized spinlock code (which hard-codes the use of ticket spinlock) and the queued spinlocks. Therefore, the use of queued spinlocks is disabled when the para-virtualized spinlock is enabled. The arch/x86/include/asm/qspinlock.h header file includes some x86 specific optimization which will make the queueds spinlock code perform better than the generic implementation. Signed-off-by: Waiman Long <Waiman.Long@hp.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Daniel J Blueman <daniel@numascale.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Douglas Hatch <doug.hatch@hp.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paolo Bonzini <paolo.bonzini@gmail.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Scott J Norton <scott.norton@hp.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/1429901803-29771-3-git-send-email-Waiman.Long@hp.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/qspinlock.h')
-rw-r--r--arch/x86/include/asm/qspinlock.h20
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/x86/include/asm/qspinlock.h b/arch/x86/include/asm/qspinlock.h
new file mode 100644
index 000000000000..e2aee8273664
--- /dev/null
+++ b/arch/x86/include/asm/qspinlock.h
@@ -0,0 +1,20 @@
+#ifndef _ASM_X86_QSPINLOCK_H
+#define _ASM_X86_QSPINLOCK_H
+
+#include <asm-generic/qspinlock_types.h>
+
+#define queued_spin_unlock queued_spin_unlock
+/**
+ * queued_spin_unlock - release a queued spinlock
+ * @lock : Pointer to queued spinlock structure
+ *
+ * A smp_store_release() on the least-significant byte.
+ */
+static inline void queued_spin_unlock(struct qspinlock *lock)
+{
+ smp_store_release((u8 *)lock, 0);
+}
+
+#include <asm-generic/qspinlock.h>
+
+#endif /* _ASM_X86_QSPINLOCK_H */