[PATCH v7 6/6] MCS Lock: add Kconfig entries to allow arch-specific hooks

[Tim Chen <tim.c.chen@linux.intel.com>]

This patch adds Kconfig entries to allow architectures to hook into the
MCS lock/unlock functions in the contended case.

From: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 arch/Kconfig                 | 3 +++
 include/linux/mcs_spinlock.h | 8 ++++++++
 2 files changed, 11 insertions(+)

diff --git a/arch/Kconfig b/arch/Kconfig
index 80bbb8c..8a2a056 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -303,6 +303,9 @@ config HAVE_CMPXCHG_LOCAL
 config HAVE_CMPXCHG_DOUBLE
 	bool
 
+config HAVE_ARCH_MCS_LOCK
+	bool
+
 config ARCH_WANT_IPC_PARSE_VERSION
 	bool
 
diff --git a/include/linux/mcs_spinlock.h b/include/linux/mcs_spinlock.h
index d54bb23..d2c02ad 100644
--- a/include/linux/mcs_spinlock.h
+++ b/include/linux/mcs_spinlock.h
@@ -12,6 +12,14 @@
 #ifndef __LINUX_MCS_SPINLOCK_H
 #define __LINUX_MCS_SPINLOCK_H
 
+/*
+ * An architecture may provide its own lock/unlock functions for the
+ * contended case.
+ */
+#ifdef CONFIG_HAVE_ARCH_MCS_LOCK
+#include <asm/mcs_spinlock.h>
+#endif
+
 struct mcs_spinlock {
 	struct mcs_spinlock *next;
 	int locked; /* 1 if lock acquired */
-- 
1.7.11.7


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