1 files changed, 54 insertions, 0 deletions

diff --git a/include/linux/smp_lock.h b/include/linux/smp_lock.h
new file mode 100644
index 000000000000..b63ce7014093
--- /dev/null
+++ b/include/linux/smp_lock.h
@@ -0,0 +1,54 @@
+#ifndef __LINUX_SMPLOCK_H
+#define __LINUX_SMPLOCK_H
+
+#include <linux/config.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+
+#ifdef CONFIG_LOCK_KERNEL
+
+#define kernel_locked()         (current->lock_depth >= 0)
+
+extern int __lockfunc __reacquire_kernel_lock(void);
+extern void __lockfunc __release_kernel_lock(void);
+
+/*
+ * Release/re-acquire global kernel lock for the scheduler
+ */
+#define release_kernel_lock(tsk) do {           \
+        if (unlikely((tsk)->lock_depth >= 0))   \
+                __release_kernel_lock();        \
+} while (0)
+
+/*
+ * Non-SMP kernels will never block on the kernel lock,
+ * so we are better off returning a constant zero from
+ * reacquire_kernel_lock() so that the compiler can see
+ * it at compile-time.
+ */
+#if defined(CONFIG_SMP) && !defined(CONFIG_PREEMPT_BKL)
+# define return_value_on_smp return
+#else
+# define return_value_on_smp
+#endif
+
+static inline int reacquire_kernel_lock(struct task_struct *task)
+{
+        if (unlikely(task->lock_depth >= 0))
+                return_value_on_smp __reacquire_kernel_lock();
+        return 0;
+}
+
+extern void __lockfunc lock_kernel(void)        __acquires(kernel_lock);
+extern void __lockfunc unlock_kernel(void)      __releases(kernel_lock);
+
+#else
+
+#define lock_kernel()                           do { } while(0)
+#define unlock_kernel()                         do { } while(0)
+#define release_kernel_lock(task)               do { } while(0)
+#define reacquire_kernel_lock(task)             0
+#define kernel_locked()                         1
+
+#endif /* CONFIG_LOCK_KERNEL */
+#endif /* __LINUX_SMPLOCK_H */