[RFC PATCH 1/2] arch/generic/sh/x86/powerpc/ia64: add __mutex_fastpath_lock_retval_arg

[Maarten Lankhorst <maarten.lankhorst@canonical.com>]

I was hoping to convert the 'mutexes' in ttm to proper mutexes, so I extended the
core mutex code slightly to add support for reservations. This requires however
passing an argument to __mutex_fastpath_lock_retval, so I added this for all archs
based on their existing __mutex_fastpath_lock_retval implementation.

I'm guessing this has to be split up, but I figured most of the flames would be
about patch 2 anyhow..

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@canonical.com>

---
diff --git a/arch/ia64/include/asm/mutex.h b/arch/ia64/include/asm/mutex.h
index bed73a6..2510058 100644
--- a/arch/ia64/include/asm/mutex.h
+++ b/arch/ia64/include/asm/mutex.h
@@ -44,6 +44,26 @@ __mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
 }
 
 /**
+ *  __mutex_fastpath_lock_retval_arg - try to take the lock by moving the count
+ *                                     from 1 to a 0 value
+ *  @count: pointer of type atomic_t
+ *  @arg: argument to pass along if fastpath fails.
+ *  @fail_fn: function to call if the original value was not 1
+ *
+ * Change the count from 1 to a value lower than 1, and call <fail_fn> if
+ * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,
+ * or anything the slow path function returns.
+ */
+static inline int __mutex_fastpath_lock_retval_arg(atomic_t *count,
+				void *arg, int (*fail_fn)(atomic_t *, void*))
+{
+	if (unlikely(ia64_fetchadd4_acq(count, -1) != 1))
+		return fail_fn(count, arg);
+	else
+		return 0;
+}
+
+/**
  *  __mutex_fastpath_unlock - try to promote the count from 0 to 1
  *  @count: pointer of type atomic_t
  *  @fail_fn: function to call if the original value was not 0
diff --git a/arch/powerpc/include/asm/mutex.h b/arch/powerpc/include/asm/mutex.h
index 5399f7e..df4bcff 100644
--- a/arch/powerpc/include/asm/mutex.h
+++ b/arch/powerpc/include/asm/mutex.h
@@ -97,6 +97,26 @@ __mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
 }
 
 /**
+ *  __mutex_fastpath_lock_retval_arg - try to take the lock by moving the count
+ *                                     from 1 to a 0 value
+ *  @count: pointer of type atomic_t
+ *  @arg: argument to pass along if fastpath fails.
+ *  @fail_fn: function to call if the original value was not 1
+ *
+ * Change the count from 1 to a value lower than 1, and call <fail_fn> if
+ * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,
+ * or anything the slow path function returns.
+ */
+static inline int __mutex_fastpath_lock_retval_arg(atomic_t *count,
+				void *arg, int (*fail_fn)(atomic_t *, void*))
+{
+	if (unlikely(__mutex_dec_return_lock(count) < 0))
+		return fail_fn(count, arg);
+	else
+		return 0;
+}
+
+/**
  *  __mutex_fastpath_unlock - try to promote the count from 0 to 1
  *  @count: pointer of type atomic_t
  *  @fail_fn: function to call if the original value was not 0
diff --git a/arch/sh/include/asm/mutex-llsc.h b/arch/sh/include/asm/mutex-llsc.h
index 090358a..b68dd6d 100644
--- a/arch/sh/include/asm/mutex-llsc.h
+++ b/arch/sh/include/asm/mutex-llsc.h
@@ -56,6 +56,26 @@ __mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
 	return __res;
 }
 
+static inline int __mutex_fastpath_lock_retval_arg(atomic_t *count,
+				void *arg, int (*fail_fn)(atomic_t *, void *))
+{
+	int __done, __res;
+
+	__asm__ __volatile__ (
+		"movli.l	@%2, %0	\n"
+		"add		#-1, %0	\n"
+		"movco.l	%0, @%2	\n"
+		"movt		%1	\n"
+		: "=&z" (__res), "=&r" (__done)
+		: "r" (&(count)->counter)
+		: "t");
+
+	if (unlikely(!__done || __res != 0))
+		__res = fail_fn(count, arg);
+
+	return __res;
+}
+
 static inline void
 __mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
 {
diff --git a/arch/x86/include/asm/mutex_32.h b/arch/x86/include/asm/mutex_32.h
index 03f90c8..34f77f9 100644
--- a/arch/x86/include/asm/mutex_32.h
+++ b/arch/x86/include/asm/mutex_32.h
@@ -58,6 +58,26 @@ static inline int __mutex_fastpath_lock_retval(atomic_t *count,
 }
 
 /**
+ *  __mutex_fastpath_lock_retval_arg - try to take the lock by moving the count
+ *                                     from 1 to a 0 value
+ *  @count: pointer of type atomic_t
+ *  @arg: argument to pass along if fastpath fails.
+ *  @fail_fn: function to call if the original value was not 1
+ *
+ * Change the count from 1 to a value lower than 1, and call <fail_fn> if
+ * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,
+ * or anything the slow path function returns.
+ */
+static inline int __mutex_fastpath_lock_retval_arg(atomic_t *count,
+				void *arg, int (*fail_fn)(atomic_t *, void*))
+{
+	if (unlikely(atomic_dec_return(count) < 0))
+		return fail_fn(count, arg);
+	else
+		return 0;
+}
+
+/**
  *  __mutex_fastpath_unlock - try to promote the mutex from 0 to 1
  *  @count: pointer of type atomic_t
  *  @fail_fn: function to call if the original value was not 0
diff --git a/arch/x86/include/asm/mutex_64.h b/arch/x86/include/asm/mutex_64.h
index 68a87b0..148249e 100644
--- a/arch/x86/include/asm/mutex_64.h
+++ b/arch/x86/include/asm/mutex_64.h
@@ -53,6 +53,26 @@ static inline int __mutex_fastpath_lock_retval(atomic_t *count,
 }
 
 /**
+ *  __mutex_fastpath_lock_retval_arg - try to take the lock by moving the count
+ *                                     from 1 to a 0 value
+ *  @count: pointer of type atomic_t
+ *  @arg: argument to pass along if fastpath fails.
+ *  @fail_fn: function to call if the original value was not 1
+ *
+ * Change the count from 1 to a value lower than 1, and call <fail_fn> if
+ * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,
+ * or anything the slow path function returns.
+ */
+static inline int __mutex_fastpath_lock_retval_arg(atomic_t *count,
+				void *arg, int (*fail_fn)(atomic_t *, void*))
+{
+	if (unlikely(atomic_dec_return(count) < 0))
+		return fail_fn(count, arg);
+	else
+		return 0;
+}
+
+/**
  * __mutex_fastpath_unlock - increment and call function if nonpositive
  * @v: pointer of type atomic_t
  * @fail_fn: function to call if the result is nonpositive
diff --git a/include/asm-generic/mutex-dec.h b/include/asm-generic/mutex-dec.h
index f104af7..f5d027e 100644
--- a/include/asm-generic/mutex-dec.h
+++ b/include/asm-generic/mutex-dec.h
@@ -43,6 +43,26 @@ __mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
 }
 
 /**
+ *  __mutex_fastpath_lock_retval_arg - try to take the lock by moving the count
+ *                                     from 1 to a 0 value
+ *  @count: pointer of type atomic_t
+ *  @arg: argument to pass along if fastpath fails.
+ *  @fail_fn: function to call if the original value was not 1
+ *
+ * Change the count from 1 to a value lower than 1, and call <fail_fn> if
+ * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,
+ * or anything the slow path function returns.
+ */
+static inline int
+__mutex_fastpath_lock_retval_arg(atomic_t *count, void *arg,
+				 int (*fail_fn)(atomic_t *, void*))
+{
+	if (unlikely(atomic_dec_return(count) < 0))
+		return fail_fn(count, arg);
+	return 0;
+}
+
+/**
  *  __mutex_fastpath_unlock - try to promote the count from 0 to 1
  *  @count: pointer of type atomic_t
  *  @fail_fn: function to call if the original value was not 0
diff --git a/include/asm-generic/mutex-null.h b/include/asm-generic/mutex-null.h
index e1bbbc7..991e9c3 100644
--- a/include/asm-generic/mutex-null.h
+++ b/include/asm-generic/mutex-null.h
@@ -12,6 +12,7 @@
 
 #define __mutex_fastpath_lock(count, fail_fn)		fail_fn(count)
 #define __mutex_fastpath_lock_retval(count, fail_fn)	fail_fn(count)
+#define __mutex_fastpath_lock_retval_arg(count, arg, fail_fn)	fail_fn(count, arg)
 #define __mutex_fastpath_unlock(count, fail_fn)		fail_fn(count)
 #define __mutex_fastpath_trylock(count, fail_fn)	fail_fn(count)
 #define __mutex_slowpath_needs_to_unlock()		1
diff --git a/include/asm-generic/mutex-xchg.h b/include/asm-generic/mutex-xchg.h
index c04e0db..d9cc971 100644
--- a/include/asm-generic/mutex-xchg.h
+++ b/include/asm-generic/mutex-xchg.h
@@ -55,6 +55,27 @@ __mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
 }
 
 /**
+ *  __mutex_fastpath_lock_retval_arg - try to take the lock by moving the count
+ *                                     from 1 to a 0 value
+ *  @count: pointer of type atomic_t
+ *  @arg: argument to pass along if fastpath fails.
+ *  @fail_fn: function to call if the original value was not 1
+ *
+ * Change the count from 1 to a value lower than 1, and call <fail_fn> if
+ * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,
+ * or anything the slow path function returns.
+ */
+static inline int
+__mutex_fastpath_lock_retval_arg(atomic_t *count, void *arg,
+				 int (*fail_fn)(atomic_t *, void*))
+{
+	if (unlikely(atomic_xchg(count, 0) != 1))
+		if (likely(atomic_xchg(count, -1) != 1))
+			return fail_fn(count, arg);
+	return 0;
+}
+
+/**
  *  __mutex_fastpath_unlock - try to promote the mutex from 0 to 1
  *  @count: pointer of type atomic_t
  *  @fail_fn: function to call if the original value was not 0