[PATCH] triple_down in fs.h

[Per Persson]

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Cleaned up some code.
Hope I didn't break anything.

[PATCH attached]

Per Persson
[e-mail]

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--- include/linux/fs.h.orig	Mon Sep 24 12:43:10 2001=0A=
+++ include/linux/fs.h	Mon Sep 24 16:37:39 2001=0A=
@@ -1441,14 +1441,22 @@=0A=
 /*=0A=
  * Whee.. Deadlock country. Happily there are only two VFS=0A=
  * operations that does this..=0A=
+ *=0A=
+ * {double,triple}_down modified by Per Persson in September, 2001=0A=
  */=0A=
+=0A=
+#define exch(x,y)			\=0A=
+do {					\=0A=
+	typeof(x) __tmp__ =3D (x);	\=0A=
+	(x) =3D (y);			\=0A=
+	(y) =3D __tmp__;			\=0A=
+} while(0)=0A=
+=0A=
 static inline void double_down(struct semaphore *s1, struct semaphore =
*s2)=0A=
 {=0A=
 	if (s1 !=3D s2) {=0A=
-		if ((unsigned long) s1 < (unsigned long) s2) {=0A=
-			struct semaphore *tmp =3D s2;=0A=
-			s2 =3D s1; s1 =3D tmp;=0A=
-		}=0A=
+		if ((ulong) s1 < (ulong) s2)=0A=
+			exch(s1, s2);		// s1 > s2=0A=
 		down(s1);=0A=
 	}=0A=
 	down(s2);=0A=
@@ -1458,9 +1466,11 @@=0A=
  * Ewwwwwwww... _triple_ lock. We are guaranteed that the 3rd argument =
is=0A=
  * not equal to 1st and not equal to 2nd - the first case (target is =
parent of=0A=
  * source) would be already caught, the second is plain impossible =
(target is=0A=
- * its own parent and that case would be caught even earlier). Very =
messy.=0A=
- * I _think_ that it works, but no warranties - please, look it through.=0A=
- * Pox on bloody lusers who mandated overwriting rename() for =
directories...=0A=
+ * its own parent and that case would be caught even earlier).=0A=
+ *=0A=
+ * Hopefully it does the same thing as the old code,=0A=
+ * but in a cleaner and more efficient way.=0A=
+ *     /Per=0A=
  */=0A=
 =0A=
 static inline void triple_down(struct semaphore *s1,=0A=
@@ -1468,30 +1478,14 @@=0A=
 			       struct semaphore *s3)=0A=
 {=0A=
 	if (s1 !=3D s2) {=0A=
-		if ((unsigned long) s1 < (unsigned long) s2) {=0A=
-			if ((unsigned long) s1 < (unsigned long) s3) {=0A=
-				struct semaphore *tmp =3D s3;=0A=
-				s3 =3D s1; s1 =3D tmp;=0A=
-			}=0A=
-			if ((unsigned long) s1 < (unsigned long) s2) {=0A=
-				struct semaphore *tmp =3D s2;=0A=
-				s2 =3D s1; s1 =3D tmp;=0A=
-			}=0A=
-		} else {=0A=
-			if ((unsigned long) s1 < (unsigned long) s3) {=0A=
-				struct semaphore *tmp =3D s3;=0A=
-				s3 =3D s1; s1 =3D tmp;=0A=
-			}=0A=
-			if ((unsigned long) s2 < (unsigned long) s3) {=0A=
-				struct semaphore *tmp =3D s3;=0A=
-				s3 =3D s2; s2 =3D tmp;=0A=
-			}=0A=
-		}=0A=
+		if ((ulong) s1 < (ulong) s2)=0A=
+			exch(s1, s2);		// s1 > s2=0A=
+		if ((ulong) s1 < (ulong) s3)=0A=
+			exch(s1, s3);		// s1 > s2,  s1 > s3=0A=
 		down(s1);=0A=
-	} else if ((unsigned long) s2 < (unsigned long) s3) {=0A=
-		struct semaphore *tmp =3D s3;=0A=
-		s3 =3D s2; s2 =3D tmp;=0A=
 	}=0A=
+	if((ulong) s2 < (ulong) s3)=0A=
+		exch(s2, s3);			// s2 > s3=0A=
 	down(s2);=0A=
 	down(s3);=0A=
 }=0A=

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