patch-2.0.30 linux/include/asm-i386/semaphore.h

• Lines: 104
• Date: Tue Apr 8 08:47:46 1997
• Orig file: v2.0.29/linux/include/asm-i386/semaphore.h
• Orig date: Thu Feb 6 07:21:29 1997

diff -u --recursive --new-file v2.0.29/linux/include/asm-i386/semaphore.h linux/include/asm-i386/semaphore.h
@@ -2,21 +2,33 @@
 #define _I386_SEMAPHORE_H
 
 #include <linux/linkage.h>
+#include <asm/system.h>
 
 /*
  * SMP- and interrupt-safe semaphores..
  *
  * (C) Copyright 1996 Linus Torvalds
+ *
+ * Modified 1996-12-23 by Dave Grothe <dave@gcom.com> to fix bugs in
+ *                     the original code and to make semaphore waits
+ *                     interruptible so that processes waiting on
+ *                     semaphores can be killed.
+ *
+ * If you would like to see an analysis of this implementation, please
+ * ftp to gcom.com and download the file
+ * /pub/linux/src/semaphore/semaphore-2.0.24.tar.gz.
+ *
  */
 
 struct semaphore {
 	int count;
-	int waiting;
+	int waking;
+	int lock ;			/* to make waking testing atomic */
 	struct wait_queue * wait;
 };
 
-#define MUTEX ((struct semaphore) { 1, 0, NULL })
-#define MUTEX_LOCKED ((struct semaphore) { 0, 0, NULL })
+#define MUTEX ((struct semaphore) { 1, 0, 0, NULL })
+#define MUTEX_LOCKED ((struct semaphore) { 0, 0, 0, NULL })
 
 asmlinkage void down_failed(void /* special register calling convention */);
 asmlinkage void up_wakeup(void /* special register calling convention */);
@@ -32,17 +44,62 @@
 extern inline void down(struct semaphore * sem)
 {
 	__asm__ __volatile__(
-		"# atomic down operation\n"
-		"1:\n\t"
-		"movl $1b,%%eax\n\t"
+		"# atomic down operation\n\t"
+		"movl $1f,%%eax\n\t"
 #ifdef __SMP__
 		"lock ; "
 #endif
 		"decl 0(%0)\n\t"
-		"js " SYMBOL_NAME_STR(down_failed)
+		"js " SYMBOL_NAME_STR(down_failed) "\n"
+		"1:\n"
 		:/* no outputs */
 		:"c" (sem)
 		:"ax","dx","memory");
+}
+
+/*
+ * Primitives to spin on a lock.  Needed only for SMP version.
+ */
+extern inline void get_buzz_lock(int *lock_ptr)
+{
+#ifdef __SMP__
+        while (xchg(lock_ptr,1) != 0) ;
+#endif
+} /* get_buzz_lock */
+
+extern inline void give_buzz_lock(int *lock_ptr)
+{
+#ifdef __SMP__
+        *lock_ptr = 0 ;
+#endif
+} /* give_buzz_lock */
+
+asmlinkage int down_failed_interruptible(void);  /* params in registers */
+
+/*
+ * This version waits in interruptible state so that the waiting
+ * process can be killed.  The down_failed_interruptible routine
+ * returns negative for signalled and zero for semaphore acquired.
+ */
+extern inline int down_interruptible(struct semaphore * sem)
+{
+	int	ret ;
+
+        __asm__ __volatile__(
+                "# atomic interruptible down operation\n\t"
+                "movl $2f,%%eax\n\t"
+#ifdef __SMP__
+                "lock ; "
+#endif
+                "decl 0(%1)\n\t"
+                "js " SYMBOL_NAME_STR(down_failed_interruptible) "\n\t"
+                "xorl %%eax,%%eax\n"
+                "2:\n"
+                :"=a" (ret)
+                :"c" (sem)
+                :"ax","dx","memory");
+
+	return(ret) ;
 }
 
 /*