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authorRalf Baechle <ralf@linux-mips.org>1997-04-29 21:13:14 +0000
committer <ralf@linux-mips.org>1997-04-29 21:13:14 +0000
commit19c9bba94152148523ba0f7ef7cffe3d45656b11 (patch)
tree40b1cb534496a7f1ca0f5c314a523c69f1fee464 /include/asm-i386/semaphore.h
parent7206675c40394c78a90e74812bbdbf8cf3cca1be (diff)
Import of Linux/MIPS 2.1.36
Diffstat (limited to 'include/asm-i386/semaphore.h')
-rw-r--r--include/asm-i386/semaphore.h104
1 files changed, 91 insertions, 13 deletions
diff --git a/include/asm-i386/semaphore.h b/include/asm-i386/semaphore.h
index 930b39edb..4395dfce0 100644
--- a/include/asm-i386/semaphore.h
+++ b/include/asm-i386/semaphore.h
@@ -7,42 +7,120 @@
* 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.
+ *
*/
+#include <asm/system.h>
+#include <asm/atomic.h>
+
struct semaphore {
- int count;
- int waiting;
+ atomic_t count;
+ int waking;
struct wait_queue * wait;
};
-#define MUTEX ((struct semaphore) { 1, 0, NULL })
-#define MUTEX_LOCKED ((struct semaphore) { 0, 0, NULL })
+#define MUTEX ((struct semaphore) { ATOMIC_INIT(1), 0, NULL })
+#define MUTEX_LOCKED ((struct semaphore) { ATOMIC_INIT(0), 0, NULL })
asmlinkage void __down_failed(void /* special register calling convention */);
+asmlinkage int __down_failed_interruptible(void /* params in registers */);
asmlinkage void __up_wakeup(void /* special register calling convention */);
extern void __down(struct semaphore * sem);
extern void __up(struct semaphore * sem);
+#define sema_init(sem, val) atomic_set(&((sem)->count), (val))
+
+/*
+ * These two _must_ execute atomically wrt each other.
+ *
+ * This is trivially done with load_locked/store_cond,
+ * but on the x86 we need an external synchronizer.
+ * Currently this is just the global interrupt lock,
+ * bah. Go for a smaller spinlock some day.
+ *
+ * (On the other hand this shouldn't be in any critical
+ * path, so..)
+ */
+static inline void wake_one_more(struct semaphore * sem)
+{
+ unsigned long flags;
+
+ save_flags(flags);
+ cli();
+ sem->waking++;
+ restore_flags(flags);
+}
+
+static inline int waking_non_zero(struct semaphore *sem)
+{
+ unsigned long flags;
+ int ret = 0;
+
+ save_flags(flags);
+ cli();
+ if (sem->waking > 0) {
+ sem->waking--;
+ ret = 1;
+ }
+ restore_flags(flags);
+ return ret;
+}
+
/*
* This is ugly, but we want the default case to fall through.
* "down_failed" is a special asm handler that calls the C
* routine that actually waits. See arch/i386/lib/semaphore.S
*/
-extern __inline__ void down(struct semaphore * sem)
+extern inline void down(struct semaphore * sem)
{
__asm__ __volatile__(
"# atomic down operation\n\t"
+ "movl $1f,%%eax\n\t"
#ifdef __SMP__
"lock ; "
#endif
- "decl %0\n\t"
- "movl $1f,%%eax\n\t"
+ "decl 0(%0)\n\t"
"js " SYMBOL_NAME_STR(__down_failed)
"\n1:"
:/* no outputs */
- :"m" (sem->count), "c" (sem)
- :"ax", "memory");
+ :"c" (sem)
+ :"ax","memory");
+}
+
+/*
+ * 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 $1f,%0\n\t"
+#ifdef __SMP__
+ "lock ; "
+#endif
+ "decl 0(%1)\n\t"
+ "js " SYMBOL_NAME_STR(__down_failed_interruptible) "\n\t"
+ "xorl %0,%0"
+ "\n1:"
+ :"=a" (ret)
+ :"c" (sem)
+ :"memory");
+
+ return ret;
}
/*
@@ -51,19 +129,19 @@ extern __inline__ void down(struct semaphore * sem)
* The default case (no contention) will result in NO
* jumps for both down() and up().
*/
-extern __inline__ void up(struct semaphore * sem)
+extern inline void up(struct semaphore * sem)
{
__asm__ __volatile__(
"# atomic up operation\n\t"
+ "movl $1f,%%eax\n\t"
#ifdef __SMP__
"lock ; "
#endif
- "incl %0\n\t"
- "movl $1f,%%eax\n\t"
+ "incl 0(%0)\n\t"
"jle " SYMBOL_NAME_STR(__up_wakeup)
"\n1:"
:/* no outputs */
- :"m" (sem->count), "c" (sem)
+ :"c" (sem)
:"ax", "memory");
}