Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
diff --git a/include/asm-i386/semaphore.h b/include/asm-i386/semaphore.h
new file mode 100644
index 0000000..ea563da
--- /dev/null
+++ b/include/asm-i386/semaphore.h
@@ -0,0 +1,194 @@
+#ifndef _I386_SEMAPHORE_H
+#define _I386_SEMAPHORE_H
+
+#include <linux/linkage.h>
+
+#ifdef __KERNEL__
+
+/*
+ * 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.
+ * Modified 1999-02-14 by Andrea Arcangeli, split the sched.c helper
+ * functions in asm/sempahore-helper.h while fixing a
+ * potential and subtle race discovered by Ulrich Schmid
+ * in down_interruptible(). Since I started to play here I
+ * also implemented the `trylock' semaphore operation.
+ * 1999-07-02 Artur Skawina <skawina@geocities.com>
+ * Optimized "0(ecx)" -> "(ecx)" (the assembler does not
+ * do this). Changed calling sequences from push/jmp to
+ * traditional call/ret.
+ * Modified 2001-01-01 Andreas Franck <afranck@gmx.de>
+ * Some hacks to ensure compatibility with recent
+ * GCC snapshots, to avoid stack corruption when compiling
+ * with -fomit-frame-pointer. It's not sure if this will
+ * be fixed in GCC, as our previous implementation was a
+ * bit dubious.
+ *
+ * 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>
+#include <linux/wait.h>
+#include <linux/rwsem.h>
+
+struct semaphore {
+ atomic_t count;
+ int sleepers;
+ wait_queue_head_t wait;
+};
+
+
+#define __SEMAPHORE_INITIALIZER(name, n) \
+{ \
+ .count = ATOMIC_INIT(n), \
+ .sleepers = 0, \
+ .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait) \
+}
+
+#define __MUTEX_INITIALIZER(name) \
+ __SEMAPHORE_INITIALIZER(name,1)
+
+#define __DECLARE_SEMAPHORE_GENERIC(name,count) \
+ struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
+
+#define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
+#define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
+
+static inline void sema_init (struct semaphore *sem, int val)
+{
+/*
+ * *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
+ *
+ * i'd rather use the more flexible initialization above, but sadly
+ * GCC 2.7.2.3 emits a bogus warning. EGCS doesn't. Oh well.
+ */
+ atomic_set(&sem->count, val);
+ sem->sleepers = 0;
+ init_waitqueue_head(&sem->wait);
+}
+
+static inline void init_MUTEX (struct semaphore *sem)
+{
+ sema_init(sem, 1);
+}
+
+static inline void init_MUTEX_LOCKED (struct semaphore *sem)
+{
+ sema_init(sem, 0);
+}
+
+fastcall void __down_failed(void /* special register calling convention */);
+fastcall int __down_failed_interruptible(void /* params in registers */);
+fastcall int __down_failed_trylock(void /* params in registers */);
+fastcall void __up_wakeup(void /* special register calling convention */);
+
+/*
+ * 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/kernel/semaphore.c
+ */
+static inline void down(struct semaphore * sem)
+{
+ might_sleep();
+ __asm__ __volatile__(
+ "# atomic down operation\n\t"
+ LOCK "decl %0\n\t" /* --sem->count */
+ "js 2f\n"
+ "1:\n"
+ LOCK_SECTION_START("")
+ "2:\tlea %0,%%eax\n\t"
+ "call __down_failed\n\t"
+ "jmp 1b\n"
+ LOCK_SECTION_END
+ :"=m" (sem->count)
+ :
+ :"memory","ax");
+}
+
+/*
+ * Interruptible try to acquire a semaphore. If we obtained
+ * it, return zero. If we were interrupted, returns -EINTR
+ */
+static inline int down_interruptible(struct semaphore * sem)
+{
+ int result;
+
+ might_sleep();
+ __asm__ __volatile__(
+ "# atomic interruptible down operation\n\t"
+ LOCK "decl %1\n\t" /* --sem->count */
+ "js 2f\n\t"
+ "xorl %0,%0\n"
+ "1:\n"
+ LOCK_SECTION_START("")
+ "2:\tlea %1,%%eax\n\t"
+ "call __down_failed_interruptible\n\t"
+ "jmp 1b\n"
+ LOCK_SECTION_END
+ :"=a" (result), "=m" (sem->count)
+ :
+ :"memory");
+ return result;
+}
+
+/*
+ * Non-blockingly attempt to down() a semaphore.
+ * Returns zero if we acquired it
+ */
+static inline int down_trylock(struct semaphore * sem)
+{
+ int result;
+
+ __asm__ __volatile__(
+ "# atomic interruptible down operation\n\t"
+ LOCK "decl %1\n\t" /* --sem->count */
+ "js 2f\n\t"
+ "xorl %0,%0\n"
+ "1:\n"
+ LOCK_SECTION_START("")
+ "2:\tlea %1,%%eax\n\t"
+ "call __down_failed_trylock\n\t"
+ "jmp 1b\n"
+ LOCK_SECTION_END
+ :"=a" (result), "=m" (sem->count)
+ :
+ :"memory");
+ return result;
+}
+
+/*
+ * Note! This is subtle. We jump to wake people up only if
+ * the semaphore was negative (== somebody was waiting on it).
+ * The default case (no contention) will result in NO
+ * jumps for both down() and up().
+ */
+static inline void up(struct semaphore * sem)
+{
+ __asm__ __volatile__(
+ "# atomic up operation\n\t"
+ LOCK "incl %0\n\t" /* ++sem->count */
+ "jle 2f\n"
+ "1:\n"
+ LOCK_SECTION_START("")
+ "2:\tlea %0,%%eax\n\t"
+ "call __up_wakeup\n\t"
+ "jmp 1b\n"
+ LOCK_SECTION_END
+ ".subsection 0\n"
+ :"=m" (sem->count)
+ :
+ :"memory","ax");
+}
+
+#endif
+#endif
