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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /include/asm-i386/rwlock.h
Linux-2.6.12-rc2v2.6.12-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!
Diffstat (limited to 'include/asm-i386/rwlock.h')
-rw-r--r--include/asm-i386/rwlock.h71
1 files changed, 71 insertions, 0 deletions
diff --git a/include/asm-i386/rwlock.h b/include/asm-i386/rwlock.h
new file mode 100644
index 000000000000..b57cc7afdf7e
--- /dev/null
+++ b/include/asm-i386/rwlock.h
@@ -0,0 +1,71 @@
1/* include/asm-i386/rwlock.h
2 *
3 * Helpers used by both rw spinlocks and rw semaphores.
4 *
5 * Based in part on code from semaphore.h and
6 * spinlock.h Copyright 1996 Linus Torvalds.
7 *
8 * Copyright 1999 Red Hat, Inc.
9 *
10 * Written by Benjamin LaHaise.
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License
14 * as published by the Free Software Foundation; either version
15 * 2 of the License, or (at your option) any later version.
16 */
17#ifndef _ASM_I386_RWLOCK_H
18#define _ASM_I386_RWLOCK_H
19
20#define RW_LOCK_BIAS 0x01000000
21#define RW_LOCK_BIAS_STR "0x01000000"
22
23#define __build_read_lock_ptr(rw, helper) \
24 asm volatile(LOCK "subl $1,(%0)\n\t" \
25 "jns 1f\n" \
26 "call " helper "\n\t" \
27 "1:\n" \
28 ::"a" (rw) : "memory")
29
30#define __build_read_lock_const(rw, helper) \
31 asm volatile(LOCK "subl $1,%0\n\t" \
32 "jns 1f\n" \
33 "pushl %%eax\n\t" \
34 "leal %0,%%eax\n\t" \
35 "call " helper "\n\t" \
36 "popl %%eax\n\t" \
37 "1:\n" \
38 :"=m" (*(volatile int *)rw) : : "memory")
39
40#define __build_read_lock(rw, helper) do { \
41 if (__builtin_constant_p(rw)) \
42 __build_read_lock_const(rw, helper); \
43 else \
44 __build_read_lock_ptr(rw, helper); \
45 } while (0)
46
47#define __build_write_lock_ptr(rw, helper) \
48 asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",(%0)\n\t" \
49 "jz 1f\n" \
50 "call " helper "\n\t" \
51 "1:\n" \
52 ::"a" (rw) : "memory")
53
54#define __build_write_lock_const(rw, helper) \
55 asm volatile(LOCK "subl $" RW_LOCK_BIAS_STR ",%0\n\t" \
56 "jz 1f\n" \
57 "pushl %%eax\n\t" \
58 "leal %0,%%eax\n\t" \
59 "call " helper "\n\t" \
60 "popl %%eax\n\t" \
61 "1:\n" \
62 :"=m" (*(volatile int *)rw) : : "memory")
63
64#define __build_write_lock(rw, helper) do { \
65 if (__builtin_constant_p(rw)) \
66 __build_write_lock_const(rw, helper); \
67 else \
68 __build_write_lock_ptr(rw, helper); \
69 } while (0)
70
71#endif