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authorIngo Molnar <mingo@elte.hu>2005-09-10 03:25:56 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-10 13:06:21 -0400
commitfb1c8f93d869b34cacb8b8932e2b83d96a19d720 (patch)
treea006d078aa02e421a7dc4793c335308204859d36 /include/linux/bit_spinlock.h
parent4327edf6b8a7ac7dce144313947995538842d8fd (diff)
[PATCH] spinlock consolidation
This patch (written by me and also containing many suggestions of Arjan van de Ven) does a major cleanup of the spinlock code. It does the following things: - consolidates and enhances the spinlock/rwlock debugging code - simplifies the asm/spinlock.h files - encapsulates the raw spinlock type and moves generic spinlock features (such as ->break_lock) into the generic code. - cleans up the spinlock code hierarchy to get rid of the spaghetti. Most notably there's now only a single variant of the debugging code, located in lib/spinlock_debug.c. (previously we had one SMP debugging variant per architecture, plus a separate generic one for UP builds) Also, i've enhanced the rwlock debugging facility, it will now track write-owners. There is new spinlock-owner/CPU-tracking on SMP builds too. All locks have lockup detection now, which will work for both soft and hard spin/rwlock lockups. The arch-level include files now only contain the minimally necessary subset of the spinlock code - all the rest that can be generalized now lives in the generic headers: include/asm-i386/spinlock_types.h | 16 include/asm-x86_64/spinlock_types.h | 16 I have also split up the various spinlock variants into separate files, making it easier to see which does what. The new layout is: SMP | UP ----------------------------|----------------------------------- asm/spinlock_types_smp.h | linux/spinlock_types_up.h linux/spinlock_types.h | linux/spinlock_types.h asm/spinlock_smp.h | linux/spinlock_up.h linux/spinlock_api_smp.h | linux/spinlock_api_up.h linux/spinlock.h | linux/spinlock.h /* * here's the role of the various spinlock/rwlock related include files: * * on SMP builds: * * asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the * initializers * * linux/spinlock_types.h: * defines the generic type and initializers * * asm/spinlock.h: contains the __raw_spin_*()/etc. lowlevel * implementations, mostly inline assembly code * * (also included on UP-debug builds:) * * linux/spinlock_api_smp.h: * contains the prototypes for the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. * * on UP builds: * * linux/spinlock_type_up.h: * contains the generic, simplified UP spinlock type. * (which is an empty structure on non-debug builds) * * linux/spinlock_types.h: * defines the generic type and initializers * * linux/spinlock_up.h: * contains the __raw_spin_*()/etc. version of UP * builds. (which are NOPs on non-debug, non-preempt * builds) * * (included on UP-non-debug builds:) * * linux/spinlock_api_up.h: * builds the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. */ All SMP and UP architectures are converted by this patch. arm, i386, ia64, ppc, ppc64, s390/s390x, x64 was build-tested via crosscompilers. m32r, mips, sh, sparc, have not been tested yet, but should be mostly fine. From: Grant Grundler <grundler@parisc-linux.org> Booted and lightly tested on a500-44 (64-bit, SMP kernel, dual CPU). Builds 32-bit SMP kernel (not booted or tested). I did not try to build non-SMP kernels. That should be trivial to fix up later if necessary. I converted bit ops atomic_hash lock to raw_spinlock_t. Doing so avoids some ugly nesting of linux/*.h and asm/*.h files. Those particular locks are well tested and contained entirely inside arch specific code. I do NOT expect any new issues to arise with them. If someone does ever need to use debug/metrics with them, then they will need to unravel this hairball between spinlocks, atomic ops, and bit ops that exist only because parisc has exactly one atomic instruction: LDCW (load and clear word). From: "Luck, Tony" <tony.luck@intel.com> ia64 fix Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjanv@infradead.org> Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Cc: Matthew Wilcox <willy@debian.org> Signed-off-by: Hirokazu Takata <takata@linux-m32r.org> Signed-off-by: Mikael Pettersson <mikpe@csd.uu.se> Signed-off-by: Benoit Boissinot <benoit.boissinot@ens-lyon.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux/bit_spinlock.h')
-rw-r--r--include/linux/bit_spinlock.h77
1 files changed, 77 insertions, 0 deletions
diff --git a/include/linux/bit_spinlock.h b/include/linux/bit_spinlock.h
new file mode 100644
index 000000000000..6b20af0bbb79
--- /dev/null
+++ b/include/linux/bit_spinlock.h
@@ -0,0 +1,77 @@
1#ifndef __LINUX_BIT_SPINLOCK_H
2#define __LINUX_BIT_SPINLOCK_H
3
4/*
5 * bit-based spin_lock()
6 *
7 * Don't use this unless you really need to: spin_lock() and spin_unlock()
8 * are significantly faster.
9 */
10static inline void bit_spin_lock(int bitnum, unsigned long *addr)
11{
12 /*
13 * Assuming the lock is uncontended, this never enters
14 * the body of the outer loop. If it is contended, then
15 * within the inner loop a non-atomic test is used to
16 * busywait with less bus contention for a good time to
17 * attempt to acquire the lock bit.
18 */
19 preempt_disable();
20#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
21 while (test_and_set_bit(bitnum, addr)) {
22 while (test_bit(bitnum, addr)) {
23 preempt_enable();
24 cpu_relax();
25 preempt_disable();
26 }
27 }
28#endif
29 __acquire(bitlock);
30}
31
32/*
33 * Return true if it was acquired
34 */
35static inline int bit_spin_trylock(int bitnum, unsigned long *addr)
36{
37 preempt_disable();
38#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
39 if (test_and_set_bit(bitnum, addr)) {
40 preempt_enable();
41 return 0;
42 }
43#endif
44 __acquire(bitlock);
45 return 1;
46}
47
48/*
49 * bit-based spin_unlock()
50 */
51static inline void bit_spin_unlock(int bitnum, unsigned long *addr)
52{
53#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
54 BUG_ON(!test_bit(bitnum, addr));
55 smp_mb__before_clear_bit();
56 clear_bit(bitnum, addr);
57#endif
58 preempt_enable();
59 __release(bitlock);
60}
61
62/*
63 * Return true if the lock is held.
64 */
65static inline int bit_spin_is_locked(int bitnum, unsigned long *addr)
66{
67#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
68 return test_bit(bitnum, addr);
69#elif defined CONFIG_PREEMPT
70 return preempt_count();
71#else
72 return 1;
73#endif
74}
75
76#endif /* __LINUX_BIT_SPINLOCK_H */
77