diff options
author | Ingo Molnar <mingo@elte.hu> | 2005-09-10 00:25:56 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-10 10:06:21 -0700 |
commit | fb1c8f93d869b34cacb8b8932e2b83d96a19d720 (patch) | |
tree | a006d078aa02e421a7dc4793c335308204859d36 /include/linux/bit_spinlock.h | |
parent | 4327edf6b8a7ac7dce144313947995538842d8fd (diff) | |
download | linux-stable-fb1c8f93d869b34cacb8b8932e2b83d96a19d720.tar.gz linux-stable-fb1c8f93d869b34cacb8b8932e2b83d96a19d720.tar.bz2 linux-stable-fb1c8f93d869b34cacb8b8932e2b83d96a19d720.zip |
[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.h | 77 |
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 @@ +#ifndef __LINUX_BIT_SPINLOCK_H +#define __LINUX_BIT_SPINLOCK_H + +/* + * bit-based spin_lock() + * + * Don't use this unless you really need to: spin_lock() and spin_unlock() + * are significantly faster. + */ +static inline void bit_spin_lock(int bitnum, unsigned long *addr) +{ + /* + * Assuming the lock is uncontended, this never enters + * the body of the outer loop. If it is contended, then + * within the inner loop a non-atomic test is used to + * busywait with less bus contention for a good time to + * attempt to acquire the lock bit. + */ + preempt_disable(); +#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) + while (test_and_set_bit(bitnum, addr)) { + while (test_bit(bitnum, addr)) { + preempt_enable(); + cpu_relax(); + preempt_disable(); + } + } +#endif + __acquire(bitlock); +} + +/* + * Return true if it was acquired + */ +static inline int bit_spin_trylock(int bitnum, unsigned long *addr) +{ + preempt_disable(); +#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) + if (test_and_set_bit(bitnum, addr)) { + preempt_enable(); + return 0; + } +#endif + __acquire(bitlock); + return 1; +} + +/* + * bit-based spin_unlock() + */ +static inline void bit_spin_unlock(int bitnum, unsigned long *addr) +{ +#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) + BUG_ON(!test_bit(bitnum, addr)); + smp_mb__before_clear_bit(); + clear_bit(bitnum, addr); +#endif + preempt_enable(); + __release(bitlock); +} + +/* + * Return true if the lock is held. + */ +static inline int bit_spin_is_locked(int bitnum, unsigned long *addr) +{ +#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) + return test_bit(bitnum, addr); +#elif defined CONFIG_PREEMPT + return preempt_count(); +#else + return 1; +#endif +} + +#endif /* __LINUX_BIT_SPINLOCK_H */ + |