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![Ingo Molnar](/assets/img/avatar_default.png)
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>
77 lines
1.7 KiB
C
77 lines
1.7 KiB
C
#ifndef __LINUX_BIT_SPINLOCK_H
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#define __LINUX_BIT_SPINLOCK_H
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/*
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* bit-based spin_lock()
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*
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* Don't use this unless you really need to: spin_lock() and spin_unlock()
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* are significantly faster.
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*/
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static inline void bit_spin_lock(int bitnum, unsigned long *addr)
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{
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/*
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* Assuming the lock is uncontended, this never enters
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* the body of the outer loop. If it is contended, then
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* within the inner loop a non-atomic test is used to
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* busywait with less bus contention for a good time to
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* attempt to acquire the lock bit.
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*/
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preempt_disable();
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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while (test_and_set_bit(bitnum, addr)) {
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while (test_bit(bitnum, addr)) {
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preempt_enable();
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cpu_relax();
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preempt_disable();
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}
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}
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#endif
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__acquire(bitlock);
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}
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/*
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* Return true if it was acquired
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*/
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static inline int bit_spin_trylock(int bitnum, unsigned long *addr)
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{
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preempt_disable();
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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if (test_and_set_bit(bitnum, addr)) {
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preempt_enable();
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return 0;
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}
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#endif
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__acquire(bitlock);
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return 1;
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}
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/*
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* bit-based spin_unlock()
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*/
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static inline void bit_spin_unlock(int bitnum, unsigned long *addr)
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{
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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BUG_ON(!test_bit(bitnum, addr));
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smp_mb__before_clear_bit();
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clear_bit(bitnum, addr);
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#endif
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preempt_enable();
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__release(bitlock);
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}
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/*
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* Return true if the lock is held.
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*/
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static inline int bit_spin_is_locked(int bitnum, unsigned long *addr)
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{
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#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
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return test_bit(bitnum, addr);
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#elif defined CONFIG_PREEMPT
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return preempt_count();
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#else
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return 1;
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#endif
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}
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#endif /* __LINUX_BIT_SPINLOCK_H */
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