From fb1c8f93d869b34cacb8b8932e2b83d96a19d720 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sat, 10 Sep 2005 00:25:56 -0700 Subject: [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 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" ia64 fix Signed-off-by: Ingo Molnar Signed-off-by: Arjan van de Ven Signed-off-by: Grant Grundler Cc: Matthew Wilcox Signed-off-by: Hirokazu Takata Signed-off-by: Mikael Pettersson Signed-off-by: Benoit Boissinot Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/spinlock_up.h | 74 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 include/linux/spinlock_up.h (limited to 'include/linux/spinlock_up.h') diff --git a/include/linux/spinlock_up.h b/include/linux/spinlock_up.h new file mode 100644 index 000000000000..31accf2f0b13 --- /dev/null +++ b/include/linux/spinlock_up.h @@ -0,0 +1,74 @@ +#ifndef __LINUX_SPINLOCK_UP_H +#define __LINUX_SPINLOCK_UP_H + +#ifndef __LINUX_SPINLOCK_H +# error "please don't include this file directly" +#endif + +/* + * include/linux/spinlock_up.h - UP-debug version of spinlocks. + * + * portions Copyright 2005, Red Hat, Inc., Ingo Molnar + * Released under the General Public License (GPL). + * + * In the debug case, 1 means unlocked, 0 means locked. (the values + * are inverted, to catch initialization bugs) + * + * No atomicity anywhere, we are on UP. + */ + +#ifdef CONFIG_DEBUG_SPINLOCK + +#define __raw_spin_is_locked(x) ((x)->slock == 0) + +static inline void __raw_spin_lock(raw_spinlock_t *lock) +{ + lock->slock = 0; +} + +static inline void +__raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags) +{ + local_irq_save(flags); + lock->slock = 0; +} + +static inline int __raw_spin_trylock(raw_spinlock_t *lock) +{ + char oldval = lock->slock; + + lock->slock = 0; + + return oldval > 0; +} + +static inline void __raw_spin_unlock(raw_spinlock_t *lock) +{ + lock->slock = 1; +} + +/* + * Read-write spinlocks. No debug version. + */ +#define __raw_read_lock(lock) do { (void)(lock); } while (0) +#define __raw_write_lock(lock) do { (void)(lock); } while (0) +#define __raw_read_trylock(lock) ({ (void)(lock); 1; }) +#define __raw_write_trylock(lock) ({ (void)(lock); 1; }) +#define __raw_read_unlock(lock) do { (void)(lock); } while (0) +#define __raw_write_unlock(lock) do { (void)(lock); } while (0) + +#else /* DEBUG_SPINLOCK */ +#define __raw_spin_is_locked(lock) ((void)(lock), 0) +/* for sched.c and kernel_lock.c: */ +# define __raw_spin_lock(lock) do { (void)(lock); } while (0) +# define __raw_spin_unlock(lock) do { (void)(lock); } while (0) +# define __raw_spin_trylock(lock) ({ (void)(lock); 1; }) +#endif /* DEBUG_SPINLOCK */ + +#define __raw_read_can_lock(lock) (((void)(lock), 1)) +#define __raw_write_can_lock(lock) (((void)(lock), 1)) + +#define __raw_spin_unlock_wait(lock) \ + do { cpu_relax(); } while (__raw_spin_is_locked(lock)) + +#endif /* __LINUX_SPINLOCK_UP_H */ -- cgit v1.2.3-59-g8ed1b