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/asm-x86_64/spinlock.h | 164 +++++++++--------------------------- include/asm-x86_64/spinlock_types.h | 20 +++++ 2 files changed, 62 insertions(+), 122 deletions(-) create mode 100644 include/asm-x86_64/spinlock_types.h (limited to 'include/asm-x86_64') diff --git a/include/asm-x86_64/spinlock.h b/include/asm-x86_64/spinlock.h index 5aeb57a3baad..69636831ad2f 100644 --- a/include/asm-x86_64/spinlock.h +++ b/include/asm-x86_64/spinlock.h @@ -6,47 +6,21 @@ #include #include -extern int printk(const char * fmt, ...) - __attribute__ ((format (printf, 1, 2))); - /* * Your basic SMP spinlocks, allowing only a single CPU anywhere - */ - -typedef struct { - volatile unsigned int lock; -#ifdef CONFIG_DEBUG_SPINLOCK - unsigned magic; -#endif -#ifdef CONFIG_PREEMPT - unsigned int break_lock; -#endif -} spinlock_t; - -#define SPINLOCK_MAGIC 0xdead4ead - -#ifdef CONFIG_DEBUG_SPINLOCK -#define SPINLOCK_MAGIC_INIT , SPINLOCK_MAGIC -#else -#define SPINLOCK_MAGIC_INIT /* */ -#endif - -#define SPIN_LOCK_UNLOCKED (spinlock_t) { 1 SPINLOCK_MAGIC_INIT } - -#define spin_lock_init(x) do { *(x) = SPIN_LOCK_UNLOCKED; } while(0) - -/* + * * Simple spin lock operations. There are two variants, one clears IRQ's * on the local processor, one does not. * * We make no fairness assumptions. They have a cost. + * + * (the type definitions are in asm/spinlock_types.h) */ -#define spin_is_locked(x) (*(volatile signed char *)(&(x)->lock) <= 0) -#define spin_unlock_wait(x) do { barrier(); } while(spin_is_locked(x)) -#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock) +#define __raw_spin_is_locked(x) \ + (*(volatile signed char *)(&(x)->slock) <= 0) -#define spin_lock_string \ +#define __raw_spin_lock_string \ "\n1:\t" \ "lock ; decb %0\n\t" \ "js 2f\n" \ @@ -58,74 +32,40 @@ typedef struct { "jmp 1b\n" \ LOCK_SECTION_END -/* - * This works. Despite all the confusion. - * (except on PPro SMP or if we are using OOSTORE) - * (PPro errata 66, 92) - */ - -#if !defined(CONFIG_X86_OOSTORE) && !defined(CONFIG_X86_PPRO_FENCE) - -#define spin_unlock_string \ +#define __raw_spin_unlock_string \ "movb $1,%0" \ - :"=m" (lock->lock) : : "memory" - - -static inline void _raw_spin_unlock(spinlock_t *lock) -{ -#ifdef CONFIG_DEBUG_SPINLOCK - BUG_ON(lock->magic != SPINLOCK_MAGIC); - assert_spin_locked(lock); -#endif - __asm__ __volatile__( - spin_unlock_string - ); -} - -#else - -#define spin_unlock_string \ - "xchgb %b0, %1" \ - :"=q" (oldval), "=m" (lock->lock) \ - :"0" (oldval) : "memory" + :"=m" (lock->slock) : : "memory" -static inline void _raw_spin_unlock(spinlock_t *lock) +static inline void __raw_spin_lock(raw_spinlock_t *lock) { - char oldval = 1; -#ifdef CONFIG_DEBUG_SPINLOCK - BUG_ON(lock->magic != SPINLOCK_MAGIC); - assert_spin_locked(lock); -#endif __asm__ __volatile__( - spin_unlock_string - ); + __raw_spin_lock_string + :"=m" (lock->slock) : : "memory"); } -#endif +#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock) -static inline int _raw_spin_trylock(spinlock_t *lock) +static inline int __raw_spin_trylock(raw_spinlock_t *lock) { char oldval; + __asm__ __volatile__( "xchgb %b0,%1" - :"=q" (oldval), "=m" (lock->lock) + :"=q" (oldval), "=m" (lock->slock) :"0" (0) : "memory"); + return oldval > 0; } -static inline void _raw_spin_lock(spinlock_t *lock) +static inline void __raw_spin_unlock(raw_spinlock_t *lock) { -#ifdef CONFIG_DEBUG_SPINLOCK - if (lock->magic != SPINLOCK_MAGIC) { - printk("eip: %p\n", __builtin_return_address(0)); - BUG(); - } -#endif __asm__ __volatile__( - spin_lock_string - :"=m" (lock->lock) : : "memory"); + __raw_spin_unlock_string + ); } +#define __raw_spin_unlock_wait(lock) \ + do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0) /* * Read-write spinlocks, allowing multiple readers @@ -136,33 +76,7 @@ static inline void _raw_spin_lock(spinlock_t *lock) * can "mix" irq-safe locks - any writer needs to get a * irq-safe write-lock, but readers can get non-irqsafe * read-locks. - */ -typedef struct { - volatile unsigned int lock; -#ifdef CONFIG_DEBUG_SPINLOCK - unsigned magic; -#endif -#ifdef CONFIG_PREEMPT - unsigned int break_lock; -#endif -} rwlock_t; - -#define RWLOCK_MAGIC 0xdeaf1eed - -#ifdef CONFIG_DEBUG_SPINLOCK -#define RWLOCK_MAGIC_INIT , RWLOCK_MAGIC -#else -#define RWLOCK_MAGIC_INIT /* */ -#endif - -#define RW_LOCK_UNLOCKED (rwlock_t) { RW_LOCK_BIAS RWLOCK_MAGIC_INIT } - -#define rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while(0) - -#define read_can_lock(x) ((int)(x)->lock > 0) -#define write_can_lock(x) ((x)->lock == RW_LOCK_BIAS) - -/* + * * On x86, we implement read-write locks as a 32-bit counter * with the high bit (sign) being the "contended" bit. * @@ -170,29 +84,24 @@ typedef struct { * * Changed to use the same technique as rw semaphores. See * semaphore.h for details. -ben + * + * the helpers are in arch/i386/kernel/semaphore.c */ -/* the spinlock helpers are in arch/i386/kernel/semaphore.c */ -static inline void _raw_read_lock(rwlock_t *rw) +#define __raw_read_can_lock(x) ((int)(x)->lock > 0) +#define __raw_write_can_lock(x) ((x)->lock == RW_LOCK_BIAS) + +static inline void __raw_read_lock(raw_rwlock_t *rw) { -#ifdef CONFIG_DEBUG_SPINLOCK - BUG_ON(rw->magic != RWLOCK_MAGIC); -#endif __build_read_lock(rw, "__read_lock_failed"); } -static inline void _raw_write_lock(rwlock_t *rw) +static inline void __raw_write_lock(raw_rwlock_t *rw) { -#ifdef CONFIG_DEBUG_SPINLOCK - BUG_ON(rw->magic != RWLOCK_MAGIC); -#endif __build_write_lock(rw, "__write_lock_failed"); } -#define _raw_read_unlock(rw) asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory") -#define _raw_write_unlock(rw) asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory") - -static inline int _raw_read_trylock(rwlock_t *lock) +static inline int __raw_read_trylock(raw_rwlock_t *lock) { atomic_t *count = (atomic_t *)lock; atomic_dec(count); @@ -202,7 +111,7 @@ static inline int _raw_read_trylock(rwlock_t *lock) return 0; } -static inline int _raw_write_trylock(rwlock_t *lock) +static inline int __raw_write_trylock(raw_rwlock_t *lock) { atomic_t *count = (atomic_t *)lock; if (atomic_sub_and_test(RW_LOCK_BIAS, count)) @@ -211,4 +120,15 @@ static inline int _raw_write_trylock(rwlock_t *lock) return 0; } +static inline void __raw_read_unlock(raw_rwlock_t *rw) +{ + asm volatile("lock ; incl %0" :"=m" (rw->lock) : : "memory"); +} + +static inline void __raw_write_unlock(raw_rwlock_t *rw) +{ + asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0" + : "=m" (rw->lock) : : "memory"); +} + #endif /* __ASM_SPINLOCK_H */ diff --git a/include/asm-x86_64/spinlock_types.h b/include/asm-x86_64/spinlock_types.h new file mode 100644 index 000000000000..59efe849f351 --- /dev/null +++ b/include/asm-x86_64/spinlock_types.h @@ -0,0 +1,20 @@ +#ifndef __ASM_SPINLOCK_TYPES_H +#define __ASM_SPINLOCK_TYPES_H + +#ifndef __LINUX_SPINLOCK_TYPES_H +# error "please don't include this file directly" +#endif + +typedef struct { + volatile unsigned int slock; +} raw_spinlock_t; + +#define __RAW_SPIN_LOCK_UNLOCKED { 1 } + +typedef struct { + volatile unsigned int lock; +} raw_rwlock_t; + +#define __RAW_RW_LOCK_UNLOCKED { RW_LOCK_BIAS } + +#endif -- cgit v1.2.2