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 --- arch/parisc/lib/Makefile | 2 - arch/parisc/lib/bitops.c | 4 +- arch/parisc/lib/debuglocks.c | 277 ------------------------------------------- 3 files changed, 2 insertions(+), 281 deletions(-) delete mode 100644 arch/parisc/lib/debuglocks.c (limited to 'arch/parisc/lib') diff --git a/arch/parisc/lib/Makefile b/arch/parisc/lib/Makefile index 7bf70567629..5f2e6904d14 100644 --- a/arch/parisc/lib/Makefile +++ b/arch/parisc/lib/Makefile @@ -5,5 +5,3 @@ lib-y := lusercopy.o bitops.o checksum.o io.o memset.o fixup.o memcpy.o obj-y := iomap.o - -lib-$(CONFIG_SMP) += debuglocks.o diff --git a/arch/parisc/lib/bitops.c b/arch/parisc/lib/bitops.c index 2de182f6fe8..90f400b1028 100644 --- a/arch/parisc/lib/bitops.c +++ b/arch/parisc/lib/bitops.c @@ -13,8 +13,8 @@ #include #ifdef CONFIG_SMP -spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] __lock_aligned = { - [0 ... (ATOMIC_HASH_SIZE-1)] = SPIN_LOCK_UNLOCKED +raw_spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] __lock_aligned = { + [0 ... (ATOMIC_HASH_SIZE-1)] = __RAW_SPIN_LOCK_UNLOCKED }; #endif diff --git a/arch/parisc/lib/debuglocks.c b/arch/parisc/lib/debuglocks.c deleted file mode 100644 index 1b33fe6e5b7..00000000000 --- a/arch/parisc/lib/debuglocks.c +++ /dev/null @@ -1,277 +0,0 @@ -/* - * Debugging versions of SMP locking primitives. - * - * Copyright (C) 2004 Thibaut VARENE - * - * Some code stollen from alpha & sparc64 ;) - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * This program is distributed in the hope that it will be useful, - * but WITHOUT ANY WARRANTY; without even the implied warranty of - * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - * GNU General Public License for more details. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA - * - * We use pdc_printf() throughout the file for all output messages, to avoid - * losing messages because of disabled interrupts. Since we're using these - * messages for debugging purposes, it makes sense not to send them to the - * linux console. - */ - - -#include -#include -#include -#include -#include /* in_interrupt() */ -#include -#include /* in_interrupt() */ -#include - -#undef INIT_STUCK -#define INIT_STUCK 1L << 30 - -#ifdef CONFIG_DEBUG_SPINLOCK - - -void _dbg_spin_lock(spinlock_t * lock, const char *base_file, int line_no) -{ - volatile unsigned int *a; - long stuck = INIT_STUCK; - void *inline_pc = __builtin_return_address(0); - unsigned long started = jiffies; - int printed = 0; - int cpu = smp_processor_id(); - -try_again: - - /* Do the actual locking */ - /* ggg: we can't get stuck on the outter loop? - * T-Bone: We can hit the outer loop - * alot if multiple CPUs are constantly racing for a lock - * and the backplane is NOT fair about which CPU sees - * the update first. But it won't hang since every failed - * attempt will drop us back into the inner loop and - * decrement `stuck'. - * K-class and some of the others are NOT fair in the HW - * implementation so we could see false positives. - * But fixing the lock contention is easier than - * fixing the HW to be fair. - * __ldcw() returns 1 if we get the lock; otherwise we - * spin until the value of the lock changes, or we time out. - */ - mb(); - a = __ldcw_align(lock); - while (stuck && (__ldcw(a) == 0)) - while ((*a == 0) && --stuck); - mb(); - - if (unlikely(stuck <= 0)) { - pdc_printf( - "%s:%d: spin_lock(%s/%p) stuck in %s at %p(%d)" - " owned by %s:%d in %s at %p(%d)\n", - base_file, line_no, lock->module, lock, - current->comm, inline_pc, cpu, - lock->bfile, lock->bline, lock->task->comm, - lock->previous, lock->oncpu); - stuck = INIT_STUCK; - printed = 1; - goto try_again; - } - - /* Exiting. Got the lock. */ - lock->oncpu = cpu; - lock->previous = inline_pc; - lock->task = current; - lock->bfile = (char *)base_file; - lock->bline = line_no; - - if (unlikely(printed)) { - pdc_printf( - "%s:%d: spin_lock grabbed in %s at %p(%d) %ld ticks\n", - base_file, line_no, current->comm, inline_pc, - cpu, jiffies - started); - } -} - -void _dbg_spin_unlock(spinlock_t * lock, const char *base_file, int line_no) -{ - CHECK_LOCK(lock); - volatile unsigned int *a; - mb(); - a = __ldcw_align(lock); - if (unlikely((*a != 0) && lock->babble)) { - lock->babble--; - pdc_printf( - "%s:%d: spin_unlock(%s:%p) not locked\n", - base_file, line_no, lock->module, lock); - } - *a = 1; - mb(); -} - -int _dbg_spin_trylock(spinlock_t * lock, const char *base_file, int line_no) -{ - int ret; - volatile unsigned int *a; - mb(); - a = __ldcw_align(lock); - ret = (__ldcw(a) != 0); - mb(); - if (ret) { - lock->oncpu = smp_processor_id(); - lock->previous = __builtin_return_address(0); - lock->task = current; - } else { - lock->bfile = (char *)base_file; - lock->bline = line_no; - } - return ret; -} - -#endif /* CONFIG_DEBUG_SPINLOCK */ - -#ifdef CONFIG_DEBUG_RWLOCK - -/* Interrupts trouble detailed explanation, thx Grant: - * - * o writer (wants to modify data) attempts to acquire the rwlock - * o He gets the write lock. - * o Interupts are still enabled, we take an interrupt with the - * write still holding the lock. - * o interrupt handler tries to acquire the rwlock for read. - * o deadlock since the writer can't release it at this point. - * - * In general, any use of spinlocks that competes between "base" - * level and interrupt level code will risk deadlock. Interrupts - * need to be disabled in the base level routines to avoid it. - * Or more precisely, only the IRQ the base level routine - * is competing with for the lock. But it's more efficient/faster - * to just disable all interrupts on that CPU to guarantee - * once it gets the lock it can release it quickly too. - */ - -void _dbg_write_lock(rwlock_t *rw, const char *bfile, int bline) -{ - void *inline_pc = __builtin_return_address(0); - unsigned long started = jiffies; - long stuck = INIT_STUCK; - int printed = 0; - int cpu = smp_processor_id(); - - if(unlikely(in_interrupt())) { /* acquiring write lock in interrupt context, bad idea */ - pdc_printf("write_lock caller: %s:%d, IRQs enabled,\n", bfile, bline); - BUG(); - } - - /* Note: if interrupts are disabled (which is most likely), the printk - will never show on the console. We might need a polling method to flush - the dmesg buffer anyhow. */ - -retry: - _raw_spin_lock(&rw->lock); - - if(rw->counter != 0) { - /* this basically never happens */ - _raw_spin_unlock(&rw->lock); - - stuck--; - if ((unlikely(stuck <= 0)) && (rw->counter < 0)) { - pdc_printf( - "%s:%d: write_lock stuck on writer" - " in %s at %p(%d) %ld ticks\n", - bfile, bline, current->comm, inline_pc, - cpu, jiffies - started); - stuck = INIT_STUCK; - printed = 1; - } - else if (unlikely(stuck <= 0)) { - pdc_printf( - "%s:%d: write_lock stuck on reader" - " in %s at %p(%d) %ld ticks\n", - bfile, bline, current->comm, inline_pc, - cpu, jiffies - started); - stuck = INIT_STUCK; - printed = 1; - } - - while(rw->counter != 0); - - goto retry; - } - - /* got it. now leave without unlocking */ - rw->counter = -1; /* remember we are locked */ - - if (unlikely(printed)) { - pdc_printf( - "%s:%d: write_lock grabbed in %s at %p(%d) %ld ticks\n", - bfile, bline, current->comm, inline_pc, - cpu, jiffies - started); - } -} - -int _dbg_write_trylock(rwlock_t *rw, const char *bfile, int bline) -{ -#if 0 - void *inline_pc = __builtin_return_address(0); - int cpu = smp_processor_id(); -#endif - - if(unlikely(in_interrupt())) { /* acquiring write lock in interrupt context, bad idea */ - pdc_printf("write_lock caller: %s:%d, IRQs enabled,\n", bfile, bline); - BUG(); - } - - /* Note: if interrupts are disabled (which is most likely), the printk - will never show on the console. We might need a polling method to flush - the dmesg buffer anyhow. */ - - _raw_spin_lock(&rw->lock); - - if(rw->counter != 0) { - /* this basically never happens */ - _raw_spin_unlock(&rw->lock); - return 0; - } - - /* got it. now leave without unlocking */ - rw->counter = -1; /* remember we are locked */ -#if 0 - pdc_printf("%s:%d: try write_lock grabbed in %s at %p(%d)\n", - bfile, bline, current->comm, inline_pc, cpu); -#endif - return 1; -} - -void _dbg_read_lock(rwlock_t * rw, const char *bfile, int bline) -{ -#if 0 - void *inline_pc = __builtin_return_address(0); - unsigned long started = jiffies; - int cpu = smp_processor_id(); -#endif - unsigned long flags; - - local_irq_save(flags); - _raw_spin_lock(&rw->lock); - - rw->counter++; -#if 0 - pdc_printf( - "%s:%d: read_lock grabbed in %s at %p(%d) %ld ticks\n", - bfile, bline, current->comm, inline_pc, - cpu, jiffies - started); -#endif - _raw_spin_unlock(&rw->lock); - local_irq_restore(flags); -} - -#endif /* CONFIG_DEBUG_RWLOCK */ -- cgit v1.2.3