diff options
Diffstat (limited to 'drivers/staging/lustre/lustre/libcfs/libcfs_lock.c')
| -rw-r--r-- | drivers/staging/lustre/lustre/libcfs/libcfs_lock.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/drivers/staging/lustre/lustre/libcfs/libcfs_lock.c b/drivers/staging/lustre/lustre/libcfs/libcfs_lock.c new file mode 100644 index 000000000000..8d6c4adf2ee6 --- /dev/null +++ b/drivers/staging/lustre/lustre/libcfs/libcfs_lock.c @@ -0,0 +1,192 @@ +/* + * GPL HEADER START + * + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 only, + * as published by the Free Software Foundation. + * + * 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 version 2 for more details (a copy is included + * in the LICENSE file that accompanied this code). + * + * You should have received a copy of the GNU General Public License + * version 2 along with this program; if not, write to the + * Free Software Foundation, Inc., 59 Temple Place - Suite 330, + * Boston, MA 021110-1307, USA + * + * GPL HEADER END + */ +/* Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved. + * Copyright (c) 2012, Intel Corporation. + */ +/* + * This file is part of Lustre, http://www.lustre.org/ + * Lustre is a trademark of Sun Microsystems, Inc. + * + * Author: liang@whamcloud.com + */ + +#ifndef EXPORT_SYMTAB +# define EXPORT_SYMTAB +#endif +#define DEBUG_SUBSYSTEM S_LNET + +#include <linux/libcfs/libcfs.h> + + +/** destroy cpu-partition lock, see libcfs_private.h for more detail */ +void +cfs_percpt_lock_free(struct cfs_percpt_lock *pcl) +{ + LASSERT(pcl->pcl_locks != NULL); + LASSERT(!pcl->pcl_locked); + + cfs_percpt_free(pcl->pcl_locks); + LIBCFS_FREE(pcl, sizeof(*pcl)); +} +EXPORT_SYMBOL(cfs_percpt_lock_free); + +/** + * create cpu-partition lock, see libcfs_private.h for more detail. + * + * cpu-partition lock is designed for large-scale SMP system, so we need to + * reduce cacheline conflict as possible as we can, that's the + * reason we always allocate cacheline-aligned memory block. + */ +struct cfs_percpt_lock * +cfs_percpt_lock_alloc(struct cfs_cpt_table *cptab) +{ + struct cfs_percpt_lock *pcl; + spinlock_t *lock; + int i; + + /* NB: cptab can be NULL, pcl will be for HW CPUs on that case */ + LIBCFS_ALLOC(pcl, sizeof(*pcl)); + if (pcl == NULL) + return NULL; + + pcl->pcl_cptab = cptab; + pcl->pcl_locks = cfs_percpt_alloc(cptab, sizeof(*lock)); + if (pcl->pcl_locks == NULL) { + LIBCFS_FREE(pcl, sizeof(*pcl)); + return NULL; + } + + cfs_percpt_for_each(lock, i, pcl->pcl_locks) + spin_lock_init(lock); + + return pcl; +} +EXPORT_SYMBOL(cfs_percpt_lock_alloc); + +/** + * lock a CPU partition + * + * \a index != CFS_PERCPT_LOCK_EX + * hold private lock indexed by \a index + * + * \a index == CFS_PERCPT_LOCK_EX + * exclusively lock @pcl and nobody can take private lock + */ +void +cfs_percpt_lock(struct cfs_percpt_lock *pcl, int index) +{ + int ncpt = cfs_cpt_number(pcl->pcl_cptab); + int i; + + LASSERT(index >= CFS_PERCPT_LOCK_EX && index < ncpt); + + if (ncpt == 1) { + index = 0; + } else { /* serialize with exclusive lock */ + while (pcl->pcl_locked) + cpu_relax(); + } + + if (likely(index != CFS_PERCPT_LOCK_EX)) { + spin_lock(pcl->pcl_locks[index]); + return; + } + + /* exclusive lock request */ + for (i = 0; i < ncpt; i++) { + spin_lock(pcl->pcl_locks[i]); + if (i == 0) { + LASSERT(!pcl->pcl_locked); + /* nobody should take private lock after this + * so I wouldn't starve for too long time */ + pcl->pcl_locked = 1; + } + } +} +EXPORT_SYMBOL(cfs_percpt_lock); + +/** unlock a CPU partition */ +void +cfs_percpt_unlock(struct cfs_percpt_lock *pcl, int index) +{ + int ncpt = cfs_cpt_number(pcl->pcl_cptab); + int i; + + index = ncpt == 1 ? 0 : index; + + if (likely(index != CFS_PERCPT_LOCK_EX)) { + spin_unlock(pcl->pcl_locks[index]); + return; + } + + for (i = ncpt - 1; i >= 0; i--) { + if (i == 0) { + LASSERT(pcl->pcl_locked); + pcl->pcl_locked = 0; + } + spin_unlock(pcl->pcl_locks[i]); + } +} +EXPORT_SYMBOL(cfs_percpt_unlock); + + +/** free cpu-partition refcount */ +void +cfs_percpt_atomic_free(atomic_t **refs) +{ + cfs_percpt_free(refs); +} +EXPORT_SYMBOL(cfs_percpt_atomic_free); + +/** allocate cpu-partition refcount with initial value @init_val */ +atomic_t ** +cfs_percpt_atomic_alloc(struct cfs_cpt_table *cptab, int init_val) +{ + atomic_t **refs; + atomic_t *ref; + int i; + + refs = cfs_percpt_alloc(cptab, sizeof(*ref)); + if (refs == NULL) + return NULL; + + cfs_percpt_for_each(ref, i, refs) + atomic_set(ref, init_val); + return refs; +} +EXPORT_SYMBOL(cfs_percpt_atomic_alloc); + +/** return sum of cpu-partition refs */ +int +cfs_percpt_atomic_summary(atomic_t **refs) +{ + atomic_t *ref; + int i; + int val = 0; + + cfs_percpt_for_each(ref, i, refs) + val += atomic_read(ref); + + return val; +} +EXPORT_SYMBOL(cfs_percpt_atomic_summary); |