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// SPDX-License-Identifier: GPL-2.0
/*
* 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).
*
* GPL HEADER END
*/
/* Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2015 Intel Corporation.
*/
/*
* This file is part of Lustre, http://www.lustre.org/
* Lustre is a trademark of Sun Microsystems, Inc.
*
* Author: liang@whamcloud.com
*/
#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);
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_create(struct cfs_cpt_table *cptab,
struct lock_class_key *keys)
{
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)
return NULL;
pcl->pcl_cptab = cptab;
pcl->pcl_locks = cfs_percpt_alloc(cptab, sizeof(*lock));
if (!pcl->pcl_locks) {
LIBCFS_FREE(pcl, sizeof(*pcl));
return NULL;
}
if (!keys)
CWARN("Cannot setup class key for percpt lock, you may see recursive locking warnings which are actually fake.\n");
cfs_percpt_for_each(lock, i, pcl->pcl_locks) {
spin_lock_init(lock);
if (keys)
lockdep_set_class(lock, &keys[i]);
}
return pcl;
}
EXPORT_SYMBOL(cfs_percpt_lock_create);
/**
* 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)
__acquires(pcl->pcl_locks)
{
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) {
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)
__releases(pcl->pcl_locks)
{
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) {
LASSERT(pcl->pcl_locked);
pcl->pcl_locked = 0;
}
spin_unlock(pcl->pcl_locks[i]);
}
}
EXPORT_SYMBOL(cfs_percpt_unlock);
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