scsi: Remove percpu_ida
With its one user gone, remove the library code. Signed-off-by: Matthew Wilcox <willy@infradead.org> Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Matthew Wilcox
Martin K. Petersen
parent
10e9cbb6b5
commit
693ba15c92
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@ -1,83 +0,0 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __PERCPU_IDA_H__
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#define __PERCPU_IDA_H__
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#include <linux/types.h>
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#include <linux/bitops.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/spinlock_types.h>
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#include <linux/wait.h>
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#include <linux/cpumask.h>
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struct percpu_ida_cpu;
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struct percpu_ida {
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/*
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* number of tags available to be allocated, as passed to
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* percpu_ida_init()
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*/
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unsigned nr_tags;
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unsigned percpu_max_size;
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unsigned percpu_batch_size;
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struct percpu_ida_cpu __percpu *tag_cpu;
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/*
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* Bitmap of cpus that (may) have tags on their percpu freelists:
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* steal_tags() uses this to decide when to steal tags, and which cpus
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* to try stealing from.
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*
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* It's ok for a freelist to be empty when its bit is set - steal_tags()
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* will just keep looking - but the bitmap _must_ be set whenever a
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* percpu freelist does have tags.
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*/
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cpumask_t cpus_have_tags;
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struct {
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spinlock_t lock;
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/*
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* When we go to steal tags from another cpu (see steal_tags()),
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* we want to pick a cpu at random. Cycling through them every
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* time we steal is a bit easier and more or less equivalent:
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*/
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unsigned cpu_last_stolen;
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/* For sleeping on allocation failure */
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wait_queue_head_t wait;
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/*
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* Global freelist - it's a stack where nr_free points to the
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* top
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*/
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unsigned nr_free;
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unsigned *freelist;
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} ____cacheline_aligned_in_smp;
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};
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/*
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* Number of tags we move between the percpu freelist and the global freelist at
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* a time
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*/
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#define IDA_DEFAULT_PCPU_BATCH_MOVE 32U
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/* Max size of percpu freelist, */
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#define IDA_DEFAULT_PCPU_SIZE ((IDA_DEFAULT_PCPU_BATCH_MOVE * 3) / 2)
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int percpu_ida_alloc(struct percpu_ida *pool, int state);
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void percpu_ida_free(struct percpu_ida *pool, unsigned tag);
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void percpu_ida_destroy(struct percpu_ida *pool);
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int __percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags,
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unsigned long max_size, unsigned long batch_size);
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static inline int percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags)
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{
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return __percpu_ida_init(pool, nr_tags, IDA_DEFAULT_PCPU_SIZE,
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IDA_DEFAULT_PCPU_BATCH_MOVE);
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}
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typedef int (*percpu_ida_cb)(unsigned, void *);
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int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
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void *data);
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unsigned percpu_ida_free_tags(struct percpu_ida *pool, int cpu);
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#endif /* __PERCPU_IDA_H__ */
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@ -40,7 +40,7 @@ obj-y += bcd.o div64.o sort.o parser.o debug_locks.o random32.o \
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bust_spinlocks.o kasprintf.o bitmap.o scatterlist.o \
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gcd.o lcm.o list_sort.o uuid.o flex_array.o iov_iter.o clz_ctz.o \
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bsearch.o find_bit.o llist.o memweight.o kfifo.o \
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percpu-refcount.o percpu_ida.o rhashtable.o reciprocal_div.o \
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percpu-refcount.o rhashtable.o reciprocal_div.o \
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once.o refcount.o usercopy.o errseq.o bucket_locks.o
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obj-$(CONFIG_STRING_SELFTEST) += test_string.o
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obj-y += string_helpers.o
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370
lib/percpu_ida.c
370
lib/percpu_ida.c
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@ -1,370 +0,0 @@
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/*
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* Percpu IDA library
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*
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* Copyright (C) 2013 Datera, Inc. Kent Overstreet
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2, or (at
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* your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/mm.h>
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#include <linux/bitmap.h>
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#include <linux/bitops.h>
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#include <linux/bug.h>
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#include <linux/err.h>
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#include <linux/export.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/percpu.h>
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#include <linux/sched/signal.h>
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#include <linux/string.h>
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#include <linux/spinlock.h>
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#include <linux/percpu_ida.h>
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struct percpu_ida_cpu {
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/*
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* Even though this is percpu, we need a lock for tag stealing by remote
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* CPUs:
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*/
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spinlock_t lock;
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/* nr_free/freelist form a stack of free IDs */
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unsigned nr_free;
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unsigned freelist[];
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};
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static inline void move_tags(unsigned *dst, unsigned *dst_nr,
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unsigned *src, unsigned *src_nr,
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unsigned nr)
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{
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*src_nr -= nr;
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memcpy(dst + *dst_nr, src + *src_nr, sizeof(unsigned) * nr);
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*dst_nr += nr;
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}
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/*
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* Try to steal tags from a remote cpu's percpu freelist.
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*
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* We first check how many percpu freelists have tags
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*
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* Then we iterate through the cpus until we find some tags - we don't attempt
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* to find the "best" cpu to steal from, to keep cacheline bouncing to a
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* minimum.
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*/
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static inline void steal_tags(struct percpu_ida *pool,
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struct percpu_ida_cpu *tags)
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{
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unsigned cpus_have_tags, cpu = pool->cpu_last_stolen;
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struct percpu_ida_cpu *remote;
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for (cpus_have_tags = cpumask_weight(&pool->cpus_have_tags);
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cpus_have_tags; cpus_have_tags--) {
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cpu = cpumask_next(cpu, &pool->cpus_have_tags);
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if (cpu >= nr_cpu_ids) {
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cpu = cpumask_first(&pool->cpus_have_tags);
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if (cpu >= nr_cpu_ids)
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BUG();
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}
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pool->cpu_last_stolen = cpu;
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remote = per_cpu_ptr(pool->tag_cpu, cpu);
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cpumask_clear_cpu(cpu, &pool->cpus_have_tags);
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if (remote == tags)
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continue;
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spin_lock(&remote->lock);
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if (remote->nr_free) {
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memcpy(tags->freelist,
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remote->freelist,
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sizeof(unsigned) * remote->nr_free);
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tags->nr_free = remote->nr_free;
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remote->nr_free = 0;
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}
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spin_unlock(&remote->lock);
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if (tags->nr_free)
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break;
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}
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}
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/*
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* Pop up to IDA_PCPU_BATCH_MOVE IDs off the global freelist, and push them onto
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* our percpu freelist:
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*/
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static inline void alloc_global_tags(struct percpu_ida *pool,
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struct percpu_ida_cpu *tags)
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{
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move_tags(tags->freelist, &tags->nr_free,
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pool->freelist, &pool->nr_free,
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min(pool->nr_free, pool->percpu_batch_size));
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}
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/**
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* percpu_ida_alloc - allocate a tag
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* @pool: pool to allocate from
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* @state: task state for prepare_to_wait
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*
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* Returns a tag - an integer in the range [0..nr_tags) (passed to
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* tag_pool_init()), or otherwise -ENOSPC on allocation failure.
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*
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* Safe to be called from interrupt context (assuming it isn't passed
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* TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE, of course).
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*
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* @gfp indicates whether or not to wait until a free id is available (it's not
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* used for internal memory allocations); thus if passed __GFP_RECLAIM we may sleep
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* however long it takes until another thread frees an id (same semantics as a
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* mempool).
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*
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* Will not fail if passed TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE.
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*/
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int percpu_ida_alloc(struct percpu_ida *pool, int state)
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{
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DEFINE_WAIT(wait);
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struct percpu_ida_cpu *tags;
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unsigned long flags;
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int tag = -ENOSPC;
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tags = raw_cpu_ptr(pool->tag_cpu);
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spin_lock_irqsave(&tags->lock, flags);
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/* Fastpath */
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if (likely(tags->nr_free >= 0)) {
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tag = tags->freelist[--tags->nr_free];
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spin_unlock_irqrestore(&tags->lock, flags);
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return tag;
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}
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spin_unlock_irqrestore(&tags->lock, flags);
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while (1) {
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spin_lock_irqsave(&pool->lock, flags);
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tags = this_cpu_ptr(pool->tag_cpu);
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/*
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* prepare_to_wait() must come before steal_tags(), in case
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* percpu_ida_free() on another cpu flips a bit in
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* cpus_have_tags
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*
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* global lock held and irqs disabled, don't need percpu lock
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*/
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if (state != TASK_RUNNING)
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prepare_to_wait(&pool->wait, &wait, state);
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if (!tags->nr_free)
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alloc_global_tags(pool, tags);
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if (!tags->nr_free)
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steal_tags(pool, tags);
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if (tags->nr_free) {
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tag = tags->freelist[--tags->nr_free];
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if (tags->nr_free)
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cpumask_set_cpu(smp_processor_id(),
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&pool->cpus_have_tags);
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}
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spin_unlock_irqrestore(&pool->lock, flags);
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if (tag >= 0 || state == TASK_RUNNING)
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break;
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if (signal_pending_state(state, current)) {
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tag = -ERESTARTSYS;
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break;
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}
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schedule();
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}
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if (state != TASK_RUNNING)
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finish_wait(&pool->wait, &wait);
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return tag;
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}
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EXPORT_SYMBOL_GPL(percpu_ida_alloc);
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/**
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* percpu_ida_free - free a tag
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* @pool: pool @tag was allocated from
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* @tag: a tag previously allocated with percpu_ida_alloc()
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*
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* Safe to be called from interrupt context.
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*/
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void percpu_ida_free(struct percpu_ida *pool, unsigned tag)
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{
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struct percpu_ida_cpu *tags;
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unsigned long flags;
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unsigned nr_free;
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BUG_ON(tag >= pool->nr_tags);
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tags = raw_cpu_ptr(pool->tag_cpu);
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spin_lock_irqsave(&tags->lock, flags);
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tags->freelist[tags->nr_free++] = tag;
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nr_free = tags->nr_free;
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if (nr_free == 1) {
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cpumask_set_cpu(smp_processor_id(),
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&pool->cpus_have_tags);
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wake_up(&pool->wait);
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}
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spin_unlock_irqrestore(&tags->lock, flags);
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if (nr_free == pool->percpu_max_size) {
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spin_lock_irqsave(&pool->lock, flags);
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spin_lock(&tags->lock);
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if (tags->nr_free == pool->percpu_max_size) {
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move_tags(pool->freelist, &pool->nr_free,
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tags->freelist, &tags->nr_free,
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pool->percpu_batch_size);
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wake_up(&pool->wait);
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}
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spin_unlock(&tags->lock);
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spin_unlock_irqrestore(&pool->lock, flags);
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}
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}
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EXPORT_SYMBOL_GPL(percpu_ida_free);
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/**
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* percpu_ida_destroy - release a tag pool's resources
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* @pool: pool to free
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*
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* Frees the resources allocated by percpu_ida_init().
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*/
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void percpu_ida_destroy(struct percpu_ida *pool)
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{
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free_percpu(pool->tag_cpu);
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free_pages((unsigned long) pool->freelist,
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get_order(pool->nr_tags * sizeof(unsigned)));
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}
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EXPORT_SYMBOL_GPL(percpu_ida_destroy);
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/**
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* percpu_ida_init - initialize a percpu tag pool
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* @pool: pool to initialize
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* @nr_tags: number of tags that will be available for allocation
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*
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* Initializes @pool so that it can be used to allocate tags - integers in the
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* range [0, nr_tags). Typically, they'll be used by driver code to refer to a
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* preallocated array of tag structures.
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*
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* Allocation is percpu, but sharding is limited by nr_tags - for best
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* performance, the workload should not span more cpus than nr_tags / 128.
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*/
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int __percpu_ida_init(struct percpu_ida *pool, unsigned long nr_tags,
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unsigned long max_size, unsigned long batch_size)
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{
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unsigned i, cpu, order;
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memset(pool, 0, sizeof(*pool));
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init_waitqueue_head(&pool->wait);
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spin_lock_init(&pool->lock);
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pool->nr_tags = nr_tags;
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pool->percpu_max_size = max_size;
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pool->percpu_batch_size = batch_size;
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/* Guard against overflow */
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if (nr_tags > (unsigned) INT_MAX + 1) {
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pr_err("percpu_ida_init(): nr_tags too large\n");
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return -EINVAL;
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}
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order = get_order(nr_tags * sizeof(unsigned));
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pool->freelist = (void *) __get_free_pages(GFP_KERNEL, order);
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if (!pool->freelist)
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return -ENOMEM;
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for (i = 0; i < nr_tags; i++)
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pool->freelist[i] = i;
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pool->nr_free = nr_tags;
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pool->tag_cpu = __alloc_percpu(sizeof(struct percpu_ida_cpu) +
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pool->percpu_max_size * sizeof(unsigned),
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sizeof(unsigned));
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if (!pool->tag_cpu)
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goto err;
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for_each_possible_cpu(cpu)
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spin_lock_init(&per_cpu_ptr(pool->tag_cpu, cpu)->lock);
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return 0;
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err:
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percpu_ida_destroy(pool);
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return -ENOMEM;
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}
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EXPORT_SYMBOL_GPL(__percpu_ida_init);
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/**
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* percpu_ida_for_each_free - iterate free ids of a pool
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* @pool: pool to iterate
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* @fn: interate callback function
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* @data: parameter for @fn
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*
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* Note, this doesn't guarantee to iterate all free ids restrictly. Some free
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* ids might be missed, some might be iterated duplicated, and some might
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* be iterated and not free soon.
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*/
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int percpu_ida_for_each_free(struct percpu_ida *pool, percpu_ida_cb fn,
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void *data)
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{
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unsigned long flags;
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struct percpu_ida_cpu *remote;
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unsigned cpu, i, err = 0;
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for_each_possible_cpu(cpu) {
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remote = per_cpu_ptr(pool->tag_cpu, cpu);
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spin_lock_irqsave(&remote->lock, flags);
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for (i = 0; i < remote->nr_free; i++) {
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err = fn(remote->freelist[i], data);
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if (err)
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break;
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}
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spin_unlock_irqrestore(&remote->lock, flags);
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if (err)
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goto out;
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}
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spin_lock_irqsave(&pool->lock, flags);
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for (i = 0; i < pool->nr_free; i++) {
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err = fn(pool->freelist[i], data);
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if (err)
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break;
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}
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spin_unlock_irqrestore(&pool->lock, flags);
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out:
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return err;
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}
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EXPORT_SYMBOL_GPL(percpu_ida_for_each_free);
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/**
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* percpu_ida_free_tags - return free tags number of a specific cpu or global pool
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* @pool: pool related
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* @cpu: specific cpu or global pool if @cpu == nr_cpu_ids
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*
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* Note: this just returns a snapshot of free tags number.
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*/
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unsigned percpu_ida_free_tags(struct percpu_ida *pool, int cpu)
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{
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struct percpu_ida_cpu *remote;
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if (cpu == nr_cpu_ids)
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return pool->nr_free;
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remote = per_cpu_ptr(pool->tag_cpu, cpu);
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return remote->nr_free;
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}
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EXPORT_SYMBOL_GPL(percpu_ida_free_tags);
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