/* * Copyright (C) 2016 Facebook * Copyright (C) 2013-2014 Jens Axboe * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public * License v2 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 for more details. * * You should have received a copy of the GNU General Public License * along with this program.  If not, see <https://www.gnu.org/licenses/>. */ #include <linux/sched.h>#include <linux/random.h>#include <linux/sbitmap.h>#include <linux/seq_file.h> int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,		      gfp_t flags, int node){	unsigned int bits_per_word;	unsigned int i; 	if (shift < 0) {		shift = ilog2(BITS_PER_LONG);		/*		 * If the bitmap is small, shrink the number of bits per word so		 * we spread over a few cachelines, at least. If less than 4		 * bits, just forget about it, it's not going to work optimally		 * anyway.		 */		if (depth >= 4) {			while ((4U << shift) > depth)				shift--;		}	}	bits_per_word = 1U << shift;	if (bits_per_word > BITS_PER_LONG)		return -EINVAL; 	sb->shift = shift;	sb->depth = depth;	sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word); 	if (depth == 0) {		sb->map = NULL;		return 0;	} 	sb->map = kzalloc_node(sb->map_nr * sizeof(*sb->map), flags, node);	if (!sb->map)		return -ENOMEM; 	for (i = 0; i < sb->map_nr; i++) {		sb->map[i].depth = min(depth, bits_per_word);		depth -= sb->map[i].depth;	}	return 0;}EXPORT_SYMBOL_GPL(sbitmap_init_node); void sbitmap_resize(struct sbitmap *sb, unsigned int depth){	unsigned int bits_per_word = 1U << sb->shift;	unsigned int i; 	sb->depth = depth;	sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word); 	for (i = 0; i < sb->map_nr; i++) {		sb->map[i].depth = min(depth, bits_per_word);		depth -= sb->map[i].depth;	}}EXPORT_SYMBOL_GPL(sbitmap_resize); static int __sbitmap_get_word(unsigned long *word, unsigned long depth,			      unsigned int hint, bool wrap){	unsigned int orig_hint = hint;	int nr; 	while (1) {		nr = find_next_zero_bit(word, depth, hint);		if (unlikely(nr >= depth)) {			/*			 * We started with an offset, and we didn't reset the			 * offset to 0 in a failure case, so start from 0 to			 * exhaust the map.			 */			if (orig_hint && hint && wrap) {				hint = orig_hint = 0;				continue;			}			return -1;		} 		if (!test_and_set_bit(nr, word))			break; 		hint = nr + 1;		if (hint >= depth - 1)			hint = 0;	} 	return nr;} int sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint, bool round_robin){	unsigned int i, index;	int nr = -1; 	index = SB_NR_TO_INDEX(sb, alloc_hint); 	for (i = 0; i < sb->map_nr; i++) {		nr = __sbitmap_get_word(&sb->map[index].word,					sb->map[index].depth,					SB_NR_TO_BIT(sb, alloc_hint),					!round_robin);		if (nr != -1) {			nr += index << sb->shift;			break;		} 		/* Jump to next index. */		index++;		alloc_hint = index << sb->shift; 		if (index >= sb->map_nr) {			index = 0;			alloc_hint = 0;		}	} 	return nr;}EXPORT_SYMBOL_GPL(sbitmap_get); int sbitmap_get_shallow(struct sbitmap *sb, unsigned int alloc_hint,			unsigned long shallow_depth){	unsigned int i, index;	int nr = -1; 	index = SB_NR_TO_INDEX(sb, alloc_hint); 	for (i = 0; i < sb->map_nr; i++) {		nr = __sbitmap_get_word(&sb->map[index].word,					min(sb->map[index].depth, shallow_depth),					SB_NR_TO_BIT(sb, alloc_hint), true);		if (nr != -1) {			nr += index << sb->shift;			break;		} 		/* Jump to next index. */		index++;		alloc_hint = index << sb->shift; 		if (index >= sb->map_nr) {			index = 0;			alloc_hint = 0;		}	} 	return nr;}EXPORT_SYMBOL_GPL(sbitmap_get_shallow); bool sbitmap_any_bit_set(const struct sbitmap *sb){	unsigned int i; 	for (i = 0; i < sb->map_nr; i++) {		if (sb->map[i].word)			return true;	}	return false;}EXPORT_SYMBOL_GPL(sbitmap_any_bit_set); bool sbitmap_any_bit_clear(const struct sbitmap *sb){	unsigned int i; 	for (i = 0; i < sb->map_nr; i++) {		const struct sbitmap_word *word = &sb->map[i];		unsigned long ret; 		ret = find_first_zero_bit(&word->word, word->depth);		if (ret < word->depth)			return true;	}	return false;}EXPORT_SYMBOL_GPL(sbitmap_any_bit_clear); unsigned int sbitmap_weight(const struct sbitmap *sb){	unsigned int i, weight = 0; 	for (i = 0; i < sb->map_nr; i++) {		const struct sbitmap_word *word = &sb->map[i]; 		weight += bitmap_weight(&word->word, word->depth);	}	return weight;}EXPORT_SYMBOL_GPL(sbitmap_weight); void sbitmap_show(struct sbitmap *sb, struct seq_file *m){	seq_printf(m, "depth=%u\n", sb->depth);	seq_printf(m, "busy=%u\n", sbitmap_weight(sb));	seq_printf(m, "bits_per_word=%u\n", 1U << sb->shift);	seq_printf(m, "map_nr=%u\n", sb->map_nr);}EXPORT_SYMBOL_GPL(sbitmap_show); static inline void emit_byte(struct seq_file *m, unsigned int offset, u8 byte){	if ((offset & 0xf) == 0) {		if (offset != 0)			seq_putc(m, '\n');		seq_printf(m, "%08x:", offset);	}	if ((offset & 0x1) == 0)		seq_putc(m, ' ');	seq_printf(m, "%02x", byte);} void sbitmap_bitmap_show(struct sbitmap *sb, struct seq_file *m){	u8 byte = 0;	unsigned int byte_bits = 0;	unsigned int offset = 0;	int i; 	for (i = 0; i < sb->map_nr; i++) {		unsigned long word = READ_ONCE(sb->map[i].word);		unsigned int word_bits = READ_ONCE(sb->map[i].depth); 		while (word_bits > 0) {			unsigned int bits = min(8 - byte_bits, word_bits); 			byte |= (word & (BIT(bits) - 1)) << byte_bits;			byte_bits += bits;			if (byte_bits == 8) {				emit_byte(m, offset, byte);				byte = 0;				byte_bits = 0;				offset++;			}			word >>= bits;			word_bits -= bits;		}	}	if (byte_bits) {		emit_byte(m, offset, byte);		offset++;	}	if (offset)		seq_putc(m, '\n');}EXPORT_SYMBOL_GPL(sbitmap_bitmap_show); static unsigned int sbq_calc_wake_batch(unsigned int depth){	unsigned int wake_batch; 	/*	 * For each batch, we wake up one queue. We need to make sure that our	 * batch size is small enough that the full depth of the bitmap is	 * enough to wake up all of the queues.	 */	wake_batch = SBQ_WAKE_BATCH;	if (wake_batch > depth / SBQ_WAIT_QUEUES)		wake_batch = max(1U, depth / SBQ_WAIT_QUEUES); 	return wake_batch;} int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth,			    int shift, bool round_robin, gfp_t flags, int node){	int ret;	int i; 	ret = sbitmap_init_node(&sbq->sb, depth, shift, flags, node);	if (ret)		return ret; 	sbq->alloc_hint = alloc_percpu_gfp(unsigned int, flags);	if (!sbq->alloc_hint) {		sbitmap_free(&sbq->sb);		return -ENOMEM;	} 	if (depth && !round_robin) {		for_each_possible_cpu(i)			*per_cpu_ptr(sbq->alloc_hint, i) = prandom_u32() % depth;	} 	sbq->wake_batch = sbq_calc_wake_batch(depth);	atomic_set(&sbq->wake_index, 0); 	sbq->ws = kzalloc_node(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags, node);	if (!sbq->ws) {		free_percpu(sbq->alloc_hint);		sbitmap_free(&sbq->sb);		return -ENOMEM;	} 	for (i = 0; i < SBQ_WAIT_QUEUES; i++) {		init_waitqueue_head(&sbq->ws[i].wait);		atomic_set(&sbq->ws[i].wait_cnt, sbq->wake_batch);	} 	sbq->round_robin = round_robin;	return 0;}EXPORT_SYMBOL_GPL(sbitmap_queue_init_node); void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth){	unsigned int wake_batch = sbq_calc_wake_batch(depth);	int i; 	if (sbq->wake_batch != wake_batch) {		WRITE_ONCE(sbq->wake_batch, wake_batch);		/*		 * Pairs with the memory barrier in sbq_wake_up() to ensure that		 * the batch size is updated before the wait counts.		 */		smp_mb__before_atomic();		for (i = 0; i < SBQ_WAIT_QUEUES; i++)			atomic_set(&sbq->ws[i].wait_cnt, 1);	}	sbitmap_resize(&sbq->sb, depth);}EXPORT_SYMBOL_GPL(sbitmap_queue_resize); int __sbitmap_queue_get(struct sbitmap_queue *sbq){	unsigned int hint, depth;	int nr; 	hint = this_cpu_read(*sbq->alloc_hint);	depth = READ_ONCE(sbq->sb.depth);	if (unlikely(hint >= depth)) {		hint = depth ? prandom_u32() % depth : 0;		this_cpu_write(*sbq->alloc_hint, hint);	}	nr = sbitmap_get(&sbq->sb, hint, sbq->round_robin); 	if (nr == -1) {		/* If the map is full, a hint won't do us much good. */		this_cpu_write(*sbq->alloc_hint, 0);	} else if (nr == hint || unlikely(sbq->round_robin)) {		/* Only update the hint if we used it. */		hint = nr + 1;		if (hint >= depth - 1)			hint = 0;		this_cpu_write(*sbq->alloc_hint, hint);	} 	return nr;}EXPORT_SYMBOL_GPL(__sbitmap_queue_get); int __sbitmap_queue_get_shallow(struct sbitmap_queue *sbq,				unsigned int shallow_depth){	unsigned int hint, depth;	int nr; 	hint = this_cpu_read(*sbq->alloc_hint);	depth = READ_ONCE(sbq->sb.depth);	if (unlikely(hint >= depth)) {		hint = depth ? prandom_u32() % depth : 0;		this_cpu_write(*sbq->alloc_hint, hint);	}	nr = sbitmap_get_shallow(&sbq->sb, hint, shallow_depth); 	if (nr == -1) {		/* If the map is full, a hint won't do us much good. */		this_cpu_write(*sbq->alloc_hint, 0);	} else if (nr == hint || unlikely(sbq->round_robin)) {		/* Only update the hint if we used it. */		hint = nr + 1;		if (hint >= depth - 1)			hint = 0;		this_cpu_write(*sbq->alloc_hint, hint);	} 	return nr;}EXPORT_SYMBOL_GPL(__sbitmap_queue_get_shallow); static struct sbq_wait_state *sbq_wake_ptr(struct sbitmap_queue *sbq){	int i, wake_index; 	wake_index = atomic_read(&sbq->wake_index);	for (i = 0; i < SBQ_WAIT_QUEUES; i++) {		struct sbq_wait_state *ws = &sbq->ws[wake_index]; 		if (waitqueue_active(&ws->wait)) {			int o = atomic_read(&sbq->wake_index); 			if (wake_index != o)				atomic_cmpxchg(&sbq->wake_index, o, wake_index);			return ws;		} 		wake_index = sbq_index_inc(wake_index);	} 	return NULL;} static void sbq_wake_up(struct sbitmap_queue *sbq){	struct sbq_wait_state *ws;	unsigned int wake_batch;	int wait_cnt; 	/*	 * Pairs with the memory barrier in set_current_state() to ensure the	 * proper ordering of clear_bit()/waitqueue_active() in the waker and	 * test_and_set_bit()/prepare_to_wait()/finish_wait() in the waiter. See	 * the comment on waitqueue_active(). This is __after_atomic because we	 * just did clear_bit() in the caller.	 */	smp_mb__after_atomic(); 	ws = sbq_wake_ptr(sbq);	if (!ws)		return; 	wait_cnt = atomic_dec_return(&ws->wait_cnt);	if (wait_cnt <= 0) {		wake_batch = READ_ONCE(sbq->wake_batch);		/*		 * Pairs with the memory barrier in sbitmap_queue_resize() to		 * ensure that we see the batch size update before the wait		 * count is reset.		 */		smp_mb__before_atomic();		/*		 * If there are concurrent callers to sbq_wake_up(), the last		 * one to decrement the wait count below zero will bump it back		 * up. If there is a concurrent resize, the count reset will		 * either cause the cmpxchg to fail or overwrite after the		 * cmpxchg.		 */		atomic_cmpxchg(&ws->wait_cnt, wait_cnt, wait_cnt + wake_batch);		sbq_index_atomic_inc(&sbq->wake_index);		wake_up(&ws->wait);	}} void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr,			 unsigned int cpu){	sbitmap_clear_bit(&sbq->sb, nr);	sbq_wake_up(sbq);	if (likely(!sbq->round_robin && nr < sbq->sb.depth))		*per_cpu_ptr(sbq->alloc_hint, cpu) = nr;}EXPORT_SYMBOL_GPL(sbitmap_queue_clear); void sbitmap_queue_wake_all(struct sbitmap_queue *sbq){	int i, wake_index; 	/*	 * Pairs with the memory barrier in set_current_state() like in	 * sbq_wake_up().	 */	smp_mb();	wake_index = atomic_read(&sbq->wake_index);	for (i = 0; i < SBQ_WAIT_QUEUES; i++) {		struct sbq_wait_state *ws = &sbq->ws[wake_index]; 		if (waitqueue_active(&ws->wait))			wake_up(&ws->wait); 		wake_index = sbq_index_inc(wake_index);	}}EXPORT_SYMBOL_GPL(sbitmap_queue_wake_all); void sbitmap_queue_show(struct sbitmap_queue *sbq, struct seq_file *m)

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