// SPDX-License-Identifier: GPL-2.0-only/* * Copyright (C) 2016 Facebook * Copyright (C) 2013-2014 Jens Axboe */ #include <linux/sched.h>#include <linux/random.h>#include <linux/sbitmap.h>#include <linux/seq_file.h> static int init_alloc_hint(struct sbitmap *sb, gfp_t flags){	unsigned depth = sb->depth; 	sb->alloc_hint = alloc_percpu_gfp(unsigned int, flags);	if (!sb->alloc_hint)		return -ENOMEM; 	if (depth && !sb->round_robin) {		int i; 		for_each_possible_cpu(i)			*per_cpu_ptr(sb->alloc_hint, i) = prandom_u32() % depth;	}	return 0;} static inline unsigned update_alloc_hint_before_get(struct sbitmap *sb,						    unsigned int depth){	unsigned hint; 	hint = this_cpu_read(*sb->alloc_hint);	if (unlikely(hint >= depth)) {		hint = depth ? prandom_u32() % depth : 0;		this_cpu_write(*sb->alloc_hint, hint);	} 	return hint;} static inline void update_alloc_hint_after_get(struct sbitmap *sb,					       unsigned int depth,					       unsigned int hint,					       unsigned int nr){	if (nr == -1) {		/* If the map is full, a hint won't do us much good. */		this_cpu_write(*sb->alloc_hint, 0);	} else if (nr == hint || unlikely(sb->round_robin)) {		/* Only update the hint if we used it. */		hint = nr + 1;		if (hint >= depth - 1)			hint = 0;		this_cpu_write(*sb->alloc_hint, hint);	}} /* * See if we have deferred clears that we can batch move */static inline bool sbitmap_deferred_clear(struct sbitmap_word *map){	unsigned long mask; 	if (!READ_ONCE(map->cleared))		return false; 	/*	 * First get a stable cleared mask, setting the old mask to 0.	 */	mask = xchg(&map->cleared, 0); 	/*	 * Now clear the masked bits in our free word	 */	atomic_long_andnot(mask, (atomic_long_t *)&map->word);	BUILD_BUG_ON(sizeof(atomic_long_t) != sizeof(map->word));	return true;} int sbitmap_init_node(struct sbitmap *sb, unsigned int depth, int shift,		      gfp_t flags, int node, bool round_robin,		      bool alloc_hint){	unsigned int bits_per_word;	unsigned int i; 	if (shift < 0)		shift = sbitmap_calculate_shift(depth); 	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);	sb->round_robin = round_robin; 	if (depth == 0) {		sb->map = NULL;		return 0;	} 	if (alloc_hint) {		if (init_alloc_hint(sb, flags))			return -ENOMEM;	} else {		sb->alloc_hint = NULL;	} 	sb->map = kcalloc_node(sb->map_nr, sizeof(*sb->map), flags, node);	if (!sb->map) {		free_percpu(sb->alloc_hint);		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; 	for (i = 0; i < sb->map_nr; i++)		sbitmap_deferred_clear(&sb->map[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){	int nr; 	/* don't wrap if starting from 0 */	wrap = wrap && hint; 	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 (hint && wrap) {				hint = 0;				continue;			}			return -1;		} 		if (!test_and_set_bit_lock(nr, word))			break; 		hint = nr + 1;		if (hint >= depth - 1)			hint = 0;	} 	return nr;} static int sbitmap_find_bit_in_index(struct sbitmap *sb, int index,				     unsigned int alloc_hint){	struct sbitmap_word *map = &sb->map[index];	int nr; 	do {		nr = __sbitmap_get_word(&map->word, map->depth, alloc_hint,					!sb->round_robin);		if (nr != -1)			break;		if (!sbitmap_deferred_clear(map))			break;	} while (1); 	return nr;} static int __sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint){	unsigned int i, index;	int nr = -1; 	index = SB_NR_TO_INDEX(sb, alloc_hint); 	/*	 * Unless we're doing round robin tag allocation, just use the	 * alloc_hint to find the right word index. No point in looping	 * twice in find_next_zero_bit() for that case.	 */	if (sb->round_robin)		alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);	else		alloc_hint = 0; 	for (i = 0; i < sb->map_nr; i++) {		nr = sbitmap_find_bit_in_index(sb, index, alloc_hint);		if (nr != -1) {			nr += index << sb->shift;			break;		} 		/* Jump to next index. */		alloc_hint = 0;		if (++index >= sb->map_nr)			index = 0;	} 	return nr;} int sbitmap_get(struct sbitmap *sb){	int nr;	unsigned int hint, depth; 	if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))		return -1; 	depth = READ_ONCE(sb->depth);	hint = update_alloc_hint_before_get(sb, depth);	nr = __sbitmap_get(sb, hint);	update_alloc_hint_after_get(sb, depth, hint, nr); 	return nr;}EXPORT_SYMBOL_GPL(sbitmap_get); static 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++) {again:		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;		} 		if (sbitmap_deferred_clear(&sb->map[index]))			goto again; 		/* Jump to next index. */		index++;		alloc_hint = index << sb->shift; 		if (index >= sb->map_nr) {			index = 0;			alloc_hint = 0;		}	} 	return nr;} int sbitmap_get_shallow(struct sbitmap *sb, unsigned long shallow_depth){	int nr;	unsigned int hint, depth; 	if (WARN_ON_ONCE(unlikely(!sb->alloc_hint)))		return -1; 	depth = READ_ONCE(sb->depth);	hint = update_alloc_hint_before_get(sb, depth);	nr = __sbitmap_get_shallow(sb, hint, shallow_depth);	update_alloc_hint_after_get(sb, depth, hint, nr); 	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 & ~sb->map[i].cleared)			return true;	}	return false;}EXPORT_SYMBOL_GPL(sbitmap_any_bit_set); static unsigned int __sbitmap_weight(const struct sbitmap *sb, bool set){	unsigned int i, weight = 0; 	for (i = 0; i < sb->map_nr; i++) {		const struct sbitmap_word *word = &sb->map[i]; 		if (set)			weight += bitmap_weight(&word->word, word->depth);		else			weight += bitmap_weight(&word->cleared, word->depth);	}	return weight;} static unsigned int sbitmap_cleared(const struct sbitmap *sb){	return __sbitmap_weight(sb, false);} unsigned int sbitmap_weight(const struct sbitmap *sb){	return __sbitmap_weight(sb, true) - sbitmap_cleared(sb);}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, "cleared=%u\n", sbitmap_cleared(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 long cleared = READ_ONCE(sb->map[i].cleared);		unsigned int word_bits = READ_ONCE(sb->map[i].depth); 		word &= ~cleared; 		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(struct sbitmap_queue *sbq,					unsigned int depth){	unsigned int wake_batch;	unsigned int shallow_depth; 	/*	 * 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,	 * potentially limited by a shallow depth, is enough to wake up all of	 * the queues.	 *	 * Each full word of the bitmap has bits_per_word bits, and there might	 * be a partial word. There are depth / bits_per_word full words and	 * depth % bits_per_word bits left over. In bitwise arithmetic:	 *	 * bits_per_word = 1 << shift	 * depth / bits_per_word = depth >> shift	 * depth % bits_per_word = depth & ((1 << shift) - 1)	 *	 * Each word can be limited to sbq->min_shallow_depth bits.	 */	shallow_depth = min(1U << sbq->sb.shift, sbq->min_shallow_depth);	depth = ((depth >> sbq->sb.shift) * shallow_depth +		 min(depth & ((1U << sbq->sb.shift) - 1), shallow_depth));	wake_batch = clamp_t(unsigned int, depth / SBQ_WAIT_QUEUES, 1,			     SBQ_WAKE_BATCH); 	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,				round_robin, true);	if (ret)		return ret; 	sbq->min_shallow_depth = UINT_MAX;	sbq->wake_batch = sbq_calc_wake_batch(sbq, depth);	atomic_set(&sbq->wake_index, 0);	atomic_set(&sbq->ws_active, 0); 	sbq->ws = kzalloc_node(SBQ_WAIT_QUEUES * sizeof(*sbq->ws), flags, node);	if (!sbq->ws) {		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);	} 	return 0;}EXPORT_SYMBOL_GPL(sbitmap_queue_init_node); static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq,					    unsigned int depth){	unsigned int wake_batch = sbq_calc_wake_batch(sbq, depth);	int i; 	if (sbq->wake_batch != wake_batch) {		WRITE_ONCE(sbq->wake_batch, wake_batch);		/*		 * Pairs with the memory barrier in sbitmap_queue_wake_up()		 * to ensure that the batch size is updated before the wait		 * counts.		 */		smp_mb();		for (i = 0; i < SBQ_WAIT_QUEUES; i++)			atomic_set(&sbq->ws[i].wait_cnt, 1);	}} void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth){	sbitmap_queue_update_wake_batch(sbq, depth);	sbitmap_resize(&sbq->sb, depth);}EXPORT_SYMBOL_GPL(sbitmap_queue_resize); int __sbitmap_queue_get(struct sbitmap_queue *sbq){	return sbitmap_get(&sbq->sb);}EXPORT_SYMBOL_GPL(__sbitmap_queue_get); int __sbitmap_queue_get_shallow(struct sbitmap_queue *sbq,				unsigned int shallow_depth){	WARN_ON_ONCE(shallow_depth < sbq->min_shallow_depth); 	return sbitmap_get_shallow(&sbq->sb, shallow_depth);}EXPORT_SYMBOL_GPL(__sbitmap_queue_get_shallow); 

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