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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#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) = get_random_u32_below(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 ? get_random_u32_below(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 int depth, unsigned int alloc_hint, bool wrap){ unsigned long mask, word_mask;
guard(raw_spinlock_irqsave)(&map->swap_lock);
if (!map->cleared) { if (depth == 0) return false;
word_mask = (~0UL) >> (BITS_PER_LONG - depth); /* * The current behavior is to always retry after moving * ->cleared to word, and we change it to retry in case * of any free bits. To avoid an infinite loop, we need * to take wrap & alloc_hint into account, otherwise a * soft lockup may occur. */ if (!wrap && alloc_hint) word_mask &= ~((1UL << alloc_hint) - 1);
return (READ_ONCE(map->word) & word_mask) != word_mask; }
/* * 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; 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 = kvzalloc_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++) raw_spin_lock_init(&sb->map[i].swap_lock);
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], 0, 0, 0);
sb->depth = depth; sb->map_nr = DIV_ROUND_UP(sb->depth, bits_per_word);}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_word(struct sbitmap_word *map, unsigned int depth, unsigned int alloc_hint, bool wrap){ int nr;
do { nr = __sbitmap_get_word(&map->word, depth, alloc_hint, wrap); if (nr != -1) break; if (!sbitmap_deferred_clear(map, depth, alloc_hint, wrap)) break; } while (1);
return nr;}
static unsigned int __map_depth_with_shallow(const struct sbitmap *sb, int index, unsigned int shallow_depth){ u64 shallow_word_depth; unsigned int word_depth, reminder;
word_depth = __map_depth(sb, index); if (shallow_depth >= sb->depth) return word_depth;
shallow_word_depth = word_depth * shallow_depth; reminder = do_div(shallow_word_depth, sb->depth);
if (reminder >= (index + 1) * word_depth) shallow_word_depth++;
return (unsigned int)shallow_word_depth;}
static int sbitmap_find_bit(struct sbitmap *sb, unsigned int shallow_depth, unsigned int index, unsigned int alloc_hint, bool wrap){ unsigned int i; int nr = -1;
for (i = 0; i < sb->map_nr; i++) { unsigned int depth = __map_depth_with_shallow(sb, index, shallow_depth);
if (depth) nr = sbitmap_find_bit_in_word(&sb->map[index], depth, alloc_hint, wrap); if (nr != -1) { nr += index << sb->shift; break; }
/* Jump to next index. */ alloc_hint = 0; if (++index >= sb->map_nr) index = 0; }
return nr;}
static int __sbitmap_get(struct sbitmap *sb, unsigned int alloc_hint){ unsigned int index;
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;
return sbitmap_find_bit(sb, UINT_MAX, index, alloc_hint, !sb->round_robin);}
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 index;
index = SB_NR_TO_INDEX(sb, alloc_hint); alloc_hint = SB_NR_TO_BIT(sb, alloc_hint);
return sbitmap_find_bit(sb, shallow_depth, index, alloc_hint, true);}
/** * sbitmap_get_shallow() - Try to allocate a free bit from a &struct sbitmap, * limiting the depth used from each word. * @sb: Bitmap to allocate from. * @shallow_depth: The maximum number of bits to allocate from the bitmap. * * This rather specific operation allows for having multiple users with * different allocation limits. E.g., there can be a high-priority class that * uses sbitmap_get() and a low-priority class that uses sbitmap_get_shallow() * with a @shallow_depth of (sb->depth >> 1). Then, the low-priority * class can only allocate half of the total bits in the bitmap, preventing it * from starving out the high-priority class. * * Return: Non-negative allocated bit number if successful, -1 otherwise. */static 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;}
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]; unsigned int word_depth = __map_depth(sb, 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 = __map_depth(sb, i);
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){ return clamp_t(unsigned int, min(depth, sbq->min_shallow_depth) / SBQ_WAIT_QUEUES, 1, SBQ_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); atomic_set(&sbq->completion_cnt, 0); atomic_set(&sbq->wakeup_cnt, 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);
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;
wake_batch = sbq_calc_wake_batch(sbq, depth); if (sbq->wake_batch != wake_batch) WRITE_ONCE(sbq->wake_batch, wake_batch);}
void sbitmap_queue_recalculate_wake_batch(struct sbitmap_queue *sbq, unsigned int users){ unsigned int wake_batch; unsigned int depth = (sbq->sb.depth + users - 1) / users;
wake_batch = clamp_val(depth / SBQ_WAIT_QUEUES, 1, SBQ_WAKE_BATCH);
WRITE_ONCE(sbq->wake_batch, wake_batch);}EXPORT_SYMBOL_GPL(sbitmap_queue_recalculate_wake_batch);
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);
unsigned long __sbitmap_queue_get_batch(struct sbitmap_queue *sbq, int nr_tags, unsigned int *offset){ struct sbitmap *sb = &sbq->sb; unsigned int hint, depth; unsigned long index, nr; int i;
if (unlikely(sb->round_robin)) return 0;
depth = READ_ONCE(sb->depth); hint = update_alloc_hint_before_get(sb, depth);
index = SB_NR_TO_INDEX(sb, hint);
for (i = 0; i < sb->map_nr; i++) { struct sbitmap_word *map = &sb->map[index]; unsigned long get_mask; unsigned int map_depth = __map_depth(sb, index); unsigned long val;
sbitmap_deferred_clear(map, 0, 0, 0); val = READ_ONCE(map->word); if (val == (1UL << (map_depth - 1)) - 1) goto next;
nr = find_first_zero_bit(&val, map_depth); if (nr + nr_tags <= map_depth) { atomic_long_t *ptr = (atomic_long_t *) &map->word;
get_mask = ((1UL << nr_tags) - 1) << nr; while (!atomic_long_try_cmpxchg(ptr, &val, get_mask | val)) ; get_mask = (get_mask & ~val) >> nr; if (get_mask) { *offset = nr + (index << sb->shift); update_alloc_hint_after_get(sb, depth, hint, *offset + nr_tags - 1); return get_mask; } }next: /* Jump to next index. */ if (++index >= sb->map_nr) index = 0; }
return 0;}
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);
void sbitmap_queue_min_shallow_depth(struct sbitmap_queue *sbq, unsigned int min_shallow_depth){ sbq->min_shallow_depth = min_shallow_depth; sbitmap_queue_update_wake_batch(sbq, sbq->sb.depth);}EXPORT_SYMBOL_GPL(sbitmap_queue_min_shallow_depth);
static void __sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr){ int i, wake_index, woken;
if (!atomic_read(&sbq->ws_active)) return;
wake_index = atomic_read(&sbq->wake_index); for (i = 0; i < SBQ_WAIT_QUEUES; i++) { struct sbq_wait_state *ws = &sbq->ws[wake_index];
/* * Advance the index before checking the current queue. * It improves fairness, by ensuring the queue doesn't * need to be fully emptied before trying to wake up * from the next one. */ wake_index = sbq_index_inc(wake_index);
if (waitqueue_active(&ws->wait)) { woken = wake_up_nr(&ws->wait, nr); if (woken == nr) break; nr -= woken; } }
if (wake_index != atomic_read(&sbq->wake_index)) atomic_set(&sbq->wake_index, wake_index);}
void sbitmap_queue_wake_up(struct sbitmap_queue *sbq, int nr){ unsigned int wake_batch = READ_ONCE(sbq->wake_batch); unsigned int wakeups;
if (!atomic_read(&sbq->ws_active)) return;
atomic_add(nr, &sbq->completion_cnt); wakeups = atomic_read(&sbq->wakeup_cnt);
do { if (atomic_read(&sbq->completion_cnt) - wakeups < wake_batch) return; } while (!atomic_try_cmpxchg(&sbq->wakeup_cnt, &wakeups, wakeups + wake_batch));
__sbitmap_queue_wake_up(sbq, wake_batch);}EXPORT_SYMBOL_GPL(sbitmap_queue_wake_up);
static inline void sbitmap_update_cpu_hint(struct sbitmap *sb, int cpu, int tag){ if (likely(!sb->round_robin && tag < sb->depth)) data_race(*per_cpu_ptr(sb->alloc_hint, cpu) = tag);}
void sbitmap_queue_clear_batch(struct sbitmap_queue *sbq, int offset, int *tags, int nr_tags){ struct sbitmap *sb = &sbq->sb; unsigned long *addr = NULL; unsigned long mask = 0; int i;
smp_mb__before_atomic(); for (i = 0; i < nr_tags; i++) { const int tag = tags[i] - offset; unsigned long *this_addr;
/* since we're clearing a batch, skip the deferred map */ this_addr = &sb->map[SB_NR_TO_INDEX(sb, tag)].word; if (!addr) { addr = this_addr; } else if (addr != this_addr) { atomic_long_andnot(mask, (atomic_long_t *) addr); mask = 0; addr = this_addr; } mask |= (1UL << SB_NR_TO_BIT(sb, tag)); }
if (mask) atomic_long_andnot(mask, (atomic_long_t *) addr);
smp_mb__after_atomic(); sbitmap_queue_wake_up(sbq, nr_tags); sbitmap_update_cpu_hint(&sbq->sb, raw_smp_processor_id(), tags[nr_tags - 1] - offset);}
void sbitmap_queue_clear(struct sbitmap_queue *sbq, unsigned int nr, unsigned int cpu){ /* * Once the clear bit is set, the bit may be allocated out. * * Orders READ/WRITE on the associated instance(such as request * of blk_mq) by this bit for avoiding race with re-allocation, * and its pair is the memory barrier implied in __sbitmap_get_word. * * One invariant is that the clear bit has to be zero when the bit * is in use. */ smp_mb__before_atomic(); sbitmap_deferred_clear_bit(&sbq->sb, nr);
/* * Pairs with the memory barrier in set_current_state() to ensure the * proper ordering of clear_bit_unlock()/waitqueue_active() in the waker * and test_and_set_bit_lock()/prepare_to_wait()/finish_wait() in the * waiter. See the comment on waitqueue_active(). */ smp_mb__after_atomic(); sbitmap_queue_wake_up(sbq, 1); sbitmap_update_cpu_hint(&sbq->sb, 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 * sbitmap_queue_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){ bool first; int i;
sbitmap_show(&sbq->sb, m);
seq_puts(m, "alloc_hint={"); first = true; for_each_possible_cpu(i) { if (!first) seq_puts(m, ", "); first = false; seq_printf(m, "%u", *per_cpu_ptr(sbq->sb.alloc_hint, i)); } seq_puts(m, "}\n");
seq_printf(m, "wake_batch=%u\n", sbq->wake_batch); seq_printf(m, "wake_index=%d\n", atomic_read(&sbq->wake_index)); seq_printf(m, "ws_active=%d\n", atomic_read(&sbq->ws_active));
seq_puts(m, "ws={\n"); for (i = 0; i < SBQ_WAIT_QUEUES; i++) { struct sbq_wait_state *ws = &sbq->ws[i]; seq_printf(m, "\t{.wait=%s},\n", waitqueue_active(&ws->wait) ? "active" : "inactive"); } seq_puts(m, "}\n");
seq_printf(m, "round_robin=%d\n", sbq->sb.round_robin); seq_printf(m, "min_shallow_depth=%u\n", sbq->min_shallow_depth);}EXPORT_SYMBOL_GPL(sbitmap_queue_show);
void sbitmap_add_wait_queue(struct sbitmap_queue *sbq, struct sbq_wait_state *ws, struct sbq_wait *sbq_wait){ if (!sbq_wait->sbq) { sbq_wait->sbq = sbq; atomic_inc(&sbq->ws_active); add_wait_queue(&ws->wait, &sbq_wait->wait); }}EXPORT_SYMBOL_GPL(sbitmap_add_wait_queue);
void sbitmap_del_wait_queue(struct sbq_wait *sbq_wait){ list_del_init(&sbq_wait->wait.entry); if (sbq_wait->sbq) { atomic_dec(&sbq_wait->sbq->ws_active); sbq_wait->sbq = NULL; }}EXPORT_SYMBOL_GPL(sbitmap_del_wait_queue);
void sbitmap_prepare_to_wait(struct sbitmap_queue *sbq, struct sbq_wait_state *ws, struct sbq_wait *sbq_wait, int state){ if (!sbq_wait->sbq) { atomic_inc(&sbq->ws_active); sbq_wait->sbq = sbq; } prepare_to_wait_exclusive(&ws->wait, &sbq_wait->wait, state);}EXPORT_SYMBOL_GPL(sbitmap_prepare_to_wait);
void sbitmap_finish_wait(struct sbitmap_queue *sbq, struct sbq_wait_state *ws, struct sbq_wait *sbq_wait){ finish_wait(&ws->wait, &sbq_wait->wait); if (sbq_wait->sbq) { atomic_dec(&sbq->ws_active); sbq_wait->sbq = NULL; }}EXPORT_SYMBOL_GPL(sbitmap_finish_wait);