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Diffstat (limited to 'lib/sbitmap.c')
-rw-r--r--lib/sbitmap.c139
1 files changed, 131 insertions, 8 deletions
diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 2cecf05c82fd..55e11c4b2f3b 100644
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -17,6 +17,7 @@
#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)
@@ -180,6 +181,62 @@ unsigned int sbitmap_weight(const struct sbitmap *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, "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;
@@ -239,7 +296,19 @@ EXPORT_SYMBOL_GPL(sbitmap_queue_init_node);
void sbitmap_queue_resize(struct sbitmap_queue *sbq, unsigned int depth)
{
- sbq->wake_batch = sbq_calc_wake_batch(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);
@@ -297,20 +366,39 @@ static struct sbq_wait_state *sbq_wake_ptr(struct sbitmap_queue *sbq)
static void sbq_wake_up(struct sbitmap_queue *sbq)
{
struct sbq_wait_state *ws;
+ unsigned int wake_batch;
int wait_cnt;
- /* Ensure that the wait list checks occur after clear_bit(). */
- smp_mb();
+ /*
+ * 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 (unlikely(wait_cnt < 0))
- wait_cnt = atomic_inc_return(&ws->wait_cnt);
- if (wait_cnt == 0) {
- atomic_add(sbq->wake_batch, &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);
}
@@ -331,7 +419,8 @@ void sbitmap_queue_wake_all(struct sbitmap_queue *sbq)
int i, wake_index;
/*
- * Make sure all changes prior to this are visible from other CPUs.
+ * Pairs with the memory barrier in set_current_state() like in
+ * sbq_wake_up().
*/
smp_mb();
wake_index = atomic_read(&sbq->wake_index);
@@ -345,3 +434,37 @@ void sbitmap_queue_wake_all(struct sbitmap_queue *sbq)
}
}
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->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_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_cnt=%d, .wait=%s},\n",
+ atomic_read(&ws->wait_cnt),
+ waitqueue_active(&ws->wait) ? "active" : "inactive");
+ }
+ seq_puts(m, "}\n");
+
+ seq_printf(m, "round_robin=%d\n", sbq->round_robin);
+}
+EXPORT_SYMBOL_GPL(sbitmap_queue_show);