From a9e3760b0838299649c0d57cca44daaf40ba3c33 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 14 Sep 2026 22:12:34 -1000 Subject: sched_ext: Maintain an online cid mask in the scheduler arena Schedulers on the default cid mapping treat [0, nr_online_cids) as the online set and restart on hotplug. Schedulers that install their own mapping with scx_bpf_cid_override() have no way to learn which cids are online: the count no longer identifies members and the CPU-form cpumask is unusable from cid programs. This is an obvious hole in the cid API. Add scx_bpf_online_cmask(), a kernel-maintained cmask in the scheduler's arena, allocated alongside the per-CPU scratch masks and populated after the cid mapping is finalized and before ops.init(), for child schedulers too. The pointer stays valid through ops.exit() with no reference to take. It is the arena offset as a void pointer, the same form struct_ops arena arguments arrive in. The verifier types the void return as a scalar for the program's arena cast. The mask follows the SCX hotplug notifications: seeded from cpu_active_mask and updated before ops.cid_online/offline() runs, so it lags cpu_online_mask only inside a hotplug transition. Updates walk the scheduler list under the lock that also serializes unlinking. Reads are live, not atomic snapshots. Root initialization excludes hotplug. v2: Reworded the getter kerneldoc (Andrea Righi). Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi --- drivers/md/bcache/debug.c | 262 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 262 insertions(+) create mode 100644 drivers/md/bcache/debug.c (limited to 'drivers/md/bcache/debug.c') diff --git a/drivers/md/bcache/debug.c b/drivers/md/bcache/debug.c new file mode 100644 index 000000000..2691a5da3 --- /dev/null +++ b/drivers/md/bcache/debug.c @@ -0,0 +1,262 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Assorted bcache debug code + * + * Copyright 2010, 2011 Kent Overstreet + * Copyright 2012 Google, Inc. + */ + +#include "bcache.h" +#include "btree.h" +#include "debug.h" +#include "extents.h" + +#include +#include +#include +#include +#include + +struct dentry *bcache_debug; + +#ifdef CONFIG_BCACHE_DEBUG + +#define for_each_written_bset(b, start, i) \ + for (i = (start); \ + (void *) i < (void *) (start) + (KEY_SIZE(&b->key) << 9) &&\ + i->seq == (start)->seq; \ + i = (void *) i + set_blocks(i, block_bytes(b->c->cache)) * \ + block_bytes(b->c->cache)) + +void bch_btree_verify(struct btree *b) +{ + struct btree *v = b->c->verify_data; + struct bset *ondisk, *sorted, *inmemory; + struct bio *bio; + + if (!b->c->verify || !b->c->verify_ondisk) + return; + + down(&b->io_mutex); + mutex_lock(&b->c->verify_lock); + + ondisk = b->c->verify_ondisk; + sorted = b->c->verify_data->keys.set->data; + inmemory = b->keys.set->data; + + bkey_copy(&v->key, &b->key); + v->written = 0; + v->level = b->level; + v->keys.ops = b->keys.ops; + + bio = bch_bbio_alloc(b->c); + bio_set_dev(bio, b->c->cache->bdev); + bio->bi_iter.bi_sector = PTR_OFFSET(&b->key, 0); + bio->bi_iter.bi_size = KEY_SIZE(&v->key) << 9; + bio->bi_opf = REQ_OP_READ | REQ_META; + bch_bio_map(bio, sorted); + + submit_bio_wait(bio); + bch_bbio_free(bio, b->c); + + memcpy(ondisk, sorted, KEY_SIZE(&v->key) << 9); + + bch_btree_node_read_done(v); + sorted = v->keys.set->data; + + if (inmemory->keys != sorted->keys || + memcmp(inmemory->start, + sorted->start, + (void *) bset_bkey_last(inmemory) - + (void *) inmemory->start)) { + struct bset *i; + unsigned int j; + + console_lock(); + + pr_err("*** in memory:\n"); + bch_dump_bset(&b->keys, inmemory, 0); + + pr_err("*** read back in:\n"); + bch_dump_bset(&v->keys, sorted, 0); + + for_each_written_bset(b, ondisk, i) { + unsigned int block = ((void *) i - (void *) ondisk) / + block_bytes(b->c->cache); + + pr_err("*** on disk block %u:\n", block); + bch_dump_bset(&b->keys, i, block); + } + + pr_err("*** block %zu not written\n", + ((void *) i - (void *) ondisk) / block_bytes(b->c->cache)); + + for (j = 0; j < inmemory->keys; j++) + if (inmemory->d[j] != sorted->d[j]) + break; + + pr_err("b->written %u\n", b->written); + + console_unlock(); + panic("verify failed at %u\n", j); + } + + mutex_unlock(&b->c->verify_lock); + up(&b->io_mutex); +} + +void bch_data_verify(struct cached_dev *dc, struct bio *bio) +{ + unsigned int nr_segs = bio_segments(bio); + struct bio *check; + struct bio_vec bv, cbv; + struct bvec_iter iter, citer = { 0 }; + + check = bio_kmalloc(nr_segs, GFP_NOIO); + if (!check) + return; + bio_init_inline(check, bio->bi_bdev, nr_segs, REQ_OP_READ); + check->bi_iter.bi_sector = bio->bi_iter.bi_sector; + check->bi_iter.bi_size = bio->bi_iter.bi_size; + + bch_bio_map(check, NULL); + if (bch_bio_alloc_pages(check, GFP_NOIO)) + goto out_put; + + submit_bio_wait(check); + + citer.bi_size = UINT_MAX; + bio_for_each_segment(bv, bio, iter) { + void *p1 = bvec_kmap_local(&bv); + void *p2; + + cbv = bio_iter_iovec(check, citer); + p2 = bvec_kmap_local(&cbv); + + cache_set_err_on(memcmp(p1, p2, bv.bv_len), + dc->disk.c, + "verify failed at dev %pg sector %llu", + dc->bdev, + (uint64_t) bio->bi_iter.bi_sector); + + kunmap_local(p2); + kunmap_local(p1); + bio_advance_iter(check, &citer, bv.bv_len); + } + + bio_free_pages(check); +out_put: + bio_uninit(check); + kfree(check); +} + +#endif + +#ifdef CONFIG_DEBUG_FS + +/* XXX: cache set refcounting */ + +struct dump_iterator { + char buf[PAGE_SIZE]; + size_t bytes; + struct cache_set *c; + struct keybuf keys; +}; + +static bool dump_pred(struct keybuf *buf, struct bkey *k) +{ + return true; +} + +static ssize_t bch_dump_read(struct file *file, char __user *buf, + size_t size, loff_t *ppos) +{ + struct dump_iterator *i = file->private_data; + ssize_t ret = 0; + char kbuf[80]; + + while (size) { + struct keybuf_key *w; + unsigned int bytes = min(i->bytes, size); + + if (copy_to_user(buf, i->buf, bytes)) + return -EFAULT; + + ret += bytes; + buf += bytes; + size -= bytes; + i->bytes -= bytes; + memmove(i->buf, i->buf + bytes, i->bytes); + + if (i->bytes) + break; + + w = bch_keybuf_next_rescan(i->c, &i->keys, &MAX_KEY, dump_pred); + if (!w) + break; + + bch_extent_to_text(kbuf, sizeof(kbuf), &w->key); + i->bytes = snprintf(i->buf, PAGE_SIZE, "%s\n", kbuf); + bch_keybuf_del(&i->keys, w); + } + + return ret; +} + +static int bch_dump_open(struct inode *inode, struct file *file) +{ + struct cache_set *c = inode->i_private; + struct dump_iterator *i; + + i = kzalloc_obj(struct dump_iterator); + if (!i) + return -ENOMEM; + + file->private_data = i; + i->c = c; + bch_keybuf_init(&i->keys); + i->keys.last_scanned = KEY(0, 0, 0); + + return 0; +} + +static int bch_dump_release(struct inode *inode, struct file *file) +{ + kfree(file->private_data); + return 0; +} + +static const struct file_operations cache_set_debug_ops = { + .owner = THIS_MODULE, + .open = bch_dump_open, + .read = bch_dump_read, + .release = bch_dump_release +}; + +void bch_debug_init_cache_set(struct cache_set *c) +{ + if (!IS_ERR_OR_NULL(bcache_debug)) { + char name[50]; + + snprintf(name, 50, "bcache-%pU", c->set_uuid); + c->debug = debugfs_create_file(name, 0400, bcache_debug, c, + &cache_set_debug_ops); + } +} + +#endif + +void bch_debug_exit(void) +{ + debugfs_remove_recursive(bcache_debug); +} + +void __init bch_debug_init(void) +{ + /* + * it is unnecessary to check return value of + * debugfs_create_file(), we should not care + * about this. + */ + bcache_debug = debugfs_create_dir("bcache", NULL); +} -- cgit v1.3.1