ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 252 insertions, 0 deletions

diff --git a/drivers/md/bcache/movinggc.c b/drivers/md/bcache/movinggc.c
new file mode 100644
index 000000000..73918e55b
--- /dev/null
+++ b/drivers/md/bcache/movinggc.c
@@ -0,0 +1,252 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Moving/copying garbage collector
+ *
+ * Copyright 2012 Google, Inc.
+ */
+
+#include "bcache.h"
+#include "btree.h"
+#include "debug.h"
+#include "request.h"
+
+#include <trace/events/bcache.h>
+
+struct moving_io {
+	struct closure		cl;
+	struct keybuf_key	*w;
+	struct data_insert_op	op;
+	struct bbio		bio;
+};
+
+static bool moving_pred(struct keybuf *buf, struct bkey *k)
+{
+	struct cache_set *c = container_of(buf, struct cache_set,
+					   moving_gc_keys);
+	unsigned int i;
+
+	for (i = 0; i < KEY_PTRS(k); i++)
+		if (ptr_available(c, k, i) &&
+		    GC_MOVE(PTR_BUCKET(c, k, i)))
+			return true;
+
+	return false;
+}
+
+/* Moving GC - IO loop */
+
+static CLOSURE_CALLBACK(moving_io_destructor)
+{
+	closure_type(io, struct moving_io, cl);
+
+	kfree(io);
+}
+
+static CLOSURE_CALLBACK(write_moving_finish)
+{
+	closure_type(io, struct moving_io, cl);
+	struct bio *bio = &io->bio.bio;
+
+	bio_free_pages(bio);
+
+	if (io->op.replace_collision)
+		trace_bcache_gc_copy_collision(&io->w->key);
+
+	bch_keybuf_del(&io->op.c->moving_gc_keys, io->w);
+
+	up(&io->op.c->moving_in_flight);
+
+	closure_return_with_destructor(cl, moving_io_destructor);
+}
+
+static void read_moving_endio(struct bio *bio)
+{
+	struct bbio *b = container_of(bio, struct bbio, bio);
+	struct moving_io *io = container_of(bio->bi_private,
+					    struct moving_io, cl);
+
+	if (bio->bi_status)
+		io->op.status = bio->bi_status;
+	else if (!KEY_DIRTY(&b->key) &&
+		 ptr_stale(io->op.c, &b->key, 0)) {
+		io->op.status = BLK_STS_IOERR;
+	}
+
+	bch_bbio_endio(io->op.c, bio, bio->bi_status, "reading data to move");
+}
+
+static void moving_init(struct moving_io *io)
+{
+	struct bio *bio = &io->bio.bio;
+
+	bio_init_inline(bio, NULL,
+		 DIV_ROUND_UP(KEY_SIZE(&io->w->key), PAGE_SECTORS), 0);
+	bio_get(bio);
+	bio->bi_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0);
+
+	bio->bi_iter.bi_size	= KEY_SIZE(&io->w->key) << 9;
+	bio->bi_private		= &io->cl;
+	bch_bio_map(bio, NULL);
+}
+
+static CLOSURE_CALLBACK(write_moving)
+{
+	closure_type(io, struct moving_io, cl);
+	struct data_insert_op *op = &io->op;
+
+	if (!op->status) {
+		moving_init(io);
+
+		io->bio.bio.bi_iter.bi_sector = KEY_START(&io->w->key);
+		op->write_prio		= 1;
+		op->bio			= &io->bio.bio;
+
+		op->writeback		= KEY_DIRTY(&io->w->key);
+		op->csum		= KEY_CSUM(&io->w->key);
+
+		bkey_copy(&op->replace_key, &io->w->key);
+		op->replace		= true;
+
+		closure_call(&op->cl, bch_data_insert, NULL, cl);
+	}
+
+	continue_at(cl, write_moving_finish, op->wq);
+}
+
+static CLOSURE_CALLBACK(read_moving_submit)
+{
+	closure_type(io, struct moving_io, cl);
+	struct bio *bio = &io->bio.bio;
+
+	bch_submit_bbio(bio, io->op.c, &io->w->key, 0);
+
+	continue_at(cl, write_moving, io->op.wq);
+}
+
+static void read_moving(struct cache_set *c)
+{
+	struct keybuf_key *w;
+	struct moving_io *io;
+	struct bio *bio;
+	struct closure cl;
+
+	closure_init_stack(&cl);
+
+	/* XXX: if we error, background writeback could stall indefinitely */
+
+	while (!test_bit(CACHE_SET_STOPPING, &c->flags)) {
+		w = bch_keybuf_next_rescan(c, &c->moving_gc_keys,
+					   &MAX_KEY, moving_pred);
+		if (!w)
+			break;
+
+		if (ptr_stale(c, &w->key, 0)) {
+			bch_keybuf_del(&c->moving_gc_keys, w);
+			continue;
+		}
+
+		io = kzalloc(sizeof(*io) + sizeof(struct bio_vec) *
+				DIV_ROUND_UP(KEY_SIZE(&w->key), PAGE_SECTORS),
+				GFP_KERNEL);
+		if (!io)
+			goto err;
+
+		w->private	= io;
+		io->w		= w;
+		io->op.inode	= KEY_INODE(&w->key);
+		io->op.c	= c;
+		io->op.wq	= c->moving_gc_wq;
+
+		moving_init(io);
+		bio = &io->bio.bio;
+
+		bio->bi_opf = REQ_OP_READ;
+		bio->bi_end_io	= read_moving_endio;
+
+		if (bch_bio_alloc_pages(bio, GFP_KERNEL))
+			goto err;
+
+		trace_bcache_gc_copy(&w->key);
+
+		down(&c->moving_in_flight);
+		closure_call(&io->cl, read_moving_submit, NULL, &cl);
+	}
+
+	if (0) {
+err:		if (!IS_ERR_OR_NULL(w->private))
+			kfree(w->private);
+
+		bch_keybuf_del(&c->moving_gc_keys, w);
+	}
+
+	closure_sync(&cl);
+}
+
+static bool bucket_cmp(struct bucket *l, struct bucket *r)
+{
+	return GC_SECTORS_USED(l) < GC_SECTORS_USED(r);
+}
+
+static unsigned int bucket_heap_top(struct cache *ca)
+{
+	struct bucket *b;
+
+	return (b = heap_peek(&ca->heap)) ? GC_SECTORS_USED(b) : 0;
+}
+
+void bch_moving_gc(struct cache_set *c)
+{
+	struct cache *ca = c->cache;
+	struct bucket *b;
+	unsigned long sectors_to_move, reserve_sectors;
+
+	if (!c->copy_gc_enabled)
+		return;
+
+	mutex_lock(&c->bucket_lock);
+
+	sectors_to_move = 0;
+	reserve_sectors = ca->sb.bucket_size *
+			     fifo_used(&ca->free[RESERVE_MOVINGGC]);
+
+	ca->heap.used = 0;
+
+	for_each_bucket(b, ca) {
+		if (GC_MARK(b) == GC_MARK_METADATA ||
+		    !GC_SECTORS_USED(b) ||
+		    GC_SECTORS_USED(b) == ca->sb.bucket_size ||
+		    atomic_read(&b->pin))
+			continue;
+
+		if (!heap_full(&ca->heap)) {
+			sectors_to_move += GC_SECTORS_USED(b);
+			heap_add(&ca->heap, b, bucket_cmp);
+		} else if (bucket_cmp(b, heap_peek(&ca->heap))) {
+			sectors_to_move -= bucket_heap_top(ca);
+			sectors_to_move += GC_SECTORS_USED(b);
+
+			ca->heap.data[0] = b;
+			heap_sift(&ca->heap, 0, bucket_cmp);
+		}
+	}
+
+	while (sectors_to_move > reserve_sectors) {
+		heap_pop(&ca->heap, b, bucket_cmp);
+		sectors_to_move -= GC_SECTORS_USED(b);
+	}
+
+	while (heap_pop(&ca->heap, b, bucket_cmp))
+		SET_GC_MOVE(b, 1);
+
+	mutex_unlock(&c->bucket_lock);
+
+	c->moving_gc_keys.last_scanned = ZERO_KEY;
+
+	read_moving(c);
+}
+
+void bch_moving_init_cache_set(struct cache_set *c)
+{
+	bch_keybuf_init(&c->moving_gc_keys);
+	sema_init(&c->moving_in_flight, 64);
+}