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, 281 insertions, 0 deletions

diff --git a/drivers/md/persistent-data/dm-space-map-disk.c b/drivers/md/persistent-data/dm-space-map-disk.c
new file mode 100644
index 000000000..27c0be9c5
--- /dev/null
+++ b/drivers/md/persistent-data/dm-space-map-disk.c
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2011 Red Hat, Inc.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-space-map-common.h"
+#include "dm-space-map-disk.h"
+#include "dm-space-map.h"
+#include "dm-transaction-manager.h"
+
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include <linux/device-mapper.h>
+
+#define DM_MSG_PREFIX "space map disk"
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Space map interface.
+ */
+struct sm_disk {
+	struct dm_space_map sm;
+
+	struct ll_disk ll;
+	struct ll_disk old_ll;
+
+	dm_block_t begin;
+	dm_block_t nr_allocated_this_transaction;
+};
+
+static void sm_disk_destroy(struct dm_space_map *sm)
+{
+	struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+	kfree(smd);
+}
+
+static int sm_disk_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
+{
+	struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+	return sm_ll_extend(&smd->ll, extra_blocks);
+}
+
+static int sm_disk_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
+{
+	struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+	*count = smd->old_ll.nr_blocks;
+
+	return 0;
+}
+
+static int sm_disk_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
+{
+	struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+	*count = (smd->old_ll.nr_blocks - smd->old_ll.nr_allocated) - smd->nr_allocated_this_transaction;
+
+	return 0;
+}
+
+static int sm_disk_get_count(struct dm_space_map *sm, dm_block_t b,
+			     uint32_t *result)
+{
+	struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+	return sm_ll_lookup(&smd->ll, b, result);
+}
+
+static int sm_disk_count_is_more_than_one(struct dm_space_map *sm, dm_block_t b,
+					  int *result)
+{
+	int r;
+	uint32_t count;
+
+	r = sm_disk_get_count(sm, b, &count);
+	if (r)
+		return r;
+
+	*result = count > 1;
+
+	return 0;
+}
+
+static int sm_disk_set_count(struct dm_space_map *sm, dm_block_t b,
+			     uint32_t count)
+{
+	int r;
+	int32_t nr_allocations;
+	struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+	r = sm_ll_insert(&smd->ll, b, count, &nr_allocations);
+	if (!r)
+		smd->nr_allocated_this_transaction += nr_allocations;
+
+	return r;
+}
+
+static int sm_disk_inc_blocks(struct dm_space_map *sm, dm_block_t b, dm_block_t e)
+{
+	int r;
+	int32_t nr_allocations;
+	struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+	r = sm_ll_inc(&smd->ll, b, e, &nr_allocations);
+	if (!r)
+		smd->nr_allocated_this_transaction += nr_allocations;
+
+	return r;
+}
+
+static int sm_disk_dec_blocks(struct dm_space_map *sm, dm_block_t b, dm_block_t e)
+{
+	int r;
+	int32_t nr_allocations;
+	struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+	r = sm_ll_dec(&smd->ll, b, e, &nr_allocations);
+	if (!r)
+		smd->nr_allocated_this_transaction += nr_allocations;
+
+	return r;
+}
+
+static int sm_disk_new_block(struct dm_space_map *sm, dm_block_t *b)
+{
+	int r;
+	int32_t nr_allocations;
+	struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+	/*
+	 * Any block we allocate has to be free in both the old and current ll.
+	 */
+	r = sm_ll_find_common_free_block(&smd->old_ll, &smd->ll, smd->begin, smd->ll.nr_blocks, b);
+	if (r == -ENOSPC)
+		/*
+		 * There's no free block between smd->begin and the end of the metadata device.
+		 * We search before smd->begin in case something has been freed.
+		 */
+		r = sm_ll_find_common_free_block(&smd->old_ll, &smd->ll, 0, smd->begin, b);
+
+	if (r)
+		return r;
+
+	smd->begin = *b + 1;
+	r = sm_ll_inc(&smd->ll, *b, *b + 1, &nr_allocations);
+	if (!r)
+		smd->nr_allocated_this_transaction += nr_allocations;
+
+	return r;
+}
+
+static int sm_disk_commit(struct dm_space_map *sm)
+{
+	int r;
+	struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+
+	r = sm_ll_commit(&smd->ll);
+	if (r)
+		return r;
+
+	memcpy(&smd->old_ll, &smd->ll, sizeof(smd->old_ll));
+	smd->nr_allocated_this_transaction = 0;
+
+	return 0;
+}
+
+static int sm_disk_root_size(struct dm_space_map *sm, size_t *result)
+{
+	*result = sizeof(struct disk_sm_root);
+
+	return 0;
+}
+
+static int sm_disk_copy_root(struct dm_space_map *sm, void *where_le, size_t max)
+{
+	struct sm_disk *smd = container_of(sm, struct sm_disk, sm);
+	struct disk_sm_root root_le;
+
+	root_le.nr_blocks = cpu_to_le64(smd->ll.nr_blocks);
+	root_le.nr_allocated = cpu_to_le64(smd->ll.nr_allocated);
+	root_le.bitmap_root = cpu_to_le64(smd->ll.bitmap_root);
+	root_le.ref_count_root = cpu_to_le64(smd->ll.ref_count_root);
+
+	if (max < sizeof(root_le))
+		return -ENOSPC;
+
+	memcpy(where_le, &root_le, sizeof(root_le));
+
+	return 0;
+}
+
+/*----------------------------------------------------------------*/
+
+static struct dm_space_map ops = {
+	.destroy = sm_disk_destroy,
+	.extend = sm_disk_extend,
+	.get_nr_blocks = sm_disk_get_nr_blocks,
+	.get_nr_free = sm_disk_get_nr_free,
+	.get_count = sm_disk_get_count,
+	.count_is_more_than_one = sm_disk_count_is_more_than_one,
+	.set_count = sm_disk_set_count,
+	.inc_blocks = sm_disk_inc_blocks,
+	.dec_blocks = sm_disk_dec_blocks,
+	.new_block = sm_disk_new_block,
+	.commit = sm_disk_commit,
+	.root_size = sm_disk_root_size,
+	.copy_root = sm_disk_copy_root,
+	.register_threshold_callback = NULL
+};
+
+struct dm_space_map *dm_sm_disk_create(struct dm_transaction_manager *tm,
+				       dm_block_t nr_blocks)
+{
+	int r;
+	struct sm_disk *smd;
+
+	smd = kmalloc_obj(*smd);
+	if (!smd)
+		return ERR_PTR(-ENOMEM);
+
+	smd->begin = 0;
+	smd->nr_allocated_this_transaction = 0;
+	memcpy(&smd->sm, &ops, sizeof(smd->sm));
+
+	r = sm_ll_new_disk(&smd->ll, tm);
+	if (r)
+		goto bad;
+
+	r = sm_ll_extend(&smd->ll, nr_blocks);
+	if (r)
+		goto bad;
+
+	r = sm_disk_commit(&smd->sm);
+	if (r)
+		goto bad;
+
+	return &smd->sm;
+
+bad:
+	kfree(smd);
+	return ERR_PTR(r);
+}
+EXPORT_SYMBOL_GPL(dm_sm_disk_create);
+
+struct dm_space_map *dm_sm_disk_open(struct dm_transaction_manager *tm,
+				     void *root_le, size_t len)
+{
+	int r;
+	struct sm_disk *smd;
+
+	smd = kmalloc_obj(*smd);
+	if (!smd)
+		return ERR_PTR(-ENOMEM);
+
+	smd->begin = 0;
+	smd->nr_allocated_this_transaction = 0;
+	memcpy(&smd->sm, &ops, sizeof(smd->sm));
+
+	r = sm_ll_open_disk(&smd->ll, tm, root_le, len);
+	if (r)
+		goto bad;
+
+	r = sm_disk_commit(&smd->sm);
+	if (r)
+		goto bad;
+
+	return &smd->sm;
+
+bad:
+	kfree(smd);
+	return ERR_PTR(r);
+}
+EXPORT_SYMBOL_GPL(dm_sm_disk_open);
+
+/*----------------------------------------------------------------*/