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, 223 insertions, 0 deletions

diff --git a/fs/btrfs/tests/extent-buffer-tests.c b/fs/btrfs/tests/extent-buffer-tests.c
new file mode 100644
index 000000000..6a43a64ba
--- /dev/null
+++ b/fs/btrfs/tests/extent-buffer-tests.c
@@ -0,0 +1,223 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2013 Fusion IO.  All rights reserved.
+ */
+
+#include <linux/slab.h>
+#include "btrfs-tests.h"
+#include "../ctree.h"
+#include "../extent_io.h"
+#include "../disk-io.h"
+#include "../accessors.h"
+
+static int test_btrfs_split_item(u32 sectorsize, u32 nodesize)
+{
+	struct btrfs_fs_info *fs_info;
+	struct btrfs_path *path = NULL;
+	struct btrfs_root *root = NULL;
+	struct extent_buffer *eb;
+	char *value = "mary had a little lamb";
+	char *split1 = "mary had a little";
+	char *split2 = " lamb";
+	char *split3 = "mary";
+	char *split4 = " had a little";
+	char buf[32];
+	struct btrfs_key key;
+	u32 value_len = strlen(value);
+	int ret = 0;
+
+	test_msg("running btrfs_split_item tests");
+
+	fs_info = btrfs_alloc_dummy_fs_info(nodesize, sectorsize);
+	if (!fs_info) {
+		test_std_err(TEST_ALLOC_FS_INFO);
+		return -ENOMEM;
+	}
+
+	root = btrfs_alloc_dummy_root(fs_info);
+	if (IS_ERR(root)) {
+		test_std_err(TEST_ALLOC_ROOT);
+		ret = PTR_ERR(root);
+		goto out;
+	}
+
+	path = btrfs_alloc_path();
+	if (!path) {
+		test_std_err(TEST_ALLOC_PATH);
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	eb = alloc_dummy_extent_buffer(fs_info, nodesize);
+	path->nodes[0] = eb;
+	if (!eb) {
+		test_std_err(TEST_ALLOC_EXTENT_BUFFER);
+		ret = -ENOMEM;
+		goto out;
+	}
+	path->slots[0] = 0;
+
+	key.objectid = 0;
+	key.type = BTRFS_EXTENT_CSUM_KEY;
+	key.offset = 0;
+
+	/*
+	 * Passing a NULL trans handle is fine here, we have a dummy root eb
+	 * and the tree is a single node (level 0).
+	 */
+	btrfs_setup_item_for_insert(NULL, root, path, &key, value_len);
+	write_extent_buffer(eb, value, btrfs_item_ptr_offset(eb, 0),
+			    value_len);
+
+	key.offset = 3;
+
+	/*
+	 * Passing NULL trans here should be safe because we have plenty of
+	 * space in this leaf to split the item without having to split the
+	 * leaf.
+	 */
+	ret = btrfs_split_item(NULL, root, path, &key, 17);
+	if (ret) {
+		test_err("split item failed %d", ret);
+		goto out;
+	}
+
+	/*
+	 * Read the first slot, it should have the original key and contain only
+	 * 'mary had a little'
+	 */
+	btrfs_item_key_to_cpu(eb, &key, 0);
+	if (key.objectid != 0 || key.type != BTRFS_EXTENT_CSUM_KEY ||
+	    key.offset != 0) {
+		test_err("invalid key at slot 0");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (btrfs_item_size(eb, 0) != strlen(split1)) {
+		test_err("invalid len in the first split");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	read_extent_buffer(eb, buf, btrfs_item_ptr_offset(eb, 0),
+			   strlen(split1));
+	if (memcmp(buf, split1, strlen(split1))) {
+		test_err(
+"data in the buffer doesn't match what it should in the first split have='%.*s' want '%s'",
+			 (int)strlen(split1), buf, split1);
+		ret = -EINVAL;
+		goto out;
+	}
+
+	btrfs_item_key_to_cpu(eb, &key, 1);
+	if (key.objectid != 0 || key.type != BTRFS_EXTENT_CSUM_KEY ||
+	    key.offset != 3) {
+		test_err("invalid key at slot 1");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (btrfs_item_size(eb, 1) != strlen(split2)) {
+		test_err("invalid len in the second split");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	read_extent_buffer(eb, buf, btrfs_item_ptr_offset(eb, 1),
+			   strlen(split2));
+	if (memcmp(buf, split2, strlen(split2))) {
+		test_err(
+	"data in the buffer doesn't match what it should in the second split");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	key.offset = 1;
+	/* Do it again so we test memmoving the other items in the leaf */
+	ret = btrfs_split_item(NULL, root, path, &key, 4);
+	if (ret) {
+		test_err("second split item failed %d", ret);
+		goto out;
+	}
+
+	btrfs_item_key_to_cpu(eb, &key, 0);
+	if (key.objectid != 0 || key.type != BTRFS_EXTENT_CSUM_KEY ||
+	    key.offset != 0) {
+		test_err("invalid key at slot 0");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (btrfs_item_size(eb, 0) != strlen(split3)) {
+		test_err("invalid len in the first split");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	read_extent_buffer(eb, buf, btrfs_item_ptr_offset(eb, 0),
+			   strlen(split3));
+	if (memcmp(buf, split3, strlen(split3))) {
+		test_err(
+	"data in the buffer doesn't match what it should in the third split");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	btrfs_item_key_to_cpu(eb, &key, 1);
+	if (key.objectid != 0 || key.type != BTRFS_EXTENT_CSUM_KEY ||
+	    key.offset != 1) {
+		test_err("invalid key at slot 1");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (btrfs_item_size(eb, 1) != strlen(split4)) {
+		test_err("invalid len in the second split");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	read_extent_buffer(eb, buf, btrfs_item_ptr_offset(eb, 1),
+			   strlen(split4));
+	if (memcmp(buf, split4, strlen(split4))) {
+		test_err(
+	"data in the buffer doesn't match what it should in the fourth split");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	btrfs_item_key_to_cpu(eb, &key, 2);
+	if (key.objectid != 0 || key.type != BTRFS_EXTENT_CSUM_KEY ||
+	    key.offset != 3) {
+		test_err("invalid key at slot 2");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (btrfs_item_size(eb, 2) != strlen(split2)) {
+		test_err("invalid len in the second split");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	read_extent_buffer(eb, buf, btrfs_item_ptr_offset(eb, 2),
+			   strlen(split2));
+	if (memcmp(buf, split2, strlen(split2))) {
+		test_err(
+	"data in the buffer doesn't match what it should in the last chunk");
+		ret = -EINVAL;
+		goto out;
+	}
+out:
+	btrfs_free_path(path);
+	btrfs_free_dummy_root(root);
+	btrfs_free_dummy_fs_info(fs_info);
+	return ret;
+}
+
+int btrfs_test_extent_buffer_operations(u32 sectorsize, u32 nodesize)
+{
+	test_msg("running extent buffer operation tests");
+	return test_btrfs_split_item(sectorsize, nodesize);
+}