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>

4 files changed, 143 insertions, 0 deletions

diff --git a/tools/testing/rbtree/Makefile b/tools/testing/rbtree/Makefile
new file mode 100644
index 000000000..d7bbae2af
--- /dev/null
+++ b/tools/testing/rbtree/Makefile
@@ -0,0 +1,33 @@
+# SPDX-License-Identifier: GPL-2.0
+
+.PHONY: clean
+
+TARGETS = rbtree_test interval_tree_test
+OFILES = $(SHARED_OFILES) rbtree-shim.o interval_tree-shim.o maple-shim.o
+DEPS = ../../../include/linux/rbtree.h \
+	../../../include/linux/rbtree_types.h \
+	../../../include/linux/rbtree_augmented.h \
+	../../../include/linux/interval_tree.h \
+	../../../include/linux/interval_tree_generic.h \
+	../../../lib/rbtree.c \
+	../../../lib/interval_tree.c
+
+targets: $(TARGETS)
+
+include ../shared/shared.mk
+
+ifeq ($(DEBUG), 1)
+	CFLAGS += -g
+endif
+
+$(TARGETS):	$(OFILES)
+
+rbtree-shim.o: $(DEPS)
+rbtree_test.o:  ../../../lib/rbtree_test.c
+interval_tree-shim.o: $(DEPS)
+interval_tree-shim.o: CFLAGS += -DCONFIG_INTERVAL_TREE_SPAN_ITER
+interval_tree_test.o: 	../../../lib/interval_tree_test.c
+interval_tree_test.o: CFLAGS += -DCONFIG_INTERVAL_TREE_SPAN_ITER
+
+clean:
+	$(RM) $(TARGETS) *.o radix-tree.c idr.c generated/*
diff --git a/tools/testing/rbtree/interval_tree_test.c b/tools/testing/rbtree/interval_tree_test.c
new file mode 100644
index 000000000..49bc5b534
--- /dev/null
+++ b/tools/testing/rbtree/interval_tree_test.c
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * interval_tree.c: Userspace Interval Tree test-suite
+ * Copyright (c) 2025 Wei Yang <richard.weiyang@gmail.com>
+ */
+#include <linux/math64.h>
+#include <linux/kern_levels.h>
+#include "shared.h"
+#include "maple-shared.h"
+
+#include "../../../lib/interval_tree_test.c"
+
+int usage(void)
+{
+	fprintf(stderr, "Userland interval tree test cases\n");
+	fprintf(stderr, "  -n: Number of nodes in the interval tree\n");
+	fprintf(stderr, "  -p: Number of iterations modifying the tree\n");
+	fprintf(stderr, "  -q: Number of searches to the interval tree\n");
+	fprintf(stderr, "  -s: Number of iterations searching the tree\n");
+	fprintf(stderr, "  -a: Searches will iterate all nodes in the tree\n");
+	fprintf(stderr, "  -m: Largest value for the interval's endpoint\n");
+	fprintf(stderr, "  -r: Random seed\n");
+	exit(-1);
+}
+
+void interval_tree_tests(void)
+{
+	interval_tree_test_init();
+	interval_tree_test_exit();
+}
+
+int main(int argc, char **argv)
+{
+	int opt;
+
+	while ((opt = getopt(argc, argv, "n:p:q:s:am:r:")) != -1) {
+		if (opt == 'n')
+			nnodes = strtoul(optarg, NULL, 0);
+		else if (opt == 'p')
+			perf_loops = strtoul(optarg, NULL, 0);
+		else if (opt == 'q')
+			nsearches = strtoul(optarg, NULL, 0);
+		else if (opt == 's')
+			search_loops = strtoul(optarg, NULL, 0);
+		else if (opt == 'a')
+			search_all = true;
+		else if (opt == 'm')
+			max_endpoint = strtoul(optarg, NULL, 0);
+		else if (opt == 'r')
+			seed = strtoul(optarg, NULL, 0);
+		else
+			usage();
+	}
+
+	maple_tree_init();
+	interval_tree_tests();
+	return 0;
+}
diff --git a/tools/testing/rbtree/rbtree_test.c b/tools/testing/rbtree/rbtree_test.c
new file mode 100644
index 000000000..585c970f6
--- /dev/null
+++ b/tools/testing/rbtree/rbtree_test.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * rbtree_test.c: Userspace Red Black Tree test-suite
+ * Copyright (c) 2025 Wei Yang <richard.weiyang@gmail.com>
+ */
+#include <linux/init.h>
+#include <linux/math64.h>
+#include <linux/kern_levels.h>
+#include "shared.h"
+
+#include "../../../lib/rbtree_test.c"
+
+int usage(void)
+{
+	fprintf(stderr, "Userland rbtree test cases\n");
+	fprintf(stderr, "  -n: Number of nodes in the rb-tree\n");
+	fprintf(stderr, "  -p: Number of iterations modifying the rb-tree\n");
+	fprintf(stderr, "  -c: Number of iterations modifying and verifying the rb-tree\n");
+	fprintf(stderr, "  -r: Random seed\n");
+	exit(-1);
+}
+
+void rbtree_tests(void)
+{
+	rbtree_test_init();
+	rbtree_test_exit();
+}
+
+int main(int argc, char **argv)
+{
+	int opt;
+
+	while ((opt = getopt(argc, argv, "n:p:c:r:")) != -1) {
+		if (opt == 'n')
+			nnodes = strtoul(optarg, NULL, 0);
+		else if (opt == 'p')
+			perf_loops = strtoul(optarg, NULL, 0);
+		else if (opt == 'c')
+			check_loops = strtoul(optarg, NULL, 0);
+		else if (opt == 'r')
+			seed = strtoul(optarg, NULL, 0);
+		else
+			usage();
+	}
+
+	rbtree_tests();
+	return 0;
+}
diff --git a/tools/testing/rbtree/test.h b/tools/testing/rbtree/test.h
new file mode 100644
index 000000000..f1f1b545b
--- /dev/null
+++ b/tools/testing/rbtree/test.h
@@ -0,0 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+void rbtree_tests(void);
+void interval_tree_tests(void);