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, 47 insertions, 0 deletions

diff --git a/drivers/interconnect/internal.h b/drivers/interconnect/internal.h
new file mode 100644
index 000000000..3b9d50589
--- /dev/null
+++ b/drivers/interconnect/internal.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Interconnect framework internal structs
+ *
+ * Copyright (c) 2019, Linaro Ltd.
+ * Author: Georgi Djakov <georgi.djakov@linaro.org>
+ */
+
+#ifndef __DRIVERS_INTERCONNECT_INTERNAL_H
+#define __DRIVERS_INTERCONNECT_INTERNAL_H
+
+/**
+ * struct icc_req - constraints that are attached to each node
+ * @req_node: entry in list of requests for the particular @node
+ * @node: the interconnect node to which this constraint applies
+ * @dev: reference to the device that sets the constraints
+ * @enabled: indicates whether the path with this request is enabled
+ * @tag: path tag (optional)
+ * @avg_bw: an integer describing the average bandwidth in kBps
+ * @peak_bw: an integer describing the peak bandwidth in kBps
+ */
+struct icc_req {
+	struct hlist_node req_node;
+	struct icc_node *node;
+	struct device *dev;
+	bool enabled;
+	u32 tag;
+	u32 avg_bw;
+	u32 peak_bw;
+};
+
+/**
+ * struct icc_path - interconnect path structure
+ * @name: a string name of the path (useful for ftrace)
+ * @num_nodes: number of hops (nodes)
+ * @reqs: array of the requests applicable to this path of nodes
+ */
+struct icc_path {
+	const char *name;
+	size_t num_nodes;
+	struct icc_req reqs[] __counted_by(num_nodes);
+};
+
+struct icc_path *icc_get(struct device *dev, const char *src, const char *dst);
+int icc_debugfs_client_init(struct dentry *icc_dir);
+
+#endif