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, 203 insertions, 0 deletions

diff --git a/drivers/interconnect/icc-clk.c b/drivers/interconnect/icc-clk.c
new file mode 100644
index 000000000..93c030608
--- /dev/null
+++ b/drivers/interconnect/icc-clk.c
@@ -0,0 +1,203 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2023, Linaro Ltd.
+ */
+
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/interconnect-clk.h>
+#include <linux/interconnect-provider.h>
+
+struct icc_clk_node {
+	struct clk *clk;
+	bool enabled;
+};
+
+struct icc_clk_provider {
+	struct icc_provider provider;
+	int num_clocks;
+	struct icc_clk_node clocks[] __counted_by(num_clocks);
+};
+
+#define to_icc_clk_provider(_provider) \
+	container_of(_provider, struct icc_clk_provider, provider)
+
+static int icc_clk_set(struct icc_node *src, struct icc_node *dst)
+{
+	struct icc_clk_node *qn = src->data;
+	int ret;
+
+	if (!qn || !qn->clk)
+		return 0;
+
+	if (!src->peak_bw) {
+		if (qn->enabled)
+			clk_disable_unprepare(qn->clk);
+		qn->enabled = false;
+
+		return 0;
+	}
+
+	if (!qn->enabled) {
+		ret = clk_prepare_enable(qn->clk);
+		if (ret)
+			return ret;
+		qn->enabled = true;
+	}
+
+	return clk_set_rate(qn->clk, icc_units_to_bps(src->peak_bw));
+}
+
+static int icc_clk_get_bw(struct icc_node *node, u32 *avg, u32 *peak)
+{
+	struct icc_clk_node *qn = node->data;
+
+	if (!qn || !qn->clk)
+		*peak = INT_MAX;
+	else
+		*peak = Bps_to_icc(clk_get_rate(qn->clk));
+
+	return 0;
+}
+
+/**
+ * icc_clk_register() - register a new clk-based interconnect provider
+ * @dev: device supporting this provider
+ * @first_id: an ID of the first provider's node
+ * @num_clocks: number of instances of struct icc_clk_data
+ * @data: data for the provider
+ *
+ * Registers and returns a clk-based interconnect provider. It is a simple
+ * wrapper around COMMON_CLK framework, allowing other devices to vote on the
+ * clock rate.
+ *
+ * Return: 0 on success, or an error code otherwise
+ */
+struct icc_provider *icc_clk_register(struct device *dev,
+				      unsigned int first_id,
+				      unsigned int num_clocks,
+				      const struct icc_clk_data *data)
+{
+	struct icc_clk_provider *qp;
+	struct icc_provider *provider;
+	struct icc_onecell_data *onecell;
+	struct icc_node *node;
+	int ret, i, j;
+
+	onecell = devm_kzalloc(dev, struct_size(onecell, nodes, 2 * num_clocks), GFP_KERNEL);
+	if (!onecell)
+		return ERR_PTR(-ENOMEM);
+	onecell->num_nodes = 2 * num_clocks;
+
+	qp = devm_kzalloc(dev, struct_size(qp, clocks, num_clocks), GFP_KERNEL);
+	if (!qp)
+		return ERR_PTR(-ENOMEM);
+
+	qp->num_clocks = num_clocks;
+
+	provider = &qp->provider;
+	provider->dev = dev;
+	provider->get_bw = icc_clk_get_bw;
+	provider->set = icc_clk_set;
+	provider->aggregate = icc_std_aggregate;
+	provider->xlate = of_icc_xlate_onecell;
+	INIT_LIST_HEAD(&provider->nodes);
+	provider->data = onecell;
+
+	icc_provider_init(provider);
+
+	for (i = 0, j = 0; i < num_clocks; i++) {
+		qp->clocks[i].clk = data[i].clk;
+
+		node = icc_node_create(first_id + data[i].master_id);
+		if (IS_ERR(node)) {
+			ret = PTR_ERR(node);
+			goto err;
+		}
+
+		node->name = devm_kasprintf(dev, GFP_KERNEL, "%s_master", data[i].name);
+		if (!node->name) {
+			icc_node_destroy(node->id);
+			ret = -ENOMEM;
+			goto err;
+		}
+
+		node->data = &qp->clocks[i];
+		icc_node_add(node, provider);
+		/* link to the next node, slave */
+		icc_link_create(node, first_id + data[i].slave_id);
+		onecell->nodes[j++] = node;
+
+		node = icc_node_create(first_id + data[i].slave_id);
+		if (IS_ERR(node)) {
+			ret = PTR_ERR(node);
+			goto err;
+		}
+
+		node->name = devm_kasprintf(dev, GFP_KERNEL, "%s_slave", data[i].name);
+		if (!node->name) {
+			icc_node_destroy(node->id);
+			ret = -ENOMEM;
+			goto err;
+		}
+
+		/* no data for slave node */
+		icc_node_add(node, provider);
+		onecell->nodes[j++] = node;
+	}
+
+	ret = icc_provider_register(provider);
+	if (ret)
+		goto err;
+
+	return provider;
+
+err:
+	icc_nodes_remove(provider);
+
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(icc_clk_register);
+
+static void devm_icc_release(void *res)
+{
+	icc_clk_unregister(res);
+}
+
+int devm_icc_clk_register(struct device *dev, unsigned int first_id,
+			  unsigned int num_clocks, const struct icc_clk_data *data)
+{
+	struct icc_provider *prov;
+
+	prov = icc_clk_register(dev, first_id, num_clocks, data);
+	if (IS_ERR(prov))
+		return PTR_ERR(prov);
+
+	return devm_add_action_or_reset(dev, devm_icc_release, prov);
+}
+EXPORT_SYMBOL_GPL(devm_icc_clk_register);
+
+/**
+ * icc_clk_unregister() - unregister a previously registered clk interconnect provider
+ * @provider: provider returned by icc_clk_register()
+ */
+void icc_clk_unregister(struct icc_provider *provider)
+{
+	struct icc_clk_provider *qp = container_of(provider, struct icc_clk_provider, provider);
+	int i;
+
+	icc_provider_deregister(&qp->provider);
+	icc_nodes_remove(&qp->provider);
+
+	for (i = 0; i < qp->num_clocks; i++) {
+		struct icc_clk_node *qn = &qp->clocks[i];
+
+		if (qn->enabled)
+			clk_disable_unprepare(qn->clk);
+	}
+}
+EXPORT_SYMBOL_GPL(icc_clk_unregister);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Interconnect wrapper for clocks");
+MODULE_AUTHOR("Dmitry Baryshkov <dmitry.baryshkov@linaro.org>");