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, 159 insertions, 0 deletions

diff --git a/drivers/interconnect/bulk.c b/drivers/interconnect/bulk.c
new file mode 100644
index 000000000..8b1d8a412
--- /dev/null
+++ b/drivers/interconnect/bulk.c
@@ -0,0 +1,159 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/interconnect-provider.h>
+#include <linux/device.h>
+#include <linux/export.h>
+
+/**
+ * of_icc_bulk_get() - get interconnect paths
+ * @dev: the device requesting the path
+ * @num_paths: the number of icc_bulk_data
+ * @paths: the table with the paths we want to get
+ *
+ * Returns 0 on success or negative errno otherwise.
+ */
+int __must_check of_icc_bulk_get(struct device *dev, int num_paths,
+				 struct icc_bulk_data *paths)
+{
+	int ret, i;
+
+	for (i = 0; i < num_paths; i++) {
+		paths[i].path = of_icc_get(dev, paths[i].name);
+		if (IS_ERR(paths[i].path)) {
+			ret = PTR_ERR(paths[i].path);
+			if (ret != -EPROBE_DEFER)
+				dev_err(dev, "of_icc_get() failed on path %s (%d)\n",
+					paths[i].name, ret);
+			paths[i].path = NULL;
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	icc_bulk_put(i, paths);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(of_icc_bulk_get);
+
+/**
+ * icc_bulk_put() - put a list of interconnect paths
+ * @num_paths: the number of icc_bulk_data
+ * @paths: the icc_bulk_data table with the paths being put
+ */
+void icc_bulk_put(int num_paths, struct icc_bulk_data *paths)
+{
+	while (--num_paths >= 0) {
+		icc_put(paths[num_paths].path);
+		paths[num_paths].path = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(icc_bulk_put);
+
+/**
+ * icc_bulk_set_bw() - set bandwidth to a set of paths
+ * @num_paths: the number of icc_bulk_data
+ * @paths: the icc_bulk_data table containing the paths and bandwidth
+ *
+ * Returns 0 on success or negative errno otherwise.
+ */
+int icc_bulk_set_bw(int num_paths, const struct icc_bulk_data *paths)
+{
+	int ret = 0;
+	int i;
+
+	for (i = 0; i < num_paths; i++) {
+		ret = icc_set_bw(paths[i].path, paths[i].avg_bw, paths[i].peak_bw);
+		if (ret) {
+			pr_err("icc_set_bw() failed on path %s (%d)\n", paths[i].name, ret);
+			return ret;
+		}
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(icc_bulk_set_bw);
+
+/**
+ * icc_bulk_enable() - enable a previously disabled set of paths
+ * @num_paths: the number of icc_bulk_data
+ * @paths: the icc_bulk_data table containing the paths and bandwidth
+ *
+ * Returns 0 on success or negative errno otherwise.
+ */
+int icc_bulk_enable(int num_paths, const struct icc_bulk_data *paths)
+{
+	int ret, i;
+
+	for (i = 0; i < num_paths; i++) {
+		ret = icc_enable(paths[i].path);
+		if (ret) {
+			pr_err("icc_enable() failed on path %s (%d)\n", paths[i].name, ret);
+			goto err;
+		}
+	}
+
+	return 0;
+
+err:
+	icc_bulk_disable(i, paths);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(icc_bulk_enable);
+
+/**
+ * icc_bulk_disable() - disable a set of interconnect paths
+ * @num_paths: the number of icc_bulk_data
+ * @paths: the icc_bulk_data table containing the paths and bandwidth
+ */
+void icc_bulk_disable(int num_paths, const struct icc_bulk_data *paths)
+{
+	while (--num_paths >= 0)
+		icc_disable(paths[num_paths].path);
+}
+EXPORT_SYMBOL_GPL(icc_bulk_disable);
+
+struct icc_bulk_devres {
+	struct icc_bulk_data *paths;
+	int num_paths;
+};
+
+static void devm_icc_bulk_release(struct device *dev, void *res)
+{
+	struct icc_bulk_devres *devres = res;
+
+	icc_bulk_put(devres->num_paths, devres->paths);
+}
+
+/**
+ * devm_of_icc_bulk_get() - resource managed of_icc_bulk_get
+ * @dev: the device requesting the path
+ * @num_paths: the number of icc_bulk_data
+ * @paths: the table with the paths we want to get
+ *
+ * Returns 0 on success or negative errno otherwise.
+ */
+int devm_of_icc_bulk_get(struct device *dev, int num_paths, struct icc_bulk_data *paths)
+{
+	struct icc_bulk_devres *devres;
+	int ret;
+
+	devres = devres_alloc(devm_icc_bulk_release, sizeof(*devres), GFP_KERNEL);
+	if (!devres)
+		return -ENOMEM;
+
+	ret = of_icc_bulk_get(dev, num_paths, paths);
+	if (!ret) {
+		devres->paths = paths;
+		devres->num_paths = num_paths;
+		devres_add(dev, devres);
+	} else {
+		devres_free(devres);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devm_of_icc_bulk_get);