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, 230 insertions, 0 deletions

diff --git a/drivers/bluetooth/btqcomsmd.c b/drivers/bluetooth/btqcomsmd.c
new file mode 100644
index 000000000..d2e13fcb6
--- /dev/null
+++ b/drivers/bluetooth/btqcomsmd.c
@@ -0,0 +1,230 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2016, Linaro Ltd.
+ * Copyright (c) 2015, Sony Mobile Communications Inc.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/rpmsg.h>
+#include <linux/of.h>
+
+#include <linux/soc/qcom/wcnss_ctrl.h>
+#include <linux/platform_device.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "btqca.h"
+
+struct btqcomsmd {
+	struct hci_dev *hdev;
+
+	struct rpmsg_endpoint *acl_channel;
+	struct rpmsg_endpoint *cmd_channel;
+};
+
+static int btqcomsmd_recv(struct hci_dev *hdev, unsigned int type,
+			   const void *data, size_t count)
+{
+	struct sk_buff *skb;
+
+	/* Use GFP_ATOMIC as we're in IRQ context */
+	skb = bt_skb_alloc(count, GFP_ATOMIC);
+	if (!skb) {
+		hdev->stat.err_rx++;
+		return -ENOMEM;
+	}
+
+	hci_skb_pkt_type(skb) = type;
+	skb_put_data(skb, data, count);
+
+	return hci_recv_frame(hdev, skb);
+}
+
+static int btqcomsmd_acl_callback(struct rpmsg_device *rpdev, void *data,
+				  int count, void *priv, u32 addr)
+{
+	struct btqcomsmd *btq = priv;
+
+	btq->hdev->stat.byte_rx += count;
+	return btqcomsmd_recv(btq->hdev, HCI_ACLDATA_PKT, data, count);
+}
+
+static int btqcomsmd_cmd_callback(struct rpmsg_device *rpdev, void *data,
+				  int count, void *priv, u32 addr)
+{
+	struct btqcomsmd *btq = priv;
+
+	btq->hdev->stat.byte_rx += count;
+	return btqcomsmd_recv(btq->hdev, HCI_EVENT_PKT, data, count);
+}
+
+static int btqcomsmd_send(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct btqcomsmd *btq = hci_get_drvdata(hdev);
+	int ret;
+
+	switch (hci_skb_pkt_type(skb)) {
+	case HCI_ACLDATA_PKT:
+		ret = rpmsg_send(btq->acl_channel, skb->data, skb->len);
+		if (ret) {
+			hdev->stat.err_tx++;
+			break;
+		}
+		hdev->stat.acl_tx++;
+		hdev->stat.byte_tx += skb->len;
+		break;
+	case HCI_COMMAND_PKT:
+		ret = rpmsg_send(btq->cmd_channel, skb->data, skb->len);
+		if (ret) {
+			hdev->stat.err_tx++;
+			break;
+		}
+		hdev->stat.cmd_tx++;
+		hdev->stat.byte_tx += skb->len;
+		break;
+	default:
+		ret = -EILSEQ;
+		break;
+	}
+
+	if (!ret)
+		kfree_skb(skb);
+
+	return ret;
+}
+
+static int btqcomsmd_open(struct hci_dev *hdev)
+{
+	return 0;
+}
+
+static int btqcomsmd_close(struct hci_dev *hdev)
+{
+	return 0;
+}
+
+static int btqcomsmd_setup(struct hci_dev *hdev)
+{
+	struct sk_buff *skb;
+
+	skb = __hci_cmd_sync(hdev, HCI_OP_RESET, 0, NULL, HCI_INIT_TIMEOUT);
+	if (IS_ERR(skb))
+		return PTR_ERR(skb);
+	kfree_skb(skb);
+
+	/* Devices do not have persistent storage for BD address. Retrieve
+	 * it from the firmware node property.
+	 */
+	hci_set_quirk(hdev, HCI_QUIRK_USE_BDADDR_PROPERTY);
+
+	return 0;
+}
+
+static int btqcomsmd_set_bdaddr(struct hci_dev *hdev, const bdaddr_t *bdaddr)
+{
+	int ret;
+
+	ret = qca_set_bdaddr_rome(hdev, bdaddr);
+	if (ret)
+		return ret;
+
+	/* The firmware stops responding for a while after setting the bdaddr,
+	 * causing timeouts for subsequent commands. Sleep a bit to avoid this.
+	 */
+	usleep_range(1000, 10000);
+	return 0;
+}
+
+static int btqcomsmd_probe(struct platform_device *pdev)
+{
+	struct btqcomsmd *btq;
+	struct hci_dev *hdev;
+	void *wcnss;
+	int ret;
+
+	btq = devm_kzalloc(&pdev->dev, sizeof(*btq), GFP_KERNEL);
+	if (!btq)
+		return -ENOMEM;
+
+	wcnss = dev_get_drvdata(pdev->dev.parent);
+
+	btq->acl_channel = qcom_wcnss_open_channel(wcnss, "APPS_RIVA_BT_ACL",
+						   btqcomsmd_acl_callback, btq);
+	if (IS_ERR(btq->acl_channel))
+		return PTR_ERR(btq->acl_channel);
+
+	btq->cmd_channel = qcom_wcnss_open_channel(wcnss, "APPS_RIVA_BT_CMD",
+						   btqcomsmd_cmd_callback, btq);
+	if (IS_ERR(btq->cmd_channel)) {
+		ret = PTR_ERR(btq->cmd_channel);
+		goto destroy_acl_channel;
+	}
+
+	hdev = hci_alloc_dev();
+	if (!hdev) {
+		ret = -ENOMEM;
+		goto destroy_cmd_channel;
+	}
+
+	hci_set_drvdata(hdev, btq);
+	btq->hdev = hdev;
+	SET_HCIDEV_DEV(hdev, &pdev->dev);
+
+	hdev->bus = HCI_SMD;
+	hdev->open = btqcomsmd_open;
+	hdev->close = btqcomsmd_close;
+	hdev->send = btqcomsmd_send;
+	hdev->setup = btqcomsmd_setup;
+	hdev->set_bdaddr = btqcomsmd_set_bdaddr;
+
+	ret = hci_register_dev(hdev);
+	if (ret < 0)
+		goto hci_free_dev;
+
+	platform_set_drvdata(pdev, btq);
+
+	return 0;
+
+hci_free_dev:
+	hci_free_dev(hdev);
+destroy_cmd_channel:
+	rpmsg_destroy_ept(btq->cmd_channel);
+destroy_acl_channel:
+	rpmsg_destroy_ept(btq->acl_channel);
+
+	return ret;
+}
+
+static void btqcomsmd_remove(struct platform_device *pdev)
+{
+	struct btqcomsmd *btq = platform_get_drvdata(pdev);
+
+	hci_unregister_dev(btq->hdev);
+	hci_free_dev(btq->hdev);
+
+	rpmsg_destroy_ept(btq->cmd_channel);
+	rpmsg_destroy_ept(btq->acl_channel);
+}
+
+static const struct of_device_id btqcomsmd_of_match[] = {
+	{ .compatible = "qcom,wcnss-bt", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, btqcomsmd_of_match);
+
+static struct platform_driver btqcomsmd_driver = {
+	.probe = btqcomsmd_probe,
+	.remove = btqcomsmd_remove,
+	.driver  = {
+		.name  = "btqcomsmd",
+		.of_match_table = btqcomsmd_of_match,
+	},
+};
+
+module_platform_driver(btqcomsmd_driver);
+
+MODULE_AUTHOR("Bjorn Andersson <bjorn.andersson@sonymobile.com>");
+MODULE_DESCRIPTION("Qualcomm SMD HCI driver");
+MODULE_LICENSE("GPL v2");