x86/amd_node: Fix PCI device reference counting in amd_smn_init()grafted

The local "root" pointer is a temporary variable used during the device
search. Therefore, refcount related to the search iterators should be cleaned
up after the search is complete.

Use the __free() cleanup macro to ensure the refcount is decremented when the
temporary pointer goes out of scope.

Additionally, increment the refcount when caching a root pointer. This ensures
the in-use refcount is separate from the temporary search refcounting.

Finally, drop the redundant "root = NULL" before the second search loop. The
pci_get_class() iterator always decrements the refcount of its "from"
argument, so the first loop can only fall through with "root" already NULL.

Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching")
Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com
Reported-by: Sashiko <sashiko-bot@kernel.org>
Assisted-by: LLM
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Cc: <stable@kernel.org>
Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com

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");