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, 119 insertions, 0 deletions

diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h
new file mode 100644
index 000000000..01f448a78
--- /dev/null
+++ b/drivers/usb/class/cdc-acm.h
@@ -0,0 +1,119 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *
+ * Includes for cdc-acm.c
+ *
+ * Mainly take from usbnet's cdc-ether part
+ *
+ */
+
+/*
+ * Major and minor numbers.
+ */
+
+#define ACM_TTY_MAJOR		166
+#define ACM_TTY_MINORS		256
+
+#define ACM_MINOR_INVALID	ACM_TTY_MINORS
+
+/*
+ * Requests.
+ */
+
+#define USB_RT_ACM		(USB_TYPE_CLASS | USB_RECIP_INTERFACE)
+
+/*
+ * Internal driver structures.
+ */
+
+/*
+ * The only reason to have several buffers is to accommodate assumptions
+ * in line disciplines. They ask for empty space amount, receive our URB size,
+ * and proceed to issue several 1-character writes, assuming they will fit.
+ * The very first write takes a complete URB. Fortunately, this only happens
+ * when processing onlcr, so we only need 2 buffers. These values must be
+ * powers of 2.
+ */
+#define ACM_NW  16
+#define ACM_NR  16
+
+struct acm_wb {
+	u8 *buf;
+	dma_addr_t dmah;
+	unsigned int len;
+	struct urb		*urb;
+	struct acm		*instance;
+	bool use;
+};
+
+struct acm_rb {
+	int			size;
+	unsigned char		*base;
+	dma_addr_t		dma;
+	int			index;
+	struct acm		*instance;
+};
+
+struct acm {
+	struct usb_device *dev;				/* the corresponding usb device */
+	struct usb_interface *control;			/* control interface */
+	struct usb_interface *data;			/* data interface */
+	unsigned in, out;				/* i/o pipes */
+	struct tty_port port;			 	/* our tty port data */
+	struct urb *ctrlurb;				/* urbs */
+	u8 *ctrl_buffer;				/* buffers of urbs */
+	dma_addr_t ctrl_dma;				/* dma handles of buffers */
+	u8 *country_codes;				/* country codes from device */
+	unsigned int country_code_size;			/* size of this buffer */
+	unsigned int country_rel_date;			/* release date of version */
+	struct acm_wb wb[ACM_NW];
+	unsigned long read_urbs_free;
+	struct urb *read_urbs[ACM_NR];
+	struct acm_rb read_buffers[ACM_NR];
+	int rx_buflimit;
+	spinlock_t read_lock;
+	u8 *notification_buffer;			/* to reassemble fragmented notifications */
+	unsigned int nb_index;
+	unsigned int nb_size;
+	int transmitting;
+	spinlock_t write_lock;
+	struct mutex mutex;
+	bool disconnected;
+	unsigned long flags;
+#		define EVENT_TTY_WAKEUP	0
+#		define EVENT_RX_STALL	1
+#		define ACM_THROTTLED	2
+#		define ACM_ERROR_DELAY	3
+	unsigned long urbs_in_error_delay;		/* these need to be restarted after a delay */
+	struct usb_cdc_line_coding line;		/* bits, stop, parity */
+	struct delayed_work dwork;		        /* work queue entry for various purposes */
+	unsigned int ctrlin;				/* input control lines (DCD, DSR, RI, break, overruns) */
+	unsigned int ctrlout;				/* output control lines (DTR, RTS) */
+	struct async_icount iocount;			/* counters for control line changes */
+	struct async_icount oldcount;			/* for comparison of counter */
+	wait_queue_head_t wioctl;			/* for ioctl */
+	unsigned int writesize;				/* max packet size for the output bulk endpoint */
+	unsigned int readsize,ctrlsize;			/* buffer sizes for freeing */
+	unsigned int minor;				/* acm minor number */
+	unsigned char clocal;				/* termios CLOCAL */
+	unsigned int ctrl_caps;				/* control capabilities from the class specific header */
+	unsigned int susp_count;			/* number of suspended interfaces */
+	unsigned int combined_interfaces:1;		/* control and data collapsed */
+	u8 bInterval;
+	struct usb_anchor delayed;			/* writes queued for a device about to be woken */
+	unsigned long quirks;
+};
+
+/* constants describing various quirks and errors */
+#define NO_UNION_NORMAL			BIT(0)
+#define SINGLE_RX_URB			BIT(1)
+#define NO_CAP_LINE			BIT(2)
+#define IGNORE_DEVICE			BIT(3)
+#define QUIRK_CONTROL_LINE_STATE	BIT(4)
+#define CLEAR_HALT_CONDITIONS		BIT(5)
+#define SEND_ZERO_PACKET		BIT(6)
+#define DISABLE_ECHO			BIT(7)
+#define MISSING_CAP_BRK			BIT(8)
+#define NO_UNION_12			BIT(9)
+#define VENDOR_CLASS_DATA_IFACE		BIT(10)  /* data interface uses vendor-specific class */
+#define ALWAYS_POLL_CTRL		BIT(11) /* keep ctrl URB active even without an open TTY */