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, 33 insertions, 0 deletions

diff --git a/drivers/char/tpm/tpm-dev.h b/drivers/char/tpm/tpm-dev.h
new file mode 100644
index 000000000..f3742bcc7
--- /dev/null
+++ b/drivers/char/tpm/tpm-dev.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _TPM_DEV_H
+#define _TPM_DEV_H
+
+#include <linux/poll.h>
+#include "tpm.h"
+
+struct file_priv {
+	struct tpm_chip *chip;
+	struct tpm_space *space;
+
+	struct mutex buffer_mutex;
+	struct timer_list user_read_timer;      /* user needs to claim result */
+	struct work_struct timeout_work;
+	struct work_struct async_work;
+	wait_queue_head_t async_wait;
+	ssize_t response_length;
+	bool response_read;
+	bool command_enqueued;
+
+	u8 data_buffer[TPM_BUFSIZE];
+};
+
+void tpm_common_open(struct file *file, struct tpm_chip *chip,
+		     struct file_priv *priv, struct tpm_space *space);
+ssize_t tpm_common_read(struct file *file, char __user *buf,
+			size_t size, loff_t *off);
+ssize_t tpm_common_write(struct file *file, const char __user *buf,
+			 size_t size, loff_t *off);
+__poll_t tpm_common_poll(struct file *file, poll_table *wait);
+
+void tpm_common_release(struct file *file, struct file_priv *priv);
+#endif