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, 59 insertions, 0 deletions

diff --git a/drivers/gpib/include/amccs5933.h b/drivers/gpib/include/amccs5933.h
new file mode 100644
index 000000000..f8a80bdc7
--- /dev/null
+++ b/drivers/gpib/include/amccs5933.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/***************************************************************************
+ * Registers and bits for amccs5933 pci chip
+ *    copyright            : (C) 2002 by Frank Mori Hess
+ ***************************************************************************/
+
+// register offsets
+enum {
+	MBEF_REG = 0x34,	// mailbux empty/full
+	INTCSR_REG = 0x38,	// interrupt control and status
+	BMCSR_REG = 0x3c,	// bus master control and status
+};
+
+// incoming mailbox 0-3  register offsets
+static inline int INCOMING_MAILBOX_REG(unsigned int mailbox)
+{
+	return (0x10 + 4 * mailbox);
+};
+
+// bit definitions
+
+// INTCSR bits
+enum {
+	OUTBOX_EMPTY_INTR_BIT = 0x10,	// enable outbox empty interrupt
+	INBOX_FULL_INTR_BIT = 0x1000,	// enable inbox full interrupt
+	INBOX_INTR_CS_BIT = 0x20000,	// read, or write clear inbox full interrupt
+	INTR_ASSERTED_BIT = 0x800000,	// read only, interrupt asserted
+};
+
+// select byte 0 to 3 of incoming mailbox
+static inline int INBOX_BYTE_BITS(unsigned int byte)
+{
+	return (byte & 0x3) << 8;
+};
+
+// select incoming mailbox 0 to 3
+static inline int INBOX_SELECT_BITS(unsigned int mailbox)
+{
+	return (mailbox & 0x3) << 10;
+};
+
+// select byte 0 to 3 of outgoing mailbox
+static inline int OUTBOX_BYTE_BITS(unsigned int byte)
+{
+	return (byte & 0x3);
+};
+
+// select outgoing mailbox 0 to 3
+static inline int OUTBOX_SELECT_BITS(unsigned int mailbox)
+{
+	return (mailbox & 0x3) << 2;
+};
+
+// BMCSR bits
+enum {
+	MBOX_FLAGS_RESET_BIT = 0x08000000,	// resets mailbox empty/full flags
+};
+