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, 70 insertions, 0 deletions

diff --git a/drivers/scsi/a2091.h b/drivers/scsi/a2091.h
new file mode 100644
index 000000000..8d8a4074a
--- /dev/null
+++ b/drivers/scsi/a2091.h
@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef A2091_H
+#define A2091_H
+
+/* $Id: a2091.h,v 1.4 1997/01/19 23:07:09 davem Exp $
+ *
+ * Header file for the Commodore A2091 Zorro II SCSI controller for Linux
+ *
+ * Written and (C) 1993, Hamish Macdonald, see a2091.c for more info
+ *
+ */
+
+#include <linux/types.h>
+
+#ifndef CMD_PER_LUN
+#define CMD_PER_LUN		2
+#endif
+
+#ifndef CAN_QUEUE
+#define CAN_QUEUE		16
+#endif
+
+/*
+ * if the transfer address ANDed with this results in a non-zero
+ * result, then we can't use DMA.
+ */
+#define A2091_XFER_MASK		(0xff000001)
+
+struct a2091_scsiregs {
+		 unsigned char	pad1[64];
+	volatile unsigned short	ISTR;
+	volatile unsigned short	CNTR;
+		 unsigned char	pad2[60];
+	volatile unsigned int	WTC;
+	volatile unsigned long	ACR;
+		 unsigned char	pad3[6];
+	volatile unsigned short	DAWR;
+		 unsigned char	pad4;
+	volatile unsigned char	SASR;
+		 unsigned char	pad5;
+	volatile unsigned char	SCMD;
+		 unsigned char	pad6[76];
+	volatile unsigned short	ST_DMA;
+	volatile unsigned short	SP_DMA;
+	volatile unsigned short	CINT;
+		 unsigned char	pad7[2];
+	volatile unsigned short	FLUSH;
+};
+
+#define DAWR_A2091		(3)
+
+/* CNTR bits. */
+#define CNTR_TCEN		(1<<7)
+#define CNTR_PREST		(1<<6)
+#define CNTR_PDMD		(1<<5)
+#define CNTR_INTEN		(1<<4)
+#define CNTR_DDIR		(1<<3)
+
+/* ISTR bits. */
+#define ISTR_INTX		(1<<8)
+#define ISTR_INT_F		(1<<7)
+#define ISTR_INTS		(1<<6)
+#define ISTR_E_INT		(1<<5)
+#define ISTR_INT_P		(1<<4)
+#define ISTR_UE_INT		(1<<3)
+#define ISTR_OE_INT		(1<<2)
+#define ISTR_FF_FLG		(1<<1)
+#define ISTR_FE_FLG		(1<<0)
+
+#endif /* A2091_H */