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, 58 insertions, 0 deletions

diff --git a/include/video/pmagb-b-fb.h b/include/video/pmagb-b-fb.h
new file mode 100644
index 000000000..7539b9087
--- /dev/null
+++ b/include/video/pmagb-b-fb.h
@@ -0,0 +1,58 @@
+/*
+ *	linux/include/video/pmagb-b-fb.h
+ *
+ *	TURBOchannel PMAGB-B Smart Frame Buffer (SFB) card support,
+ *	Copyright (C) 1999, 2000, 2001 by
+ *	Michael Engel <engel@unix-ag.org> and
+ *	Karsten Merker <merker@linuxtag.org>
+ *	Copyright (c) 2005  Maciej W. Rozycki
+ *
+ *	This file is subject to the terms and conditions of the GNU General
+ *	Public License.  See the file COPYING in the main directory of this
+ *	archive for more details.
+ */
+
+/* IOmem resource offsets.  */
+#define PMAGB_B_ROM		0x000000	/* REX option ROM */
+#define PMAGB_B_SFB		0x100000	/* SFB ASIC */
+#define PMAGB_B_GP0		0x140000	/* general purpose output 0 */
+#define PMAGB_B_GP1		0x180000	/* general purpose output 1 */
+#define PMAGB_B_BT459		0x1c0000	/* Bt459 RAMDAC */
+#define PMAGB_B_FBMEM		0x200000	/* frame buffer */
+#define PMAGB_B_SIZE		0x400000	/* address space size */
+
+/* IOmem register offsets.  */
+#define SFB_REG_VID_HOR		0x64		/* video horizontal setup */
+#define SFB_REG_VID_VER		0x68		/* video vertical setup */
+#define SFB_REG_VID_BASE	0x6c		/* video base address */
+#define SFB_REG_TCCLK_COUNT	0x78		/* TURBOchannel clock count */
+#define SFB_REG_VIDCLK_COUNT	0x7c		/* video clock count */
+
+/* Video horizontal setup register constants.  All bits are r/w.  */
+#define SFB_VID_HOR_BP_SHIFT	0x15		/* back porch */
+#define SFB_VID_HOR_BP_MASK	0x7f
+#define SFB_VID_HOR_SYN_SHIFT	0x0e		/* sync pulse */
+#define SFB_VID_HOR_SYN_MASK	0x7f
+#define SFB_VID_HOR_FP_SHIFT	0x09		/* front porch */
+#define SFB_VID_HOR_FP_MASK	0x1f
+#define SFB_VID_HOR_PIX_SHIFT	0x00		/* active video */
+#define SFB_VID_HOR_PIX_MASK	0x1ff
+
+/* Video vertical setup register constants.  All bits are r/w.  */
+#define SFB_VID_VER_BP_SHIFT	0x16		/* back porch */
+#define SFB_VID_VER_BP_MASK	0x3f
+#define SFB_VID_VER_SYN_SHIFT	0x10		/* sync pulse */
+#define SFB_VID_VER_SYN_MASK	0x3f
+#define SFB_VID_VER_FP_SHIFT	0x0b		/* front porch */
+#define SFB_VID_VER_FP_MASK	0x1f
+#define SFB_VID_VER_SL_SHIFT	0x00		/* active scan lines */
+#define SFB_VID_VER_SL_MASK	0x7ff
+
+/* Video base address register constants.  All bits are r/w.  */
+#define SFB_VID_BASE_MASK	0x1ff		/* video base row address */
+
+/* Bt459 register offsets, byte-wide registers.  */
+#define BT459_ADDR_LO		0x0		/* address low */
+#define BT459_ADDR_HI		0x4		/* address high */
+#define BT459_DATA		0x8		/* data window register */
+#define BT459_CMAP		0xc		/* color map window register */