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, 57 insertions, 0 deletions

diff --git a/arch/powerpc/boot/redboot.h b/arch/powerpc/boot/redboot.h
new file mode 100644
index 000000000..8f319b1ad
--- /dev/null
+++ b/arch/powerpc/boot/redboot.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PPC_REDBOOT_H
+#define _PPC_REDBOOT_H
+
+//=========================================================================
+// include/asm-ppc/redboot.h
+//   Copyright (c) 2002, 2003 Gary Thomas (<gary@mlbassoc.com>
+//   Copyright (c) 1997 Dan Malek (dmalek@jlc.net)
+
+//
+// Board specific details, as provided by RedBoot
+//
+
+/* A Board Information structure that is given to a program when
+ * RedBoot starts it up.  Note: not all fields make sense for all
+ * architectures and it's up to the platform specific code to fill
+ * in the details.
+ */
+typedef struct bd_info {
+    unsigned int   bi_tag;        /* Should be 0x42444944 "BDID" */
+    unsigned int   bi_size;       /* Size of this structure */
+    unsigned int   bi_revision;   /* revision of this structure */
+    unsigned int   bi_bdate;      /* bootstrap date, i.e. 0x19971106 */
+    unsigned int   bi_memstart;   /* Memory start address */
+    unsigned int   bi_memsize;    /* Memory (end) size in bytes */
+    unsigned int   bi_intfreq;    /* Internal Freq, in Hz */
+    unsigned int   bi_busfreq;    /* Bus Freq, in Hz */
+    unsigned int   bi_cpmfreq;    /* CPM Freq, in Hz */
+    unsigned int   bi_brgfreq;    /* BRG Freq, in Hz */
+    unsigned int   bi_vco;        /* VCO Out from PLL */
+    unsigned int   bi_pci_freq;   /* PCI Freq, in Hz */
+    unsigned int   bi_baudrate;   /* Default console baud rate */
+    unsigned int   bi_immr;       /* IMMR when called from boot rom */
+    unsigned char  bi_enetaddr[6];
+    unsigned int   bi_flashbase;  /* Physical address of FLASH memory */
+    unsigned int   bi_flashsize;  /* Length of FLASH memory */
+    int            bi_flashwidth; /* Width (8,16,32,64) */
+    unsigned char *bi_cmdline;    /* Pointer to command line */
+    unsigned char  bi_esa[3][6];  /* Ethernet station addresses */
+    unsigned int   bi_ramdisk_begin, bi_ramdisk_end;
+    struct {                      /* Information about [main] video screen */
+        short x_res;              /*   Horizontal resolution in pixels */
+        short y_res;              /*   Vertical resolution in pixels */
+        short bpp;                /*   Bits/pixel */
+        short mode;               /*   Type of pixels (packed, indexed) */
+        unsigned long fb;         /*   Pointer to frame buffer (pixel) memory */
+    } bi_video;
+    void         (*bi_cputc)(char);   /* Write a character to the RedBoot console */
+    char         (*bi_cgetc)(void);   /* Read a character from the RedBoot console */
+    int          (*bi_ctstc)(void);   /* Test for input on the RedBoot console */
+} bd_t;
+
+#define BI_REV 0x0102    /* Version 1.02 */
+
+#define bi_pci_busfreq bi_pci_freq
+#define bi_immr_base   bi_immr
+#endif