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, 136 insertions, 0 deletions

diff --git a/include/asm-generic/video.h b/include/asm-generic/video.h
new file mode 100644
index 000000000..b1da2309d
--- /dev/null
+++ b/include/asm-generic/video.h
@@ -0,0 +1,136 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __ASM_GENERIC_VIDEO_H_
+#define __ASM_GENERIC_VIDEO_H_
+
+/*
+ * Only include this header file from your architecture's <asm/fb.h>.
+ */
+
+#include <linux/io.h>
+#include <linux/mm_types.h>
+#include <linux/pgtable.h>
+#include <linux/types.h>
+
+struct device;
+
+#ifndef pgprot_framebuffer
+#define pgprot_framebuffer pgprot_framebuffer
+static inline pgprot_t pgprot_framebuffer(pgprot_t prot,
+					  unsigned long vm_start, unsigned long vm_end,
+					  unsigned long offset)
+{
+	return pgprot_writecombine(prot);
+}
+#endif
+
+#ifndef video_is_primary_device
+#define video_is_primary_device video_is_primary_device
+static inline bool video_is_primary_device(struct device *dev)
+{
+	return false;
+}
+#endif
+
+/*
+ * I/O helpers for the framebuffer. Prefer these functions over their
+ * regular counterparts. The regular I/O functions provide in-order
+ * access and swap bytes to/from little-endian ordering. Neither is
+ * required for framebuffers. Instead, the helpers read and write
+ * raw framebuffer data. Independent operations can be reordered for
+ * improved performance.
+ */
+
+#ifndef fb_readb
+static inline u8 fb_readb(const volatile void __iomem *addr)
+{
+	return __raw_readb(addr);
+}
+#define fb_readb fb_readb
+#endif
+
+#ifndef fb_readw
+static inline u16 fb_readw(const volatile void __iomem *addr)
+{
+	return __raw_readw(addr);
+}
+#define fb_readw fb_readw
+#endif
+
+#ifndef fb_readl
+static inline u32 fb_readl(const volatile void __iomem *addr)
+{
+	return __raw_readl(addr);
+}
+#define fb_readl fb_readl
+#endif
+
+#ifndef fb_readq
+#if defined(__raw_readq)
+static inline u64 fb_readq(const volatile void __iomem *addr)
+{
+	return __raw_readq(addr);
+}
+#define fb_readq fb_readq
+#endif
+#endif
+
+#ifndef fb_writeb
+static inline void fb_writeb(u8 b, volatile void __iomem *addr)
+{
+	__raw_writeb(b, addr);
+}
+#define fb_writeb fb_writeb
+#endif
+
+#ifndef fb_writew
+static inline void fb_writew(u16 b, volatile void __iomem *addr)
+{
+	__raw_writew(b, addr);
+}
+#define fb_writew fb_writew
+#endif
+
+#ifndef fb_writel
+static inline void fb_writel(u32 b, volatile void __iomem *addr)
+{
+	__raw_writel(b, addr);
+}
+#define fb_writel fb_writel
+#endif
+
+#ifndef fb_writeq
+#if defined(__raw_writeq)
+static inline void fb_writeq(u64 b, volatile void __iomem *addr)
+{
+	__raw_writeq(b, addr);
+}
+#define fb_writeq fb_writeq
+#endif
+#endif
+
+#ifndef fb_memcpy_fromio
+static inline void fb_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n)
+{
+	memcpy_fromio(to, from, n);
+}
+#define fb_memcpy_fromio fb_memcpy_fromio
+#endif
+
+#ifndef fb_memcpy_toio
+static inline void fb_memcpy_toio(volatile void __iomem *to, const void *from, size_t n)
+{
+	memcpy_toio(to, from, n);
+}
+#define fb_memcpy_toio fb_memcpy_toio
+#endif
+
+#ifndef fb_memset
+static inline void fb_memset_io(volatile void __iomem *addr, int c, size_t n)
+{
+	memset_io(addr, c, n);
+}
+#define fb_memset fb_memset_io
+#endif
+
+#endif /* __ASM_GENERIC_VIDEO_H_ */