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, 161 insertions, 0 deletions

diff --git a/rust/helpers/io.c b/rust/helpers/io.c
new file mode 100644
index 000000000..308950aae
--- /dev/null
+++ b/rust/helpers/io.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/io.h>
+#include <linux/ioport.h>
+
+#ifdef CONFIG_HAS_IOMEM
+__rust_helper void __iomem *rust_helper_ioremap(phys_addr_t offset, size_t size)
+{
+	return ioremap(offset, size);
+}
+
+__rust_helper void __iomem *rust_helper_ioremap_np(phys_addr_t offset,
+						   size_t size)
+{
+	return ioremap_np(offset, size);
+}
+
+__rust_helper void rust_helper_iounmap(void __iomem *addr)
+{
+	iounmap(addr);
+}
+#endif /* CONFIG_HAS_IOMEM */
+
+__rust_helper void rust_helper_memcpy_fromio(void *dst,
+					     const volatile void __iomem *src,
+					     size_t count)
+{
+	memcpy_fromio(dst, src, count);
+}
+
+__rust_helper void rust_helper_memcpy_toio(volatile void __iomem *dst,
+					   const void *src, size_t count)
+{
+	memcpy_toio(dst, src, count);
+}
+
+__rust_helper u8 rust_helper_readb(const void __iomem *addr)
+{
+	return readb(addr);
+}
+
+__rust_helper u16 rust_helper_readw(const void __iomem *addr)
+{
+	return readw(addr);
+}
+
+__rust_helper u32 rust_helper_readl(const void __iomem *addr)
+{
+	return readl(addr);
+}
+
+#ifdef CONFIG_64BIT
+__rust_helper u64 rust_helper_readq(const void __iomem *addr)
+{
+	return readq(addr);
+}
+#endif
+
+__rust_helper void rust_helper_writeb(u8 value, void __iomem *addr)
+{
+	writeb(value, addr);
+}
+
+__rust_helper void rust_helper_writew(u16 value, void __iomem *addr)
+{
+	writew(value, addr);
+}
+
+__rust_helper void rust_helper_writel(u32 value, void __iomem *addr)
+{
+	writel(value, addr);
+}
+
+#ifdef CONFIG_64BIT
+__rust_helper void rust_helper_writeq(u64 value, void __iomem *addr)
+{
+	writeq(value, addr);
+}
+#endif
+
+__rust_helper u8 rust_helper_readb_relaxed(const void __iomem *addr)
+{
+	return readb_relaxed(addr);
+}
+
+__rust_helper u16 rust_helper_readw_relaxed(const void __iomem *addr)
+{
+	return readw_relaxed(addr);
+}
+
+__rust_helper u32 rust_helper_readl_relaxed(const void __iomem *addr)
+{
+	return readl_relaxed(addr);
+}
+
+#ifdef CONFIG_64BIT
+__rust_helper u64 rust_helper_readq_relaxed(const void __iomem *addr)
+{
+	return readq_relaxed(addr);
+}
+#endif
+
+__rust_helper void rust_helper_writeb_relaxed(u8 value, void __iomem *addr)
+{
+	writeb_relaxed(value, addr);
+}
+
+__rust_helper void rust_helper_writew_relaxed(u16 value, void __iomem *addr)
+{
+	writew_relaxed(value, addr);
+}
+
+__rust_helper void rust_helper_writel_relaxed(u32 value, void __iomem *addr)
+{
+	writel_relaxed(value, addr);
+}
+
+#ifdef CONFIG_64BIT
+__rust_helper void rust_helper_writeq_relaxed(u64 value, void __iomem *addr)
+{
+	writeq_relaxed(value, addr);
+}
+#endif
+
+__rust_helper resource_size_t rust_helper_resource_size(struct resource *res)
+{
+	return resource_size(res);
+}
+
+__rust_helper struct resource *
+rust_helper_request_mem_region(resource_size_t start, resource_size_t n,
+			       const char *name)
+{
+	return request_mem_region(start, n, name);
+}
+
+__rust_helper void rust_helper_release_mem_region(resource_size_t start,
+						  resource_size_t n)
+{
+	release_mem_region(start, n);
+}
+
+__rust_helper struct resource *rust_helper_request_region(resource_size_t start,
+							  resource_size_t n,
+							  const char *name)
+{
+	return request_region(start, n, name);
+}
+
+__rust_helper struct resource *
+rust_helper_request_muxed_region(resource_size_t start, resource_size_t n,
+				 const char *name)
+{
+	return request_muxed_region(start, n, name);
+}
+
+__rust_helper void rust_helper_release_region(resource_size_t start,
+					      resource_size_t n)
+{
+	release_region(start, n);
+}