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, 93 insertions, 0 deletions

diff --git a/include/uapi/asm-generic/signal-defs.h b/include/uapi/asm-generic/signal-defs.h
new file mode 100644
index 000000000..7572f2f46
--- /dev/null
+++ b/include/uapi/asm-generic/signal-defs.h
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef __ASM_GENERIC_SIGNAL_DEFS_H
+#define __ASM_GENERIC_SIGNAL_DEFS_H
+
+#include <linux/compiler.h>
+
+/*
+ * SA_FLAGS values:
+ *
+ * SA_NOCLDSTOP flag to turn off SIGCHLD when children stop.
+ * SA_NOCLDWAIT flag on SIGCHLD to inhibit zombies.
+ * SA_SIGINFO delivers the signal with SIGINFO structs.
+ * SA_ONSTACK indicates that a registered stack_t will be used.
+ * SA_RESTART flag to get restarting signals (which were the default long ago)
+ * SA_NODEFER prevents the current signal from being masked in the handler.
+ * SA_RESETHAND clears the handler when the signal is delivered.
+ * SA_UNSUPPORTED is a flag bit that will never be supported. Kernels from
+ * before the introduction of SA_UNSUPPORTED did not clear unknown bits from
+ * sa_flags when read using the oldact argument to sigaction and rt_sigaction,
+ * so this bit allows flag bit support to be detected from userspace while
+ * allowing an old kernel to be distinguished from a kernel that supports every
+ * flag bit.
+ * SA_EXPOSE_TAGBITS exposes an architecture-defined set of tag bits in
+ * siginfo.si_addr.
+ *
+ * SA_ONESHOT and SA_NOMASK are the historical Linux names for the Single
+ * Unix names RESETHAND and NODEFER respectively.
+ */
+#ifndef SA_NOCLDSTOP
+#define SA_NOCLDSTOP	0x00000001
+#endif
+#ifndef SA_NOCLDWAIT
+#define SA_NOCLDWAIT	0x00000002
+#endif
+#ifndef SA_SIGINFO
+#define SA_SIGINFO	0x00000004
+#endif
+/* 0x00000008 used on alpha, mips, parisc */
+/* 0x00000010 used on alpha, parisc */
+/* 0x00000020 used on alpha, parisc, sparc */
+/* 0x00000040 used on alpha, parisc */
+/* 0x00000080 used on parisc */
+/* 0x00000100 used on sparc */
+/* 0x00000200 used on sparc */
+#define SA_UNSUPPORTED	0x00000400
+#define SA_EXPOSE_TAGBITS	0x00000800
+/* 0x00010000 used on mips */
+/* 0x00800000 used for internal SA_IMMUTABLE */
+/* 0x01000000 used on x86 */
+/* 0x02000000 used on x86 */
+/*
+ * New architectures should not define the obsolete
+ *	SA_RESTORER	0x04000000
+ */
+#ifndef SA_ONSTACK
+#define SA_ONSTACK	0x08000000
+#endif
+#ifndef SA_RESTART
+#define SA_RESTART	0x10000000
+#endif
+#ifndef SA_NODEFER
+#define SA_NODEFER	0x40000000
+#endif
+#ifndef SA_RESETHAND
+#define SA_RESETHAND	0x80000000
+#endif
+
+#define SA_NOMASK	SA_NODEFER
+#define SA_ONESHOT	SA_RESETHAND
+
+#ifndef SIG_BLOCK
+#define SIG_BLOCK          0	/* for blocking signals */
+#endif
+#ifndef SIG_UNBLOCK
+#define SIG_UNBLOCK        1	/* for unblocking signals */
+#endif
+#ifndef SIG_SETMASK
+#define SIG_SETMASK        2	/* for setting the signal mask */
+#endif
+
+#ifndef __ASSEMBLY__
+typedef void __signalfn_t(int);
+typedef __signalfn_t __user *__sighandler_t;
+
+typedef void __restorefn_t(void);
+typedef __restorefn_t __user *__sigrestore_t;
+
+#define SIG_DFL	((__force __sighandler_t)0)	/* default signal handling */
+#define SIG_IGN	((__force __sighandler_t)1)	/* ignore signal */
+#define SIG_ERR	((__force __sighandler_t)-1)	/* error return from signal */
+#endif
+
+#endif /* __ASM_GENERIC_SIGNAL_DEFS_H */