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, 124 insertions, 0 deletions

diff --git a/include/trace/events/timestamp.h b/include/trace/events/timestamp.h
new file mode 100644
index 000000000..d6503612d
--- /dev/null
+++ b/include/trace/events/timestamp.h
@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM timestamp
+
+#if !defined(_TRACE_TIMESTAMP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_TIMESTAMP_H
+
+#include <linux/tracepoint.h>
+#include <linux/fs.h>
+
+#define CTIME_QUERIED_FLAGS \
+	{ I_CTIME_QUERIED, "Q" }
+
+DECLARE_EVENT_CLASS(ctime,
+	TP_PROTO(struct inode *inode,
+		 struct timespec64 *ctime),
+
+	TP_ARGS(inode, ctime),
+
+	TP_STRUCT__entry(
+		__field(u64,		ino)
+		__field(time64_t,	ctime_s)
+		__field(dev_t,		dev)
+		__field(u32,		ctime_ns)
+		__field(u32,		gen)
+	),
+
+	TP_fast_assign(
+		__entry->dev		= inode->i_sb->s_dev;
+		__entry->ino		= inode->i_ino;
+		__entry->gen		= inode->i_generation;
+		__entry->ctime_s	= ctime->tv_sec;
+		__entry->ctime_ns	= ctime->tv_nsec;
+	),
+
+	TP_printk("ino=%d:%d:%llu:%u ctime=%lld.%u",
+		MAJOR(__entry->dev), MINOR(__entry->dev), __entry->ino, __entry->gen,
+		__entry->ctime_s, __entry->ctime_ns
+	)
+);
+
+DEFINE_EVENT(ctime, inode_set_ctime_to_ts,
+		TP_PROTO(struct inode *inode,
+			 struct timespec64 *ctime),
+		TP_ARGS(inode, ctime));
+
+DEFINE_EVENT(ctime, ctime_xchg_skip,
+		TP_PROTO(struct inode *inode,
+			 struct timespec64 *ctime),
+		TP_ARGS(inode, ctime));
+
+TRACE_EVENT(ctime_ns_xchg,
+	TP_PROTO(struct inode *inode,
+		 u32 old,
+		 u32 new,
+		 u32 cur),
+
+	TP_ARGS(inode, old, new, cur),
+
+	TP_STRUCT__entry(
+		__field(u64,		ino)
+		__field(dev_t,		dev)
+		__field(u32,		gen)
+		__field(u32,		old)
+		__field(u32,		new)
+		__field(u32,		cur)
+	),
+
+	TP_fast_assign(
+		__entry->dev		= inode->i_sb->s_dev;
+		__entry->ino		= inode->i_ino;
+		__entry->gen		= inode->i_generation;
+		__entry->old		= old;
+		__entry->new		= new;
+		__entry->cur		= cur;
+	),
+
+	TP_printk("ino=%d:%d:%llu:%u old=%u:%s new=%u cur=%u:%s",
+		MAJOR(__entry->dev), MINOR(__entry->dev), __entry->ino, __entry->gen,
+		__entry->old & ~I_CTIME_QUERIED,
+		__print_flags(__entry->old & I_CTIME_QUERIED, "|", CTIME_QUERIED_FLAGS),
+		__entry->new,
+		__entry->cur & ~I_CTIME_QUERIED,
+		__print_flags(__entry->cur & I_CTIME_QUERIED, "|", CTIME_QUERIED_FLAGS)
+	)
+);
+
+TRACE_EVENT(fill_mg_cmtime,
+	TP_PROTO(struct inode *inode,
+		 struct timespec64 *ctime,
+		 struct timespec64 *mtime),
+
+	TP_ARGS(inode, ctime, mtime),
+
+	TP_STRUCT__entry(
+		__field(u64,		ino)
+		__field(time64_t,	ctime_s)
+		__field(time64_t,	mtime_s)
+		__field(dev_t,		dev)
+		__field(u32,		ctime_ns)
+		__field(u32,		mtime_ns)
+		__field(u32,		gen)
+	),
+
+	TP_fast_assign(
+		__entry->dev		= inode->i_sb->s_dev;
+		__entry->ino		= inode->i_ino;
+		__entry->gen		= inode->i_generation;
+		__entry->ctime_s	= ctime->tv_sec;
+		__entry->mtime_s	= mtime->tv_sec;
+		__entry->ctime_ns	= ctime->tv_nsec;
+		__entry->mtime_ns	= mtime->tv_nsec;
+	),
+
+	TP_printk("ino=%d:%d:%llu:%u ctime=%lld.%u mtime=%lld.%u",
+		MAJOR(__entry->dev), MINOR(__entry->dev), __entry->ino, __entry->gen,
+		__entry->ctime_s, __entry->ctime_ns,
+		__entry->mtime_s, __entry->mtime_ns
+	)
+);
+#endif /* _TRACE_TIMESTAMP_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>