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, 77 insertions, 0 deletions

diff --git a/include/trace/events/napi.h b/include/trace/events/napi.h
new file mode 100644
index 000000000..b567b9ffe
--- /dev/null
+++ b/include/trace/events/napi.h
@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM napi
+
+#if !defined(_TRACE_NAPI_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_NAPI_H
+
+#include <linux/netdevice.h>
+#include <linux/tracepoint.h>
+#include <linux/ftrace.h>
+
+#define NO_DEV "(no_device)"
+
+TRACE_EVENT(napi_poll,
+
+	TP_PROTO(struct napi_struct *napi, int work, int budget),
+
+	TP_ARGS(napi, work, budget),
+
+	TP_STRUCT__entry(
+		__field(	struct napi_struct *,	napi)
+		__string(	dev_name, napi->dev ? napi->dev->name : NO_DEV)
+		__field(	int,			work)
+		__field(	int,			budget)
+	),
+
+	TP_fast_assign(
+		__entry->napi = napi;
+		__assign_str(dev_name);
+		__entry->work = work;
+		__entry->budget = budget;
+	),
+
+	TP_printk("napi poll on napi struct %p for device %s work %d budget %d",
+		  __entry->napi, __get_str(dev_name),
+		  __entry->work, __entry->budget)
+);
+
+TRACE_EVENT(dql_stall_detected,
+
+	TP_PROTO(unsigned short thrs, unsigned int len,
+		 unsigned long last_reap, unsigned long hist_head,
+		 unsigned long now, unsigned long *hist),
+
+	TP_ARGS(thrs, len, last_reap, hist_head, now, hist),
+
+	TP_STRUCT__entry(
+		__field(	unsigned short,		thrs)
+		__field(	unsigned int,		len)
+		__field(	unsigned long,		last_reap)
+		__field(	unsigned long,		hist_head)
+		__field(	unsigned long,		now)
+		__array(	unsigned long,		hist, 4)
+	),
+
+	TP_fast_assign(
+		__entry->thrs = thrs;
+		__entry->len = len;
+		__entry->last_reap = last_reap;
+		__entry->hist_head = hist_head * BITS_PER_LONG;
+		__entry->now = now;
+		memcpy(__entry->hist, hist, sizeof(entry->hist));
+	),
+
+	TP_printk("thrs %u  len %u  last_reap %lu  hist_head %lu  now %lu  hist %016lx %016lx %016lx %016lx",
+		  __entry->thrs, __entry->len,
+		  __entry->last_reap, __entry->hist_head, __entry->now,
+		  __entry->hist[0], __entry->hist[1],
+		  __entry->hist[2], __entry->hist[3])
+);
+
+#undef NO_DEV
+
+#endif /* _TRACE_NAPI_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>