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, 56 insertions, 0 deletions

diff --git a/include/net/psample.h b/include/net/psample.h
new file mode 100644
index 000000000..5071b5fc2
--- /dev/null
+++ b/include/net/psample.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NET_PSAMPLE_H
+#define __NET_PSAMPLE_H
+
+#include <uapi/linux/psample.h>
+#include <linux/list.h>
+
+struct psample_group {
+	struct list_head list;
+	struct net *net;
+	u32 group_num;
+	u32 refcount;
+	u32 seq;
+	struct rcu_head rcu;
+};
+
+struct psample_metadata {
+	u32 trunc_size;
+	int in_ifindex;
+	int out_ifindex;
+	u16 out_tc;
+	u64 out_tc_occ;	/* bytes */
+	u64 latency;	/* nanoseconds */
+	u8 out_tc_valid:1,
+	   out_tc_occ_valid:1,
+	   latency_valid:1,
+	   rate_as_probability:1,
+	   unused:4;
+	const u8 *user_cookie;
+	u32 user_cookie_len;
+};
+
+struct psample_group *psample_group_get(struct net *net, u32 group_num);
+void psample_group_take(struct psample_group *group);
+void psample_group_put(struct psample_group *group);
+
+struct sk_buff;
+
+#if IS_ENABLED(CONFIG_PSAMPLE)
+
+void psample_sample_packet(struct psample_group *group,
+			   const struct sk_buff *skb, u32 sample_rate,
+			   const struct psample_metadata *md);
+
+#else
+
+static inline void psample_sample_packet(struct psample_group *group,
+					 const struct sk_buff *skb,
+					 u32 sample_rate,
+					 const struct psample_metadata *md)
+{
+}
+
+#endif
+
+#endif /* __NET_PSAMPLE_H */