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, 62 insertions, 0 deletions

diff --git a/samples/bpf/sockex2_user.c b/samples/bpf/sockex2_user.c
new file mode 100644
index 000000000..2c1847133
--- /dev/null
+++ b/samples/bpf/sockex2_user.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <stdio.h>
+#include <assert.h>
+#include <linux/bpf.h>
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+#include "sock_example.h"
+#include <unistd.h>
+#include <arpa/inet.h>
+
+struct pair {
+	__u64 packets;
+	__u64 bytes;
+};
+
+int main(int ac, char **argv)
+{
+	struct bpf_program *prog;
+	struct bpf_object *obj;
+	int map_fd, prog_fd;
+	char filename[256];
+	int i, sock, err;
+	FILE *f;
+
+	snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+	obj = bpf_object__open_file(filename, NULL);
+	if (libbpf_get_error(obj))
+		return 1;
+
+	prog = bpf_object__next_program(obj, NULL);
+	bpf_program__set_type(prog, BPF_PROG_TYPE_SOCKET_FILTER);
+
+	err = bpf_object__load(obj);
+	if (err)
+		return 1;
+
+	prog_fd = bpf_program__fd(prog);
+	map_fd = bpf_object__find_map_fd_by_name(obj, "hash_map");
+
+	sock = open_raw_sock("lo");
+
+	assert(setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd,
+			  sizeof(prog_fd)) == 0);
+
+	f = popen("ping -4 -c5 localhost", "r");
+	(void) f;
+
+	for (i = 0; i < 5; i++) {
+		int key = 0, next_key;
+		struct pair value;
+
+		while (bpf_map_get_next_key(map_fd, &key, &next_key) == 0) {
+			bpf_map_lookup_elem(map_fd, &next_key, &value);
+			printf("ip %s bytes %lld packets %lld\n",
+			       inet_ntoa((struct in_addr){htonl(next_key)}),
+			       value.bytes, value.packets);
+			key = next_key;
+		}
+		sleep(1);
+	}
+	return 0;
+}