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, 151 insertions, 0 deletions

diff --git a/net/llc/llc_if.c b/net/llc/llc_if.c
new file mode 100644
index 000000000..1514362e6
--- /dev/null
+++ b/net/llc/llc_if.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * llc_if.c - Defines LLC interface to upper layer
+ *
+ * Copyright (c) 1997 by Procom Technology, Inc.
+ * 		 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
+ */
+#include <linux/gfp.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/errno.h>
+#include <net/llc_if.h>
+#include <net/llc_sap.h>
+#include <net/llc_s_ev.h>
+#include <net/llc_conn.h>
+#include <net/sock.h>
+#include <net/llc_c_ev.h>
+#include <net/llc_c_ac.h>
+#include <net/llc_c_st.h>
+#include <net/tcp_states.h>
+
+/**
+ *	llc_build_and_send_pkt - Connection data sending for upper layers.
+ *	@sk: connection
+ *	@skb: packet to send
+ *
+ *	This function is called when upper layer wants to send data using
+ *	connection oriented communication mode. During sending data, connection
+ *	will be locked and received frames and expired timers will be queued.
+ *	Returns 0 for success, -ECONNABORTED when the connection already
+ *	closed and -EBUSY when sending data is not permitted in this state or
+ *	LLC has send an I pdu with p bit set to 1 and is waiting for it's
+ *	response.
+ *
+ *	This function always consumes a reference to the skb.
+ */
+int llc_build_and_send_pkt(struct sock *sk, struct sk_buff *skb)
+{
+	struct llc_conn_state_ev *ev;
+	int rc = -ECONNABORTED;
+	struct llc_sock *llc = llc_sk(sk);
+
+	if (unlikely(llc->state == LLC_CONN_STATE_ADM))
+		goto out_free;
+	rc = -EBUSY;
+	if (unlikely(llc_data_accept_state(llc->state) || /* data_conn_refuse */
+		     llc->p_flag)) {
+		llc->failed_data_req = 1;
+		goto out_free;
+	}
+	ev = llc_conn_ev(skb);
+	ev->type      = LLC_CONN_EV_TYPE_PRIM;
+	ev->prim      = LLC_DATA_PRIM;
+	ev->prim_type = LLC_PRIM_TYPE_REQ;
+	skb->dev      = llc->dev;
+	return llc_conn_state_process(sk, skb);
+
+out_free:
+	kfree_skb(skb);
+	return rc;
+}
+
+/**
+ *	llc_establish_connection - Called by upper layer to establish a conn
+ *	@sk: connection
+ *	@lmac: local mac address
+ *	@dmac: destination mac address
+ *	@dsap: destination sap
+ *
+ *	Upper layer calls this to establish an LLC connection with a remote
+ *	machine. This function packages a proper event and sends it connection
+ *	component state machine. Success or failure of connection
+ *	establishment will inform to upper layer via calling it's confirm
+ *	function and passing proper information.
+ */
+int llc_establish_connection(struct sock *sk, const u8 *lmac, u8 *dmac, u8 dsap)
+{
+	int rc = -EISCONN;
+	struct llc_addr laddr, daddr;
+	struct sk_buff *skb;
+	struct llc_sock *llc = llc_sk(sk);
+	struct sock *existing;
+
+	laddr.lsap = llc->sap->laddr.lsap;
+	daddr.lsap = dsap;
+	memcpy(daddr.mac, dmac, sizeof(daddr.mac));
+	memcpy(laddr.mac, lmac, sizeof(laddr.mac));
+	existing = llc_lookup_established(llc->sap, &daddr, &laddr, sock_net(sk));
+	if (existing) {
+		if (existing->sk_state == TCP_ESTABLISHED) {
+			sk = existing;
+			goto out_put;
+		} else
+			sock_put(existing);
+	}
+	sock_hold(sk);
+	rc = -ENOMEM;
+	skb = alloc_skb(0, GFP_ATOMIC);
+	if (skb) {
+		struct llc_conn_state_ev *ev = llc_conn_ev(skb);
+
+		ev->type      = LLC_CONN_EV_TYPE_PRIM;
+		ev->prim      = LLC_CONN_PRIM;
+		ev->prim_type = LLC_PRIM_TYPE_REQ;
+		skb_set_owner_w(skb, sk);
+		rc = llc_conn_state_process(sk, skb);
+	}
+out_put:
+	sock_put(sk);
+	return rc;
+}
+
+/**
+ *	llc_send_disc - Called by upper layer to close a connection
+ *	@sk: connection to be closed
+ *
+ *	Upper layer calls this when it wants to close an established LLC
+ *	connection with a remote machine. This function packages a proper event
+ *	and sends it to connection component state machine. Returns 0 for
+ *	success, 1 otherwise.
+ */
+int llc_send_disc(struct sock *sk)
+{
+	u16 rc = 1;
+	struct llc_conn_state_ev *ev;
+	struct sk_buff *skb;
+
+	sock_hold(sk);
+	if (sk->sk_type != SOCK_STREAM || sk->sk_state != TCP_ESTABLISHED ||
+	    llc_sk(sk)->state == LLC_CONN_STATE_ADM ||
+	    llc_sk(sk)->state == LLC_CONN_OUT_OF_SVC)
+		goto out;
+	/*
+	 * Postpone unassigning the connection from its SAP and returning the
+	 * connection until all ACTIONs have been completely executed
+	 */
+	skb = alloc_skb(0, GFP_ATOMIC);
+	if (!skb)
+		goto out;
+	skb_set_owner_w(skb, sk);
+	sk->sk_state  = TCP_CLOSING;
+	ev	      = llc_conn_ev(skb);
+	ev->type      = LLC_CONN_EV_TYPE_PRIM;
+	ev->prim      = LLC_DISC_PRIM;
+	ev->prim_type = LLC_PRIM_TYPE_REQ;
+	rc = llc_conn_state_process(sk, skb);
+out:
+	sock_put(sk);
+	return rc;
+}