ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

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;
+}