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, 311 insertions, 0 deletions

diff --git a/net/mctp/test/utils.c b/net/mctp/test/utils.c
new file mode 100644
index 000000000..6eef8d485
--- /dev/null
+++ b/net/mctp/test/utils.c
@@ -0,0 +1,311 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/netdevice.h>
+#include <linux/mctp.h>
+#include <linux/if_arp.h>
+
+#include <net/mctp.h>
+#include <net/mctpdevice.h>
+#include <net/pkt_sched.h>
+
+#include "utils.h"
+
+static netdev_tx_t mctp_test_dev_tx(struct sk_buff *skb,
+				    struct net_device *ndev)
+{
+	struct mctp_test_dev *dev = netdev_priv(ndev);
+
+	skb_queue_tail(&dev->pkts, skb);
+
+	return NETDEV_TX_OK;
+}
+
+static const struct net_device_ops mctp_test_netdev_ops = {
+	.ndo_start_xmit = mctp_test_dev_tx,
+};
+
+static void mctp_test_dev_setup(struct net_device *ndev)
+{
+	ndev->type = ARPHRD_MCTP;
+	ndev->mtu = MCTP_DEV_TEST_MTU;
+	ndev->hard_header_len = 0;
+	ndev->tx_queue_len = 0;
+	ndev->flags = IFF_NOARP;
+	ndev->netdev_ops = &mctp_test_netdev_ops;
+	ndev->needs_free_netdev = true;
+}
+
+static struct mctp_test_dev *__mctp_test_create_dev(unsigned short lladdr_len,
+						    const unsigned char *lladdr)
+{
+	struct mctp_test_dev *dev;
+	struct net_device *ndev;
+	int rc;
+
+	if (WARN_ON(lladdr_len > MAX_ADDR_LEN))
+		return NULL;
+
+	ndev = alloc_netdev(sizeof(*dev), "mctptest%d", NET_NAME_ENUM,
+			    mctp_test_dev_setup);
+	if (!ndev)
+		return NULL;
+
+	dev = netdev_priv(ndev);
+	dev->ndev = ndev;
+	ndev->addr_len = lladdr_len;
+	dev_addr_set(ndev, lladdr);
+	skb_queue_head_init(&dev->pkts);
+
+	rc = register_netdev(ndev);
+	if (rc) {
+		free_netdev(ndev);
+		return NULL;
+	}
+
+	rcu_read_lock();
+	dev->mdev = __mctp_dev_get(ndev);
+	dev->mdev->net = mctp_default_net(dev_net(ndev));
+	rcu_read_unlock();
+
+	/* bring the device up; we want to be able to TX immediately */
+	rtnl_lock();
+	dev_open(ndev, NULL);
+	rtnl_unlock();
+
+	return dev;
+}
+
+struct mctp_test_dev *mctp_test_create_dev(void)
+{
+	return __mctp_test_create_dev(0, NULL);
+}
+
+struct mctp_test_dev *mctp_test_create_dev_with_addr(mctp_eid_t addr)
+{
+	struct mctp_test_dev *dev;
+
+	dev = __mctp_test_create_dev(0, NULL);
+	if (!dev)
+		return NULL;
+
+	dev->mdev->addrs = kmalloc_objs(u8, 1, GFP_KERNEL);
+	if (!dev->mdev->addrs) {
+		mctp_test_destroy_dev(dev);
+		return NULL;
+	}
+
+	dev->mdev->num_addrs = 1;
+	dev->mdev->addrs[0] = addr;
+
+	return dev;
+}
+
+struct mctp_test_dev *mctp_test_create_dev_lladdr(unsigned short lladdr_len,
+						  const unsigned char *lladdr)
+{
+	return __mctp_test_create_dev(lladdr_len, lladdr);
+}
+
+void mctp_test_destroy_dev(struct mctp_test_dev *dev)
+{
+	skb_queue_purge(&dev->pkts);
+	mctp_dev_put(dev->mdev);
+	unregister_netdev(dev->ndev);
+}
+
+static int mctp_test_dst_output(struct mctp_dst *dst, struct sk_buff *skb)
+{
+	skb->dev = dst->dev->dev;
+	dev_direct_xmit(skb, 0);
+
+	return 0;
+}
+
+/* local version of mctp_route_alloc() */
+static struct mctp_test_route *mctp_route_test_alloc(void)
+{
+	struct mctp_test_route *rt;
+
+	rt = kzalloc_obj(*rt);
+	if (!rt)
+		return NULL;
+
+	INIT_LIST_HEAD(&rt->rt.list);
+	refcount_set(&rt->rt.refs, 1);
+	rt->rt.output = mctp_test_dst_output;
+
+	return rt;
+}
+
+struct mctp_test_route *mctp_test_create_route_direct(struct net *net,
+						      struct mctp_dev *dev,
+						      mctp_eid_t eid,
+						      unsigned int mtu)
+{
+	struct mctp_test_route *rt;
+
+	rt = mctp_route_test_alloc();
+	if (!rt)
+		return NULL;
+
+	rt->rt.min = eid;
+	rt->rt.max = eid;
+	rt->rt.mtu = mtu;
+	rt->rt.type = RTN_UNSPEC;
+	rt->rt.dst_type = MCTP_ROUTE_DIRECT;
+	if (dev)
+		mctp_dev_hold(dev);
+	rt->rt.dev = dev;
+
+	list_add_rcu(&rt->rt.list, &net->mctp.routes);
+
+	return rt;
+}
+
+struct mctp_test_route *mctp_test_create_route_gw(struct net *net,
+						  unsigned int netid,
+						  mctp_eid_t eid,
+						  mctp_eid_t gw,
+						  unsigned int mtu)
+{
+	struct mctp_test_route *rt;
+
+	rt = mctp_route_test_alloc();
+	if (!rt)
+		return NULL;
+
+	rt->rt.min = eid;
+	rt->rt.max = eid;
+	rt->rt.mtu = mtu;
+	rt->rt.type = RTN_UNSPEC;
+	rt->rt.dst_type = MCTP_ROUTE_GATEWAY;
+	rt->rt.gateway.eid = gw;
+	rt->rt.gateway.net = netid;
+
+	list_add_rcu(&rt->rt.list, &net->mctp.routes);
+
+	return rt;
+}
+
+/* Convenience function for our test dst; release with mctp_dst_release() */
+void mctp_test_dst_setup(struct kunit *test, struct mctp_dst *dst,
+			 struct mctp_test_dev *dev, unsigned int mtu)
+{
+	unsigned long flags;
+
+	KUNIT_EXPECT_NOT_ERR_OR_NULL(test, dev);
+
+	memset(dst, 0, sizeof(*dst));
+
+	dst->dev = dev->mdev;
+	__mctp_dev_get(dst->dev->dev);
+	dst->mtu = mtu;
+	dst->output = mctp_test_dst_output;
+	dst->saddr = MCTP_ADDR_NULL;
+	spin_lock_irqsave(&dev->mdev->addrs_lock, flags);
+	if (dev->mdev->num_addrs)
+		dst->saddr = dev->mdev->addrs[0];
+	spin_unlock_irqrestore(&dev->mdev->addrs_lock, flags);
+}
+
+void mctp_test_route_destroy(struct kunit *test, struct mctp_test_route *rt)
+{
+	unsigned int refs;
+
+	rtnl_lock();
+	list_del_rcu(&rt->rt.list);
+	rtnl_unlock();
+
+	if (rt->rt.dst_type == MCTP_ROUTE_DIRECT && rt->rt.dev)
+		mctp_dev_put(rt->rt.dev);
+
+	refs = refcount_read(&rt->rt.refs);
+	KUNIT_ASSERT_EQ_MSG(test, refs, 1, "route ref imbalance");
+
+	kfree_rcu(&rt->rt, rcu);
+}
+
+void mctp_test_skb_set_dev(struct sk_buff *skb, struct mctp_test_dev *dev)
+{
+	struct mctp_skb_cb *cb;
+
+	cb = mctp_cb(skb);
+	cb->net = READ_ONCE(dev->mdev->net);
+	skb->dev = dev->ndev;
+}
+
+struct sk_buff *mctp_test_create_skb(const struct mctp_hdr *hdr,
+				     unsigned int data_len)
+{
+	size_t hdr_len = sizeof(*hdr);
+	struct sk_buff *skb;
+	unsigned int i;
+	u8 *buf;
+
+	skb = alloc_skb(hdr_len + data_len, GFP_KERNEL);
+	if (!skb)
+		return NULL;
+
+	__mctp_cb(skb);
+	memcpy(skb_put(skb, hdr_len), hdr, hdr_len);
+
+	buf = skb_put(skb, data_len);
+	for (i = 0; i < data_len; i++)
+		buf[i] = i & 0xff;
+
+	return skb;
+}
+
+struct sk_buff *__mctp_test_create_skb_data(const struct mctp_hdr *hdr,
+					    const void *data, size_t data_len)
+{
+	size_t hdr_len = sizeof(*hdr);
+	struct sk_buff *skb;
+
+	skb = alloc_skb(hdr_len + data_len, GFP_KERNEL);
+	if (!skb)
+		return NULL;
+
+	__mctp_cb(skb);
+	memcpy(skb_put(skb, hdr_len), hdr, hdr_len);
+	memcpy(skb_put(skb, data_len), data, data_len);
+
+	return skb;
+}
+
+void mctp_test_bind_run(struct kunit *test,
+			const struct mctp_test_bind_setup *setup,
+			int *ret_bind_errno, struct socket **sock)
+{
+	struct sockaddr_mctp addr;
+	int rc;
+
+	*ret_bind_errno = -EIO;
+
+	rc = sock_create_kern(&init_net, AF_MCTP, SOCK_DGRAM, 0, sock);
+	KUNIT_ASSERT_EQ(test, rc, 0);
+
+	/* connect() if requested */
+	if (setup->have_peer) {
+		memset(&addr, 0x0, sizeof(addr));
+		addr.smctp_family = AF_MCTP;
+		addr.smctp_network = setup->peer_net;
+		addr.smctp_addr.s_addr = setup->peer_addr;
+		/* connect() type must match bind() type */
+		addr.smctp_type = setup->bind_type;
+		rc = kernel_connect(*sock, (struct sockaddr_unsized *)&addr,
+				    sizeof(addr), 0);
+		KUNIT_EXPECT_EQ(test, rc, 0);
+	}
+
+	/* bind() */
+	memset(&addr, 0x0, sizeof(addr));
+	addr.smctp_family = AF_MCTP;
+	addr.smctp_network = setup->bind_net;
+	addr.smctp_addr.s_addr = setup->bind_addr;
+	addr.smctp_type = setup->bind_type;
+
+	*ret_bind_errno =
+		kernel_bind(*sock, (struct sockaddr_unsized *)&addr,
+			    sizeof(addr));
+}