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, 71 insertions, 0 deletions

diff --git a/net/dsa/user.h b/net/dsa/user.h
new file mode 100644
index 000000000..016884bea
--- /dev/null
+++ b/net/dsa/user.h
@@ -0,0 +1,71 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef __DSA_USER_H
+#define __DSA_USER_H
+
+#include <linux/if_bridge.h>
+#include <linux/if_vlan.h>
+#include <linux/list.h>
+#include <linux/netpoll.h>
+#include <linux/types.h>
+#include <net/dsa.h>
+#include <net/gro_cells.h>
+
+struct net_device;
+struct netlink_ext_ack;
+
+extern struct notifier_block dsa_user_switchdev_notifier;
+extern struct notifier_block dsa_user_switchdev_blocking_notifier;
+
+struct dsa_user_priv {
+	/* Copy of CPU port xmit for faster access in user transmit hot path */
+	struct sk_buff *	(*xmit)(struct sk_buff *skb,
+					struct net_device *dev);
+
+	struct gro_cells	gcells;
+
+	/* DSA port data, such as switch, port index, etc. */
+	struct dsa_port		*dp;
+
+#ifdef CONFIG_NET_POLL_CONTROLLER
+	struct netpoll		*netpoll;
+#endif
+
+	/* TC context */
+	struct list_head	mall_tc_list;
+};
+
+void dsa_user_mii_bus_init(struct dsa_switch *ds);
+int dsa_user_create(struct dsa_port *dp);
+void dsa_user_destroy(struct net_device *user_dev);
+int dsa_user_suspend(struct net_device *user_dev);
+int dsa_user_resume(struct net_device *user_dev);
+int dsa_user_register_notifier(void);
+void dsa_user_unregister_notifier(void);
+int dsa_user_host_uc_install(struct net_device *dev, const u8 *addr);
+void dsa_user_host_uc_uninstall(struct net_device *dev);
+void dsa_user_sync_ha(struct net_device *dev);
+void dsa_user_unsync_ha(struct net_device *dev);
+void dsa_user_setup_tagger(struct net_device *user);
+int dsa_user_change_mtu(struct net_device *dev, int new_mtu);
+int dsa_user_change_conduit(struct net_device *dev, struct net_device *conduit,
+			    struct netlink_ext_ack *extack);
+int dsa_user_manage_vlan_filtering(struct net_device *dev,
+				   bool vlan_filtering);
+
+static inline struct dsa_port *dsa_user_to_port(const struct net_device *dev)
+{
+	struct dsa_user_priv *p = netdev_priv(dev);
+
+	return p->dp;
+}
+
+static inline struct net_device *
+dsa_user_to_conduit(const struct net_device *dev)
+{
+	struct dsa_port *dp = dsa_user_to_port(dev);
+
+	return dsa_port_to_conduit(dp);
+}
+
+#endif