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, 43 insertions, 0 deletions

diff --git a/net/batman-adv/mesh-interface.h b/net/batman-adv/mesh-interface.h
new file mode 100644
index 000000000..5e1e83e04
--- /dev/null
+++ b/net/batman-adv/mesh-interface.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) B.A.T.M.A.N. contributors:
+ *
+ * Marek Lindner
+ */
+
+#ifndef _NET_BATMAN_ADV_MESH_INTERFACE_H_
+#define _NET_BATMAN_ADV_MESH_INTERFACE_H_
+
+#include "main.h"
+
+#include <linux/kref.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/types.h>
+
+int batadv_skb_head_push(struct sk_buff *skb, unsigned int len);
+void batadv_interface_rx(struct net_device *mesh_iface,
+			 struct sk_buff *skb, int hdr_size,
+			 struct batadv_orig_node *orig_node);
+bool batadv_meshif_is_valid(const struct net_device *net_dev);
+extern struct rtnl_link_ops batadv_link_ops;
+int batadv_meshif_create_vlan(struct batadv_priv *bat_priv, unsigned short vid);
+void batadv_meshif_destroy_vlan(struct batadv_priv *bat_priv,
+				struct batadv_meshif_vlan *vlan);
+void batadv_meshif_vlan_release(struct kref *ref);
+struct batadv_meshif_vlan *batadv_meshif_vlan_get(struct batadv_priv *bat_priv,
+						  unsigned short vid);
+
+/**
+ * batadv_meshif_vlan_put() - decrease the vlan object refcounter and
+ *  possibly release it
+ * @vlan: the vlan object to release
+ */
+static inline void batadv_meshif_vlan_put(struct batadv_meshif_vlan *vlan)
+{
+	if (!vlan)
+		return;
+
+	kref_put(&vlan->refcount, batadv_meshif_vlan_release);
+}
+
+#endif /* _NET_BATMAN_ADV_MESH_INTERFACE_H_ */