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, 154 insertions, 0 deletions

diff --git a/include/net/inetpeer.h b/include/net/inetpeer.h
new file mode 100644
index 000000000..414e9adf4
--- /dev/null
+++ b/include/net/inetpeer.h
@@ -0,0 +1,154 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *		INETPEER - A storage for permanent information about peers
+ *
+ *  Authors:	Andrey V. Savochkin <saw@msu.ru>
+ */
+
+#ifndef _NET_INETPEER_H
+#define _NET_INETPEER_H
+
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/spinlock.h>
+#include <linux/rtnetlink.h>
+#include <net/ipv6.h>
+#include <linux/atomic.h>
+
+/* IPv4 address key for cache lookups */
+struct ipv4_addr_key {
+	__be32	addr;
+	int	vif;
+};
+
+#define INETPEER_MAXKEYSZ   (sizeof(struct in6_addr) / sizeof(u32))
+
+struct inetpeer_addr {
+	union {
+		struct ipv4_addr_key	a4;
+		struct in6_addr		a6;
+		u32			key[INETPEER_MAXKEYSZ];
+	};
+	__u16				family;
+};
+
+struct inet_peer {
+	struct rb_node		rb_node;
+	u64			hash;
+	struct inetpeer_addr	daddr;
+
+	u32			metrics[RTAX_MAX];
+	u32			rate_tokens;	/* rate limiting for ICMP */
+	u32			n_redirects;
+	unsigned long		rate_last;
+	/*
+	 * Once inet_peer is queued for deletion (refcnt == 0), following field
+	 * is not available: rid
+	 * We can share memory with rcu_head to help keep inet_peer small.
+	 */
+	union {
+		struct {
+			atomic_t			rid;		/* Frag reception counter */
+		};
+		struct rcu_head         rcu;
+	};
+
+	/* following fields might be frequently dirtied */
+	__u32			dtime;	/* the time of last use of not referenced entries */
+	refcount_t		refcnt;
+};
+
+struct inet_peer_base {
+	struct rb_root		rb_root;
+	seqlock_t		lock;
+	int			total;
+};
+
+void inet_peer_base_init(struct inet_peer_base *);
+
+void inet_initpeers(void) __init;
+
+#define INETPEER_METRICS_NEW	(~(u32) 0)
+
+static inline void inetpeer_set_addr_v4(struct inetpeer_addr *iaddr, __be32 ip)
+{
+	iaddr->a4.addr = ip;
+	iaddr->a4.vif = 0;
+	iaddr->family = AF_INET;
+}
+
+static inline __be32 inetpeer_get_addr_v4(struct inetpeer_addr *iaddr)
+{
+	return iaddr->a4.addr;
+}
+
+static inline void inetpeer_set_addr_v6(struct inetpeer_addr *iaddr,
+					struct in6_addr *in6)
+{
+	iaddr->a6 = *in6;
+	iaddr->family = AF_INET6;
+}
+
+static inline struct in6_addr *inetpeer_get_addr_v6(struct inetpeer_addr *iaddr)
+{
+	return &iaddr->a6;
+}
+
+/* can be called with or without local BH being disabled */
+struct inet_peer *inet_getpeer(struct inet_peer_base *base,
+			       const struct inetpeer_addr *daddr);
+
+static inline struct inet_peer *inet_getpeer_v4(struct inet_peer_base *base,
+						__be32 v4daddr,
+						int vif)
+{
+	struct inetpeer_addr daddr;
+
+	daddr.a4.addr = v4daddr;
+	daddr.a4.vif = vif;
+	daddr.family = AF_INET;
+	return inet_getpeer(base, &daddr);
+}
+
+static inline struct inet_peer *inet_getpeer_v6(struct inet_peer_base *base,
+						const struct in6_addr *v6daddr)
+{
+	struct inetpeer_addr daddr;
+
+	daddr.a6 = *v6daddr;
+	daddr.family = AF_INET6;
+	return inet_getpeer(base, &daddr);
+}
+
+static inline int inetpeer_addr_cmp(const struct inetpeer_addr *a,
+				    const struct inetpeer_addr *b)
+{
+	int i, n;
+
+	if (a->family != b->family)
+		return a->family < b->family ? -1 : 1;
+
+	if (a->family == AF_INET)
+		n = sizeof(a->a4) / sizeof(u32);
+	else
+		n = sizeof(a->a6) / sizeof(u32);
+
+	for (i = 0; i < n; i++) {
+		if (a->key[i] == b->key[i])
+			continue;
+		if (a->key[i] < b->key[i])
+			return -1;
+		return 1;
+	}
+
+	return 0;
+}
+
+/* can be called from BH context or outside */
+void inet_putpeer(struct inet_peer *p);
+bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout);
+
+void inetpeer_invalidate_tree(struct inet_peer_base *);
+
+#endif /* _NET_INETPEER_H */