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, 65 insertions, 0 deletions

diff --git a/include/net/hotdata.h b/include/net/hotdata.h
new file mode 100644
index 000000000..62534d1f3
--- /dev/null
+++ b/include/net/hotdata.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _NET_HOTDATA_H
+#define _NET_HOTDATA_H
+
+#include <linux/llist.h>
+#include <linux/types.h>
+#include <linux/netdevice.h>
+#include <net/protocol.h>
+#ifdef CONFIG_RPS
+#include <net/rps-types.h>
+#endif
+
+struct skb_defer_node {
+	struct llist_head	defer_list;
+	atomic_long_t		defer_count;
+} ____cacheline_aligned_in_smp;
+
+/* Read mostly data used in network fast paths. */
+struct net_hotdata {
+#if IS_ENABLED(CONFIG_INET)
+	struct packet_offload	ip_packet_offload;
+	struct net_offload	tcpv4_offload;
+	struct net_protocol	tcp_protocol;
+	struct net_offload 	udpv4_offload;
+	struct net_protocol	udp_protocol;
+	struct packet_offload	ipv6_packet_offload;
+	struct net_offload	tcpv6_offload;
+#if IS_ENABLED(CONFIG_IPV6)
+	struct inet6_protocol	tcpv6_protocol;
+	struct inet6_protocol	udpv6_protocol;
+#endif
+	struct net_offload	udpv6_offload;
+#endif
+	struct list_head	offload_base;
+	struct kmem_cache	*skbuff_cache;
+	struct kmem_cache	*skbuff_fclone_cache;
+	struct kmem_cache	*skb_small_head_cache;
+#ifdef CONFIG_RPS
+	rps_tag_ptr		rps_sock_flow_table;
+	u32			rps_cpu_mask;
+#endif
+	struct skb_defer_node __percpu *skb_defer_nodes;
+	int			gro_normal_batch;
+	int			netdev_budget;
+	int			netdev_budget_usecs;
+	int			tstamp_prequeue;
+	int			max_backlog;
+	int			qdisc_max_burst;
+	int			dev_tx_weight;
+	int			dev_rx_weight;
+	int			sysctl_max_skb_frags;
+	int			sysctl_skb_defer_max;
+	int			sysctl_mem_pcpu_rsv;
+};
+
+#define inet_ehash_secret	net_hotdata.tcp_protocol.secret
+#define udp_ehash_secret	net_hotdata.udp_protocol.secret
+#define inet6_ehash_secret	net_hotdata.tcpv6_protocol.secret
+#define tcp_ipv6_hash_secret	net_hotdata.tcpv6_offload.secret
+#define udp6_ehash_secret	net_hotdata.udpv6_protocol.secret
+#define udp_ipv6_hash_secret	net_hotdata.udpv6_offload.secret
+
+extern struct net_hotdata net_hotdata;
+
+#endif /* _NET_HOTDATA_H */