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, 281 insertions, 0 deletions

diff --git a/net/8021q/vlanproc.c b/net/8021q/vlanproc.c
new file mode 100644
index 000000000..0e424e089
--- /dev/null
+++ b/net/8021q/vlanproc.c
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/******************************************************************************
+ * vlanproc.c	VLAN Module. /proc filesystem interface.
+ *
+ *		This module is completely hardware-independent and provides
+ *		access to the router using Linux /proc filesystem.
+ *
+ * Author:	Ben Greear, <greearb@candelatech.com> coppied from wanproc.c
+ *               by: Gene Kozin	<genek@compuserve.com>
+ *
+ * Copyright:	(c) 1998 Ben Greear
+ *
+ * ============================================================================
+ * Jan 20, 1998        Ben Greear     Initial Version
+ *****************************************************************************/
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/fs.h>
+#include <linux/netdevice.h>
+#include <linux/if_vlan.h>
+#include <net/net_namespace.h>
+#include <net/netns/generic.h>
+#include "vlanproc.h"
+#include "vlan.h"
+
+/****** Function Prototypes *************************************************/
+
+/* Methods for preparing data for reading proc entries */
+static int vlan_seq_show(struct seq_file *seq, void *v);
+static void *vlan_seq_start(struct seq_file *seq, loff_t *pos);
+static void *vlan_seq_next(struct seq_file *seq, void *v, loff_t *pos);
+static void vlan_seq_stop(struct seq_file *seq, void *);
+static int vlandev_seq_show(struct seq_file *seq, void *v);
+
+/*
+ *	Global Data
+ */
+
+
+/*
+ *	Names of the proc directory entries
+ */
+
+static const char name_root[]	 = "vlan";
+static const char name_conf[]	 = "config";
+
+/*
+ *	Structures for interfacing with the /proc filesystem.
+ *	VLAN creates its own directory /proc/net/vlan with the following
+ *	entries:
+ *	config		device status/configuration
+ *	<device>	entry for each  device
+ */
+
+/*
+ *	Generic /proc/net/vlan/<file> file and inode operations
+ */
+
+static const struct seq_operations vlan_seq_ops = {
+	.start = vlan_seq_start,
+	.next = vlan_seq_next,
+	.stop = vlan_seq_stop,
+	.show = vlan_seq_show,
+};
+
+/*
+ * Proc filesystem directory entries.
+ */
+
+/* Strings */
+static const char *const vlan_name_type_str[VLAN_NAME_TYPE_HIGHEST] = {
+    [VLAN_NAME_TYPE_RAW_PLUS_VID]        = "VLAN_NAME_TYPE_RAW_PLUS_VID",
+    [VLAN_NAME_TYPE_PLUS_VID_NO_PAD]	 = "VLAN_NAME_TYPE_PLUS_VID_NO_PAD",
+    [VLAN_NAME_TYPE_RAW_PLUS_VID_NO_PAD] = "VLAN_NAME_TYPE_RAW_PLUS_VID_NO_PAD",
+    [VLAN_NAME_TYPE_PLUS_VID]		 = "VLAN_NAME_TYPE_PLUS_VID",
+};
+/*
+ *	Interface functions
+ */
+
+/*
+ *	Clean up /proc/net/vlan entries
+ */
+
+void vlan_proc_cleanup(struct net *net)
+{
+	struct vlan_net *vn = net_generic(net, vlan_net_id);
+
+	if (vn->proc_vlan_conf)
+		remove_proc_entry(name_conf, vn->proc_vlan_dir);
+
+	if (vn->proc_vlan_dir)
+		remove_proc_entry(name_root, net->proc_net);
+
+	/* Dynamically added entries should be cleaned up as their vlan_device
+	 * is removed, so we should not have to take care of it here...
+	 */
+}
+
+/*
+ *	Create /proc/net/vlan entries
+ */
+
+int __net_init vlan_proc_init(struct net *net)
+{
+	struct vlan_net *vn = net_generic(net, vlan_net_id);
+
+	vn->proc_vlan_dir = proc_net_mkdir(net, name_root, net->proc_net);
+	if (!vn->proc_vlan_dir)
+		goto err;
+
+	vn->proc_vlan_conf = proc_create_net(name_conf, S_IFREG | 0600,
+			vn->proc_vlan_dir, &vlan_seq_ops,
+			sizeof(struct seq_net_private));
+	if (!vn->proc_vlan_conf)
+		goto err;
+	return 0;
+
+err:
+	pr_err("can't create entry in proc filesystem!\n");
+	vlan_proc_cleanup(net);
+	return -ENOBUFS;
+}
+
+/*
+ *	Add directory entry for VLAN device.
+ */
+
+int vlan_proc_add_dev(struct net_device *vlandev)
+{
+	struct vlan_dev_priv *vlan = vlan_dev_priv(vlandev);
+	struct vlan_net *vn = net_generic(dev_net(vlandev), vlan_net_id);
+
+	if (!strcmp(vlandev->name, name_conf))
+		return -EINVAL;
+	vlan->dent = proc_create_single_data(vlandev->name, S_IFREG | 0600,
+			vn->proc_vlan_dir, vlandev_seq_show, vlandev);
+	if (!vlan->dent)
+		return -ENOBUFS;
+	return 0;
+}
+
+/*
+ *	Delete directory entry for VLAN device.
+ */
+void vlan_proc_rem_dev(struct net_device *vlandev)
+{
+	/** NOTE:  This will consume the memory pointed to by dent, it seems. */
+	proc_remove(vlan_dev_priv(vlandev)->dent);
+	vlan_dev_priv(vlandev)->dent = NULL;
+}
+
+/****** Proc filesystem entry points ****************************************/
+
+/*
+ * The following few functions build the content of /proc/net/vlan/config
+ */
+
+static void *vlan_seq_from_index(struct seq_file *seq, loff_t *pos)
+{
+	unsigned long ifindex = *pos;
+	struct net_device *dev;
+
+	for_each_netdev_dump(seq_file_net(seq), dev, ifindex) {
+		if (!is_vlan_dev(dev))
+			continue;
+		*pos = dev->ifindex;
+		return dev;
+	}
+	return NULL;
+}
+
+static void *vlan_seq_start(struct seq_file *seq, loff_t *pos)
+	__acquires(rcu)
+{
+	rcu_read_lock();
+	if (*pos == 0)
+		return SEQ_START_TOKEN;
+
+	return vlan_seq_from_index(seq, pos);
+}
+
+static void *vlan_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	++*pos;
+	return vlan_seq_from_index(seq, pos);
+}
+
+static void vlan_seq_stop(struct seq_file *seq, void *v)
+	__releases(rcu)
+{
+	rcu_read_unlock();
+}
+
+static int vlan_seq_show(struct seq_file *seq, void *v)
+{
+	struct net *net = seq_file_net(seq);
+	struct vlan_net *vn = net_generic(net, vlan_net_id);
+
+	if (v == SEQ_START_TOKEN) {
+		const char *nmtype = NULL;
+
+		seq_puts(seq, "VLAN Dev name	 | VLAN ID\n");
+
+		if (vn->name_type < ARRAY_SIZE(vlan_name_type_str))
+		    nmtype =  vlan_name_type_str[vn->name_type];
+
+		seq_printf(seq, "Name-Type: %s\n",
+			   nmtype ? nmtype :  "UNKNOWN");
+	} else {
+		const struct net_device *vlandev = v;
+		const struct vlan_dev_priv *vlan = vlan_dev_priv(vlandev);
+
+		seq_printf(seq, "%-15s| %d  | %s\n",  vlandev->name,
+			   vlan->vlan_id,    vlan->real_dev->name);
+	}
+	return 0;
+}
+
+static int vlandev_seq_show(struct seq_file *seq, void *offset)
+{
+	struct net_device *vlandev = (struct net_device *) seq->private;
+	const struct vlan_dev_priv *vlan = vlan_dev_priv(vlandev);
+	struct rtnl_link_stats64 temp;
+	const struct rtnl_link_stats64 *stats;
+	static const char fmt64[] = "%30s %12llu\n";
+	int i;
+
+	if (!is_vlan_dev(vlandev))
+		return 0;
+
+	stats = dev_get_stats(vlandev, &temp);
+	seq_printf(seq,
+		   "%s  VID: %d	 REORDER_HDR: %i  dev->priv_flags: %x\n",
+		   vlandev->name, vlan->vlan_id,
+		   (int)(vlan->flags & 1), (u32)vlandev->priv_flags);
+
+	seq_printf(seq, fmt64, "total frames received", stats->rx_packets);
+	seq_printf(seq, fmt64, "total bytes received", stats->rx_bytes);
+	seq_printf(seq, fmt64, "Broadcast/Multicast Rcvd", stats->multicast);
+	seq_puts(seq, "\n");
+	seq_printf(seq, fmt64, "total frames transmitted", stats->tx_packets);
+	seq_printf(seq, fmt64, "total bytes transmitted", stats->tx_bytes);
+	seq_printf(seq, "Device: %s", vlan->real_dev->name);
+	/* now show all PRIORITY mappings relating to this VLAN */
+	seq_printf(seq, "\nINGRESS priority mappings: "
+			"0:%u  1:%u  2:%u  3:%u  4:%u  5:%u  6:%u 7:%u\n",
+		   vlan->ingress_priority_map[0],
+		   vlan->ingress_priority_map[1],
+		   vlan->ingress_priority_map[2],
+		   vlan->ingress_priority_map[3],
+		   vlan->ingress_priority_map[4],
+		   vlan->ingress_priority_map[5],
+		   vlan->ingress_priority_map[6],
+		   vlan->ingress_priority_map[7]);
+
+	seq_printf(seq, " EGRESS priority mappings: ");
+	rcu_read_lock();
+	for (i = 0; i < 16; i++) {
+		const struct vlan_priority_tci_mapping *mp =
+			rcu_dereference(vlan->egress_priority_map[i]);
+		while (mp) {
+			u16 vlan_qos = READ_ONCE(mp->vlan_qos);
+
+			seq_printf(seq, "%u:%d ",
+				   mp->priority, ((vlan_qos >> 13) & 0x7));
+			mp = rcu_dereference(mp->next);
+		}
+	}
+	rcu_read_unlock();
+	seq_puts(seq, "\n");
+
+	return 0;
+}