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, 141 insertions, 0 deletions

diff --git a/net/wireless/wext-proc.c b/net/wireless/wext-proc.c
new file mode 100644
index 000000000..be6b2b695
--- /dev/null
+++ b/net/wireless/wext-proc.c
@@ -0,0 +1,141 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file implement the Wireless Extensions proc API.
+ *
+ * Authors :	Jean Tourrilhes - HPL - <jt@hpl.hp.com>
+ * Copyright (c) 1997-2007 Jean Tourrilhes, All Rights Reserved.
+ */
+
+/*
+ * The /proc/net/wireless file is a human readable user-space interface
+ * exporting various wireless specific statistics from the wireless devices.
+ * This is the most popular part of the Wireless Extensions ;-)
+ *
+ * This interface is a pure clone of /proc/net/dev (in net/core/dev.c).
+ * The content of the file is basically the content of "struct iw_statistics".
+ */
+
+#include <linux/module.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/wireless.h>
+#include <linux/netdevice.h>
+#include <linux/rtnetlink.h>
+#include <net/iw_handler.h>
+#include <net/wext.h>
+
+
+static void wireless_seq_printf_stats(struct seq_file *seq,
+				      struct net_device *dev)
+{
+	/* Get stats from the driver */
+	struct iw_statistics *stats = get_wireless_stats(dev);
+	static struct iw_statistics nullstats = {};
+
+	/* show device if it's wireless regardless of current stats */
+	if (!stats) {
+#ifdef CONFIG_WIRELESS_EXT
+		if (dev->wireless_handlers)
+			stats = &nullstats;
+#endif
+#ifdef CONFIG_CFG80211
+		if (dev->ieee80211_ptr)
+			stats = &nullstats;
+#endif
+	}
+
+	if (stats) {
+		seq_printf(seq, "%6s: %04x  %3d%c  %3d%c  %3d%c  %6d %6d %6d "
+				"%6d %6d   %6d\n",
+			   dev->name, stats->status, stats->qual.qual,
+			   stats->qual.updated & IW_QUAL_QUAL_UPDATED
+			   ? '.' : ' ',
+			   ((__s32) stats->qual.level) -
+			   ((stats->qual.updated & IW_QUAL_DBM) ? 0x100 : 0),
+			   stats->qual.updated & IW_QUAL_LEVEL_UPDATED
+			   ? '.' : ' ',
+			   ((__s32) stats->qual.noise) -
+			   ((stats->qual.updated & IW_QUAL_DBM) ? 0x100 : 0),
+			   stats->qual.updated & IW_QUAL_NOISE_UPDATED
+			   ? '.' : ' ',
+			   stats->discard.nwid, stats->discard.code,
+			   stats->discard.fragment, stats->discard.retries,
+			   stats->discard.misc, stats->miss.beacon);
+
+		if (stats != &nullstats)
+			stats->qual.updated &= ~IW_QUAL_ALL_UPDATED;
+	}
+}
+
+/* ---------------------------------------------------------------- */
+/*
+ * Print info for /proc/net/wireless (print all entries)
+ */
+static int wireless_dev_seq_show(struct seq_file *seq, void *v)
+{
+	might_sleep();
+
+	if (v == SEQ_START_TOKEN)
+		seq_printf(seq, "Inter-| sta-|   Quality        |   Discarded "
+				"packets               | Missed | WE\n"
+				" face | tus | link level noise |  nwid  "
+				"crypt   frag  retry   misc | beacon | %d\n",
+			   WIRELESS_EXT);
+	else
+		wireless_seq_printf_stats(seq, v);
+	return 0;
+}
+
+static void *wireless_dev_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	struct net *net = seq_file_net(seq);
+	loff_t off;
+	struct net_device *dev;
+
+	rtnl_lock();
+	if (!*pos)
+		return SEQ_START_TOKEN;
+
+	off = 1;
+	for_each_netdev(net, dev)
+		if (off++ == *pos)
+			return dev;
+	return NULL;
+}
+
+static void *wireless_dev_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct net *net = seq_file_net(seq);
+
+	++*pos;
+
+	return v == SEQ_START_TOKEN ?
+		first_net_device(net) : next_net_device(v);
+}
+
+static void wireless_dev_seq_stop(struct seq_file *seq, void *v)
+{
+	rtnl_unlock();
+}
+
+static const struct seq_operations wireless_seq_ops = {
+	.start = wireless_dev_seq_start,
+	.next  = wireless_dev_seq_next,
+	.stop  = wireless_dev_seq_stop,
+	.show  = wireless_dev_seq_show,
+};
+
+int __net_init wext_proc_init(struct net *net)
+{
+	/* Create /proc/net/wireless entry */
+	if (!proc_create_net("wireless", 0444, net->proc_net,
+			&wireless_seq_ops, sizeof(struct seq_net_private)))
+		return -ENOMEM;
+
+	return 0;
+}
+
+void __net_exit wext_proc_exit(struct net *net)
+{
+	remove_proc_entry("wireless", net->proc_net);
+}