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, 85 insertions, 0 deletions

diff --git a/fs/lockd/xdr.h b/fs/lockd/xdr.h
new file mode 100644
index 000000000..a1126cca9
--- /dev/null
+++ b/fs/lockd/xdr.h
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * XDR types for the NLM protocol
+ *
+ * Copyright (C) 1996 Olaf Kirch <okir@monad.swb.de>
+ */
+
+#ifndef _LOCKD_XDR_H
+#define _LOCKD_XDR_H
+
+#include <linux/fs.h>
+#include <linux/filelock.h>
+#include <linux/nfs.h>
+#include <linux/sunrpc/xdr.h>
+
+#define SM_MAXSTRLEN		1024
+#define SM_PRIV_SIZE		16
+
+struct nsm_private {
+	unsigned char		data[SM_PRIV_SIZE];
+};
+
+#define NLM_MAXCOOKIELEN    	32
+#define NLM_MAXSTRLEN		1024
+
+#define	nlm_granted		cpu_to_be32(NLM_LCK_GRANTED)
+#define	nlm_lck_denied		cpu_to_be32(NLM_LCK_DENIED)
+#define	nlm_lck_denied_nolocks	cpu_to_be32(NLM_LCK_DENIED_NOLOCKS)
+#define	nlm_lck_blocked		cpu_to_be32(NLM_LCK_BLOCKED)
+#define	nlm_lck_denied_grace_period	cpu_to_be32(NLM_LCK_DENIED_GRACE_PERIOD)
+
+/* Lock info passed via NLM */
+struct lockd_lock {
+	char *			caller;
+	unsigned int		len; 	/* length of "caller" */
+	struct nfs_fh		fh;
+	struct xdr_netobj	oh;
+	u32			svid;
+	u64			lock_start;
+	u64			lock_len;
+	struct file_lock	fl;
+};
+
+/*
+ *	NLM cookies. Technically they can be 1K, but Linux only uses 8 bytes.
+ *	FreeBSD uses 16, Apple Mac OS X 10.3 uses 20. Therefore we set it to
+ *	32 bytes.
+ */
+
+struct lockd_cookie {
+	unsigned char data[NLM_MAXCOOKIELEN];
+	unsigned int len;
+};
+
+/*
+ * Generic lockd arguments for all but sm_notify
+ */
+struct lockd_args {
+	struct lockd_cookie	cookie;
+	struct lockd_lock	lock;
+	u32			block;
+	u32			reclaim;
+	u32			state;
+};
+
+/*
+ * Generic lockd result
+ */
+struct lockd_res {
+	struct lockd_cookie	cookie;
+	__be32			status;
+	struct lockd_lock	lock;
+};
+
+/*
+ * statd callback when client has rebooted
+ */
+struct lockd_reboot {
+	char			*mon;
+	unsigned int		len;
+	u32			state;
+	struct nsm_private	priv;
+};
+
+#endif /* _LOCKD_XDR_H */