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, 107 insertions, 0 deletions

diff --git a/fs/lockd/trace.h b/fs/lockd/trace.h
new file mode 100644
index 000000000..a11d04e8c
--- /dev/null
+++ b/fs/lockd/trace.h
@@ -0,0 +1,107 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM lockd
+
+#if !defined(_TRACE_LOCKD_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_LOCKD_H
+
+#include <linux/tracepoint.h>
+#include <linux/crc32.h>
+#include <linux/nfs.h>
+
+#include "lockd.h"
+
+#ifdef CONFIG_LOCKD_V4
+#define NLM_STATUS_LIST					\
+	nlm_status_code(LCK_GRANTED)			\
+	nlm_status_code(LCK_DENIED)			\
+	nlm_status_code(LCK_DENIED_NOLOCKS)		\
+	nlm_status_code(LCK_BLOCKED)			\
+	nlm_status_code(LCK_DENIED_GRACE_PERIOD)	\
+	nlm_status_code(DEADLCK)			\
+	nlm_status_code(ROFS)				\
+	nlm_status_code(STALE_FH)			\
+	nlm_status_code(FBIG)				\
+	nlm_status_code_end(FAILED)
+#else
+#define NLM_STATUS_LIST					\
+	nlm_status_code(LCK_GRANTED)			\
+	nlm_status_code(LCK_DENIED)			\
+	nlm_status_code(LCK_DENIED_NOLOCKS)		\
+	nlm_status_code(LCK_BLOCKED)			\
+	nlm_status_code_end(LCK_DENIED_GRACE_PERIOD)
+#endif
+
+#undef nlm_status_code
+#undef nlm_status_code_end
+#define nlm_status_code(x)	TRACE_DEFINE_ENUM(NLM_##x);
+#define nlm_status_code_end(x)	TRACE_DEFINE_ENUM(NLM_##x);
+
+NLM_STATUS_LIST
+
+#undef nlm_status_code
+#undef nlm_status_code_end
+#define nlm_status_code(x)	{ NLM_##x, #x },
+#define nlm_status_code_end(x)	{ NLM_##x, #x }
+
+#define show_nlm_status(x)	__print_symbolic(x, NLM_STATUS_LIST)
+
+DECLARE_EVENT_CLASS(nlmclnt_lock_event,
+		TP_PROTO(
+			const struct lockd_lock *lock,
+			const struct sockaddr *addr,
+			unsigned int addrlen,
+			__be32 status
+		),
+
+		TP_ARGS(lock, addr, addrlen, status),
+
+		TP_STRUCT__entry(
+			__field(u32, oh)
+			__field(u32, svid)
+			__field(u32, fh)
+			__field(unsigned long, status)
+			__field(loff_t, start)
+			__field(loff_t, end)
+			__sockaddr(addr, addrlen)
+		),
+
+		TP_fast_assign(
+			__entry->oh = ~crc32_le(0xffffffff, lock->oh.data, lock->oh.len);
+			__entry->svid = lock->svid;
+			__entry->fh = nfs_fhandle_hash(&lock->fh);
+			__entry->start = lock->fl.fl_start;
+			__entry->end = lock->fl.fl_end;
+			__entry->status = be32_to_cpu(status);
+			__assign_sockaddr(addr, addr, addrlen);
+		),
+
+		TP_printk(
+			"addr=%pISpc oh=0x%08x svid=0x%08x fh=0x%08x start=%lld end=%lld status=%s",
+			__get_sockaddr(addr), __entry->oh, __entry->svid,
+			__entry->fh, __entry->start, __entry->end,
+			show_nlm_status(__entry->status)
+		)
+);
+
+#define DEFINE_NLMCLNT_EVENT(name)				\
+	DEFINE_EVENT(nlmclnt_lock_event, name,			\
+			TP_PROTO(				\
+				const struct lockd_lock *lock,	\
+				const struct sockaddr *addr,	\
+				unsigned int addrlen,		\
+				__be32	status			\
+			),					\
+			TP_ARGS(lock, addr, addrlen, status))
+
+DEFINE_NLMCLNT_EVENT(nlmclnt_test);
+DEFINE_NLMCLNT_EVENT(nlmclnt_lock);
+DEFINE_NLMCLNT_EVENT(nlmclnt_unlock);
+DEFINE_NLMCLNT_EVENT(nlmclnt_grant);
+
+#endif /* _TRACE_LOCKD_H */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#define TRACE_INCLUDE_FILE trace
+#include <trace/define_trace.h>