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, 41 insertions, 0 deletions

diff --git a/scripts/atomic/atomics.tbl b/scripts/atomic/atomics.tbl
new file mode 100644
index 000000000..903946cbf
--- /dev/null
+++ b/scripts/atomic/atomics.tbl
@@ -0,0 +1,41 @@
+# name	meta	args...
+#
+# Where meta contains a string of variants to generate.
+# Upper-case implies _{acquire,release,relaxed} variants.
+# Valid meta values are:
+# * B/b	- bool: returns bool
+# * v	- void: returns void
+# * I/i	- int: returns base type
+# * R	- return: returns base type (has _return variants)
+# * F/f	- fetch: returns base type (has fetch_ variants)
+# * l	- load: returns base type (has _acquire order variant)
+# * s	- store: returns void (has _release order variant)
+#
+# Where args contains list of type[:name], where type is:
+# * cv	- const pointer to atomic base type (atomic_t/atomic64_t/atomic_long_t)
+# * v	- pointer to atomic base type (atomic_t/atomic64_t/atomic_long_t)
+# * i	- base type (int/s64/long)
+# * p	- pointer to base type (int/s64/long)
+#
+read			l	cv
+set			s	v	i
+add			vRF	i	v
+sub			vRF	i	v
+inc			vRF	v
+dec			vRF	v
+and			vF	i	v
+andnot			vF	i	v
+or			vF	i	v
+xor			vF	i	v
+xchg			I	v	i:new
+cmpxchg			I	v	i:old	i:new
+try_cmpxchg		B	v	p:old	i:new
+sub_and_test		b	i	v
+dec_and_test		b	v
+inc_and_test		b	v
+add_negative		B	i	v
+add_unless		fb	v	i:a	i:u
+inc_not_zero		b	v
+inc_unless_negative	b	v
+dec_unless_positive	b	v
+dec_if_positive		i	v