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, 39 insertions, 0 deletions

diff --git a/net/mptcp/Kconfig b/net/mptcp/Kconfig
new file mode 100644
index 000000000..be71fc9b4
--- /dev/null
+++ b/net/mptcp/Kconfig
@@ -0,0 +1,39 @@
+
+config MPTCP
+	bool "MPTCP: Multipath TCP"
+	depends on INET
+	select SKB_EXTENSIONS
+	select CRYPTO_LIB_SHA256
+	select CRYPTO_LIB_UTILS
+	help
+	  Multipath TCP (MPTCP) connections send and receive data over multiple
+	  subflows in order to utilize multiple network paths. Each subflow
+	  uses the TCP protocol, and TCP options carry header information for
+	  MPTCP.
+
+if MPTCP
+
+config INET_MPTCP_DIAG
+	depends on INET_DIAG
+	def_tristate INET_DIAG
+
+config MPTCP_IPV6
+	bool "MPTCP: IPv6 support for Multipath TCP"
+	depends on IPV6=y
+	default y
+
+config MPTCP_KUNIT_TEST
+	tristate "This builds the MPTCP KUnit tests" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  Currently covers the MPTCP crypto and token helpers.
+	  Only useful for kernel devs running KUnit test harness and are not
+	  for inclusion into a production build.
+
+	  For more information on KUnit and unit tests in general please refer
+	  to the KUnit documentation in Documentation/dev-tools/kunit/.
+
+	  If unsure, say N.
+
+endif