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, 34 insertions, 0 deletions

diff --git a/net/nfc/Kconfig b/net/nfc/Kconfig
new file mode 100644
index 000000000..466a0279b
--- /dev/null
+++ b/net/nfc/Kconfig
@@ -0,0 +1,34 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# NFC subsystem configuration
+#
+
+menuconfig NFC
+	depends on RFKILL || !RFKILL
+	tristate "NFC subsystem support"
+	default n
+	help
+	  Say Y here if you want to build support for NFC (Near field
+	  communication) devices.
+
+	  To compile this support as a module, choose M here: the module will
+	  be called nfc.
+
+config NFC_DIGITAL
+	depends on NFC
+	select CRC_CCITT
+	select CRC_ITU_T
+	tristate "NFC Digital Protocol stack support"
+	default n
+	help
+	  Say Y if you want to build NFC digital protocol stack support.
+	  This is needed by NFC chipsets whose firmware only implement
+	  the NFC analog layer.
+
+	  To compile this support as a module, choose M here: the module will
+	  be called nfc_digital.
+
+source "net/nfc/nci/Kconfig"
+source "net/nfc/hci/Kconfig"
+
+source "drivers/nfc/Kconfig"