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/drivers/hte/Kconfig b/drivers/hte/Kconfig
new file mode 100644
index 000000000..f57bad67d
--- /dev/null
+++ b/drivers/hte/Kconfig
@@ -0,0 +1,34 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menuconfig HTE
+	bool "Hardware Timestamping Engine (HTE) Support"
+	help
+	  Hardware Timestamping Engine (HTE) Support.
+
+	  Some devices provide a hardware timestamping engine which can
+	  timestamp certain device lines/signals in realtime. It comes with a
+	  benefit for the applications needing accurate timestamping event with
+	  less jitter. This framework provides a generic interface to such HTE
+	  providers and consumer devices.
+
+	  If unsure, say no.
+
+if HTE
+
+config HTE_TEGRA194
+	tristate "NVIDIA Tegra194 HTE Support"
+	depends on (ARCH_TEGRA || COMPILE_TEST)
+	depends on GPIOLIB
+	help
+	  Enable this option for integrated hardware timestamping engine also
+	  known as generic timestamping engine (GTE) support on NVIDIA Tegra194
+	  and later systems-on-chip. The driver supports 352 LIC IRQs and 39
+	  AON GPIOs lines for timestamping in realtime.
+
+config HTE_TEGRA194_TEST
+        tristate "NVIDIA Tegra194 HTE Test"
+        depends on (HTE_TEGRA194 || COMPILE_TEST)
+        help
+	  The NVIDIA Tegra194 GTE test driver demonstrates how to use HTE
+	  framework to timestamp GPIO and LIC IRQ lines.
+
+endif