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, 54 insertions, 0 deletions

diff --git a/drivers/iio/test/Kconfig b/drivers/iio/test/Kconfig
new file mode 100644
index 000000000..4fc17dd0d
--- /dev/null
+++ b/drivers/iio/test/Kconfig
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Industrial I/O subsystem unit tests configuration
+#
+
+# Keep in alphabetical order
+config IIO_GTS_KUNIT_TEST
+	tristate "Test IIO gain-time-scale helpers" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	select IIO_GTS_HELPER
+	default KUNIT_ALL_TESTS
+	help
+	  build unit tests for the IIO light sensor gain-time-scale helpers.
+
+	  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. Keep in alphabetical order
+
+config IIO_RESCALE_KUNIT_TEST
+	tristate "Test IIO rescale conversion functions" if !KUNIT_ALL_TESTS
+	depends on KUNIT && IIO_RESCALE
+	default KUNIT_ALL_TESTS
+	help
+	  Build unit tests for the iio-rescale code.
+
+	  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.
+
+config IIO_FORMAT_KUNIT_TEST
+	tristate "Test IIO formatting functions" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  build unit tests for the IIO formatting functions.
+
+	  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.
+
+config IIO_MULTIPLY_KUNIT_TEST
+	tristate "Test IIO multiply functions" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  build unit tests for the IIO multiply functions.
+
+	  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.