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, 35 insertions, 0 deletions

diff --git a/drivers/hwmon/occ/Kconfig b/drivers/hwmon/occ/Kconfig
new file mode 100644
index 000000000..348c21100
--- /dev/null
+++ b/drivers/hwmon/occ/Kconfig
@@ -0,0 +1,35 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# On-Chip Controller configuration
+#
+
+config SENSORS_OCC_P8_I2C
+	tristate "POWER8 OCC through I2C"
+	depends on I2C
+	select SENSORS_OCC
+	help
+	 This option enables support for monitoring sensors provided by the
+	 On-Chip Controller (OCC) on a POWER8 processor. However, this driver
+	 can only run on a baseboard management controller (BMC) connected to
+	 the P8, not the POWER processor itself. Communications with the OCC are
+	 established through I2C bus.
+
+	 This driver can also be built as a module. If so, the module will be
+	 called occ-p8-hwmon.
+
+config SENSORS_OCC_P9_SBE
+	tristate "POWER9 OCC through SBE"
+	depends on FSI_OCC
+	select SENSORS_OCC
+	help
+	 This option enables support for monitoring sensors provided by the
+	 On-Chip Controller (OCC) on a POWER9 processor. However, this driver
+	 can only run on a baseboard management controller (BMC) connected to
+	 the P9, not the POWER processor itself. Communications with the OCC are
+	 established through SBE fifo on an FSI bus.
+
+	 This driver can also be built as a module. If so, the module will be
+	 called occ-p9-hwmon.
+
+config SENSORS_OCC
+	tristate