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, 25 insertions, 0 deletions

diff --git a/drivers/misc/cb710/Kconfig b/drivers/misc/cb710/Kconfig
new file mode 100644
index 000000000..a696d7509
--- /dev/null
+++ b/drivers/misc/cb710/Kconfig
@@ -0,0 +1,25 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config CB710_CORE
+	tristate "ENE CB710/720 Flash memory card reader support"
+	depends on PCI
+	help
+	  This option enables support for PCI ENE CB710/720 Flash memory card
+	  reader found in some laptops (ie. some versions of HP Compaq nx9500).
+
+	  You will also have to select some flash card format drivers (MMC/SD,
+	  MemoryStick).
+
+	  This driver can also be built as a module. If so, the module
+	  will be called cb710.
+
+config CB710_DEBUG
+	bool "Enable driver debugging"
+	depends on CB710_CORE != n
+	help
+	  This is an option for use by developers; most people should
+	  say N here.  This adds a lot of debugging output to dmesg.
+
+config CB710_DEBUG_ASSUMPTIONS
+	bool
+	depends on CB710_CORE != n
+	default y