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, 29 insertions, 0 deletions

diff --git a/drivers/misc/bcm-vk/Kconfig b/drivers/misc/bcm-vk/Kconfig
new file mode 100644
index 000000000..68a972772
--- /dev/null
+++ b/drivers/misc/bcm-vk/Kconfig
@@ -0,0 +1,29 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Broadcom VK device
+#
+config BCM_VK
+	tristate "Support for Broadcom VK Accelerators"
+	depends on PCI_MSI
+	help
+	  Select this option to enable support for Broadcom
+	  VK Accelerators.  VK is used for performing
+	  multiple specific offload processing tasks in parallel.
+	  Such offload tasks assist in such operations as video
+	  transcoding, compression, and crypto tasks.
+	  This driver enables userspace programs to access these
+	  accelerators via /dev/bcm-vk.N devices.
+
+	  If unsure, say N.
+
+config BCM_VK_TTY
+	bool "Enable tty ports on a Broadcom VK Accelerator device"
+	depends on TTY
+	depends on BCM_VK
+	help
+	  Select this option to enable tty support to allow console
+	  access to Broadcom VK Accelerator cards from host.
+
+	  Device node will in the form /dev/bcm-vk.x_ttyVKy where:
+	  x is the instance of the VK card
+	  y is the tty device number on the VK card.