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, 41 insertions, 0 deletions

diff --git a/arch/mips/kvm/Kconfig b/arch/mips/kvm/Kconfig
new file mode 100644
index 000000000..b1b9a1d67
--- /dev/null
+++ b/arch/mips/kvm/Kconfig
@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# KVM configuration
+#
+source "virt/kvm/Kconfig"
+
+menuconfig VIRTUALIZATION
+	bool "Virtualization"
+	help
+	  Say Y here to get to see options for using your Linux host to run
+	  other operating systems inside virtual machines (guests).
+	  This option alone does not add any kernel code.
+
+	  If you say N, all options in this submenu will be skipped and disabled.
+
+if VIRTUALIZATION
+
+config KVM
+	tristate "Kernel-based Virtual Machine (KVM) support"
+	depends on CPU_SUPPORTS_VZ
+	depends on MIPS_FP_SUPPORT
+	select EXPORT_UASM
+	select KVM_COMMON
+	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
+	select KVM_MMIO
+	select KVM_GENERIC_HARDWARE_ENABLING
+	select HAVE_KVM_READONLY_MEM
+	help
+	  Support for hosting Guest kernels.
+
+config KVM_MIPS_DEBUG_COP0_COUNTERS
+	bool "Maintain counters for COP0 accesses"
+	depends on KVM
+	help
+	  Maintain statistics for Guest COP0 accesses.
+	  A histogram of COP0 accesses is printed when the VM is
+	  shutdown.
+
+	  If unsure, say N.
+
+endif # VIRTUALIZATION