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, 75 insertions, 0 deletions

diff --git a/drivers/eisa/Kconfig b/drivers/eisa/Kconfig
new file mode 100644
index 000000000..a66b3be50
--- /dev/null
+++ b/drivers/eisa/Kconfig
@@ -0,0 +1,75 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# EISA configuration
+#
+
+config HAVE_EISA
+	bool
+
+menuconfig EISA
+	bool "EISA support"
+	depends on HAVE_EISA
+	help
+	  The Extended Industry Standard Architecture (EISA) bus was
+	  developed as an open alternative to the IBM MicroChannel bus.
+
+	  The EISA bus provided some of the features of the IBM MicroChannel
+	  bus while maintaining backward compatibility with cards made for
+	  the older ISA bus.  The EISA bus saw limited use between 1988 and
+	  1995 when it was made obsolete by the PCI bus.
+
+	  Say Y here if you are building a kernel for an EISA-based machine.
+
+	  Otherwise, say N.
+
+config EISA_VLB_PRIMING
+	bool "Vesa Local Bus priming"
+	depends on X86 && EISA
+	default n
+	help
+	  Activate this option if your system contains a Vesa Local
+	  Bus (VLB) card that identify itself as an EISA card (such as
+	  the Adaptec AHA-284x).
+
+	  When in doubt, say N.
+
+config EISA_PCI_EISA
+	bool "Generic PCI/EISA bridge"
+	depends on !PARISC && PCI && EISA
+	default y
+	help
+	  Activate this option if your system contains a PCI to EISA
+	  bridge. If your system have both PCI and EISA slots, you
+	  certainly need this option.
+
+	  When in doubt, say Y.
+
+# Using EISA_VIRTUAL_ROOT on something other than an X86 may lead
+# to crashes...
+
+config EISA_VIRTUAL_ROOT
+	bool "EISA virtual root device"
+	depends on EISA && X86
+	default y
+	help
+	  Activate this option if your system only have EISA bus
+	  (no PCI slots).
+
+	  When in doubt, say Y.
+
+config EISA_NAMES
+	bool "EISA device name database"
+	depends on EISA
+	default y
+	help
+	  By default, the kernel contains a database of all known EISA
+	  device names to make the information in sysfs comprehensible
+	  to the user. This database increases size of the kernel
+	  image by about 40KB, but it gets freed after the system
+	  boots up, so it doesn't take up kernel memory. Anyway, if
+	  you are building an installation floppy or kernel for an
+	  embedded system where kernel image size really matters, you
+	  can disable this feature and you'll get device ID instead of
+	  names.
+
+	  When in doubt, say Y.