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/fs/adfs/Kconfig b/fs/adfs/Kconfig
new file mode 100644
index 000000000..1b97058f0
--- /dev/null
+++ b/fs/adfs/Kconfig
@@ -0,0 +1,29 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config ADFS_FS
+	tristate "ADFS file system support"
+	depends on BLOCK
+	select BUFFER_HEAD
+	help
+	  The Acorn Disc Filing System is the standard file system of the
+	  RiscOS operating system which runs on Acorn's ARM-based Risc PC
+	  systems and the Acorn Archimedes range of machines. If you say Y
+	  here, Linux will be able to read from ADFS partitions on hard drives
+	  and from ADFS-formatted floppy discs. If you also want to be able to
+	  write to those devices, say Y to "ADFS write support" below.
+
+	  The ADFS partition should be the first partition (i.e.,
+	  /dev/[hs]d?1) on each of your drives. Please read the file
+	  <file:Documentation/filesystems/adfs.rst> for further details.
+
+	  To compile this code as a module, choose M here: the module will be
+	  called adfs.
+
+	  If unsure, say N.
+
+config ADFS_FS_RW
+	bool "ADFS write support (DANGEROUS)"
+	depends on ADFS_FS
+	help
+	  If you say Y here, you will be able to write to ADFS partitions on
+	  hard drives and ADFS-formatted floppy disks. This is experimental
+	  codes, so if you're unsure, say N.