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, 22 insertions, 0 deletions

diff --git a/fs/coda/Kconfig b/fs/coda/Kconfig
new file mode 100644
index 000000000..c3477eeaf
--- /dev/null
+++ b/fs/coda/Kconfig
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config CODA_FS
+	tristate "Coda file system support (advanced network fs)"
+	depends on INET
+	help
+	  Coda is an advanced network file system, similar to NFS in that it
+	  enables you to mount file systems of a remote server and access them
+	  with regular Unix commands as if they were sitting on your hard
+	  disk.  Coda has several advantages over NFS: support for
+	  disconnected operation (e.g. for laptops), read/write server
+	  replication, security model for authentication and encryption,
+	  persistent client caches and write back caching.
+
+	  If you say Y here, your Linux box will be able to act as a Coda
+	  *client*.  You will need user level code as well, both for the
+	  client and server.  Servers are currently user level, i.e. they need
+	  no kernel support.  Please read
+	  <file:Documentation/filesystems/coda.rst> and check out the Coda
+	  home page <http://www.coda.cs.cmu.edu/>.
+
+	  To compile the coda client support as a module, choose M here: the
+	  module will be called coda.