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, 44 insertions, 0 deletions

diff --git a/fs/afs/Kconfig b/fs/afs/Kconfig
new file mode 100644
index 000000000..682bd8ec2
--- /dev/null
+++ b/fs/afs/Kconfig
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config AFS_FS
+	tristate "Andrew File System support (AFS)"
+	depends on INET
+	select AF_RXRPC
+	select DNS_RESOLVER
+	select NETFS_SUPPORT
+	select CRYPTO_KRB5
+	help
+	  If you say Y here, you will get an experimental Andrew File System
+	  driver. It currently only supports unsecured read-only AFS access.
+
+	  See <file:Documentation/filesystems/afs.rst> for more information.
+
+	  If unsure, say N.
+
+config AFS_DEBUG
+	bool "AFS dynamic debugging"
+	depends on AFS_FS
+	help
+	  Say Y here to make runtime controllable debugging messages appear.
+
+	  See <file:Documentation/filesystems/afs.rst> for more information.
+
+	  If unsure, say N.
+
+config AFS_FSCACHE
+	bool "Provide AFS client caching support"
+	depends on AFS_FS=m && FSCACHE || AFS_FS=y && FSCACHE=y
+	help
+	  Say Y here if you want AFS data to be cached locally on disk through
+	  the generic filesystem cache manager
+
+config AFS_DEBUG_CURSOR
+	bool "AFS server cursor debugging"
+	depends on AFS_FS
+	help
+	  Say Y here to cause the contents of a server cursor to be dumped to
+	  the dmesg log if the server rotation algorithm fails to successfully
+	  contact a server.
+
+	  See <file:Documentation/filesystems/afs.rst> for more information.
+
+	  If unsure, say N.