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, 49 insertions, 0 deletions

diff --git a/Documentation/crypto/libcrypto-unauth-encryption.rst b/Documentation/crypto/libcrypto-unauth-encryption.rst
new file mode 100644
index 000000000..b4639b892
--- /dev/null
+++ b/Documentation/crypto/libcrypto-unauth-encryption.rst
@@ -0,0 +1,49 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Unauthenticated encryption
+==========================
+
+These APIs provide support for unauthenticated encryption and decryption,
+including bare stream ciphers and other length-preserving algorithms such as
+block ciphers in XTS mode.  The legitimate use cases for these algorithms are:
+
+- Support for legacy protocols that really should have chosen an authenticated
+  mode (or even another primitive entirely) but didn't.
+
+- Internal components of authenticated modes.  For example, AES-CTR is used by
+  AES-GCM and AES-CCM internally.
+
+- Storage encryption that cannot accommodate ciphertext expansion.  Usually
+  AES-XTS is used for this.
+
+- Stream ciphers for key derivation and random number generation.
+
+Besides the above, these shouldn't be used.
+
+AES-CBC and AES-CBC-CTS
+-----------------------
+
+This API provides support for AES in the CBC and CBC-CTS modes of operation.
+
+.. kernel-doc:: include/crypto/aes-cbc.h
+
+AES-CTR and AES-XCTR
+--------------------
+
+This API provides support for AES in the CTR and XCTR modes of operation.
+
+.. kernel-doc:: include/crypto/aes-ctr.h
+
+AES-ECB
+-------
+
+This API provides support for AES in the ECB mode of operation.
+
+.. kernel-doc:: include/crypto/aes-ecb.h
+
+AES-XTS
+-------
+
+This API provides support for AES in the XTS mode of operation.
+
+.. kernel-doc:: include/crypto/aes-xts.h