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, 53 insertions, 0 deletions

diff --git a/Documentation/admin-guide/cifs/introduction.rst b/Documentation/admin-guide/cifs/introduction.rst
new file mode 100644
index 000000000..ffc6e2564
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+++ b/Documentation/admin-guide/cifs/introduction.rst
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+============
+Introduction
+============
+
+  This is the client VFS module for the SMB3 NAS protocol as well
+  as for older dialects such as the Common Internet File System (CIFS)
+  protocol which was the successor to the Server Message Block
+  (SMB) protocol, the native file sharing mechanism for most early
+  PC operating systems. New and improved versions of CIFS are now
+  called SMB2 and SMB3. Use of SMB3 (and later, including SMB3.1.1
+  the most current dialect) is strongly preferred over using older
+  dialects like CIFS due to security reasons. All modern dialects,
+  including the most recent, SMB3.1.1, are supported by the CIFS VFS
+  module. The SMB3 protocol is implemented and supported by all major
+  file servers such as Windows (including Windows 2019 Server), as
+  well as by Samba (which provides excellent CIFS/SMB2/SMB3 server
+  support and tools for Linux and many other operating systems).
+  Apple systems also support SMB3 well, as do most Network Attached
+  Storage vendors, so this network filesystem client can mount to a
+  wide variety of systems. It also supports mounting to the cloud
+  (for example Microsoft Azure), including the necessary security
+  features.
+
+  The intent of this module is to provide the most advanced network
+  file system function for SMB3 compliant servers, including advanced
+  security features, excellent parallelized high performance i/o, better
+  POSIX compliance, secure per-user session establishment, encryption,
+  high performance safe distributed caching (leases/oplocks), optional packet
+  signing, large files, Unicode support and other internationalization
+  improvements. Since both Samba server and this filesystem client support the
+  CIFS Unix extensions, and the Linux client also supports SMB3 POSIX extensions,
+  the combination can provide a reasonable alternative to other network and
+  cluster file systems for fileserving in some Linux to Linux environments,
+  not just in Linux to Windows (or Linux to Mac) environments.
+
+  This filesystem has a mount utility (mount.cifs) and various user space
+  tools (including smbinfo and setcifsacl) that can be obtained from
+
+      https://git.samba.org/?p=cifs-utils.git
+
+  or
+
+      git://git.samba.org/cifs-utils.git
+
+  mount.cifs should be installed in the directory with the other mount helpers.
+
+  For more information on the module see the project wiki page at
+
+      https://wiki.samba.org/index.php/LinuxCIFS
+
+  and
+
+      https://wiki.samba.org/index.php/LinuxCIFS_utils