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, 155 insertions, 0 deletions

diff --git a/Documentation/driver-api/80211/mac80211.rst b/Documentation/driver-api/80211/mac80211.rst
new file mode 100644
index 000000000..e38a22040
--- /dev/null
+++ b/Documentation/driver-api/80211/mac80211.rst
@@ -0,0 +1,155 @@
+===========================
+mac80211 subsystem (basics)
+===========================
+
+You should read and understand the information contained within this
+part of the book while implementing a mac80211 driver. In some chapters,
+advanced usage is noted, those may be skipped if this isn't needed.
+
+This part of the book only covers station and monitor mode
+functionality, additional information required to implement the other
+modes is covered in the second part of the book.
+
+Basic hardware handling
+=======================
+
+TBD
+
+This chapter shall contain information on getting a hw struct allocated
+and registered with mac80211.
+
+Since it is required to allocate rates/modes before registering a hw
+struct, this chapter shall also contain information on setting up the
+rate/mode structs.
+
+Additionally, some discussion about the callbacks and the general
+programming model should be in here, including the definition of
+ieee80211_ops which will be referred to a lot.
+
+Finally, a discussion of hardware capabilities should be done with
+references to other parts of the book.
+
+.. kernel-doc:: include/net/mac80211.h
+   :functions:
+	ieee80211_hw
+	ieee80211_hw_flags
+	SET_IEEE80211_DEV
+	SET_IEEE80211_PERM_ADDR
+	ieee80211_ops
+	ieee80211_alloc_hw
+	ieee80211_register_hw
+	ieee80211_unregister_hw
+	ieee80211_free_hw
+
+PHY configuration
+=================
+
+TBD
+
+This chapter should describe PHY handling including start/stop callbacks
+and the various structures used.
+
+.. kernel-doc:: include/net/mac80211.h
+   :functions:
+	ieee80211_conf
+	ieee80211_conf_flags
+
+Virtual interfaces
+==================
+
+TBD
+
+This chapter should describe virtual interface basics that are relevant
+to the driver (VLANs, MGMT etc are not.) It should explain the use of
+the add_iface/remove_iface callbacks as well as the interface
+configuration callbacks.
+
+Things related to AP mode should be discussed there.
+
+Things related to supporting multiple interfaces should be in the
+appropriate chapter, a BIG FAT note should be here about this though and
+the recommendation to allow only a single interface in STA mode at
+first!
+
+.. kernel-doc:: include/net/mac80211.h
+   :functions: ieee80211_vif
+
+Receive and transmit processing
+===============================
+
+what should be here
+-------------------
+
+TBD
+
+This should describe the receive and transmit paths in mac80211/the
+drivers as well as transmit status handling.
+
+Frame format
+------------
+
+.. kernel-doc:: include/net/mac80211.h
+   :doc: Frame format
+
+Packet alignment
+----------------
+
+.. kernel-doc:: net/mac80211/rx.c
+   :doc: Packet alignment
+
+Calling into mac80211 from interrupts
+-------------------------------------
+
+.. kernel-doc:: include/net/mac80211.h
+   :doc: Calling mac80211 from interrupts
+
+functions/definitions
+---------------------
+
+.. kernel-doc:: include/net/mac80211.h
+   :functions:
+	ieee80211_rx_status
+	mac80211_rx_encoding_flags
+	mac80211_rx_flags
+	mac80211_tx_info_flags
+	mac80211_tx_control_flags
+	mac80211_rate_control_flags
+	ieee80211_tx_rate
+	ieee80211_tx_info
+	ieee80211_tx_info_clear_status
+	ieee80211_rx
+	ieee80211_rx_ni
+	ieee80211_rx_irqsafe
+	ieee80211_tx_status_skb
+	ieee80211_tx_status_ni
+	ieee80211_tx_status_irqsafe
+	ieee80211_rts_get
+	ieee80211_rts_duration
+	ieee80211_ctstoself_get
+	ieee80211_ctstoself_duration
+	ieee80211_generic_frame_duration
+	ieee80211_wake_queue
+	ieee80211_stop_queue
+	ieee80211_wake_queues
+	ieee80211_stop_queues
+	ieee80211_queue_stopped
+
+Frame filtering
+===============
+
+.. kernel-doc:: include/net/mac80211.h
+   :doc: Frame filtering
+
+.. kernel-doc:: include/net/mac80211.h
+   :functions: ieee80211_filter_flags
+
+The mac80211 workqueue
+======================
+
+.. kernel-doc:: include/net/mac80211.h
+   :doc: mac80211 workqueue
+
+.. kernel-doc:: include/net/mac80211.h
+   :functions:
+	ieee80211_queue_work
+	ieee80211_queue_delayed_work