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, 105 insertions, 0 deletions

diff --git a/net/6lowpan/Kconfig b/net/6lowpan/Kconfig
new file mode 100644
index 000000000..d8fc45949
--- /dev/null
+++ b/net/6lowpan/Kconfig
@@ -0,0 +1,105 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menuconfig 6LOWPAN
+	tristate "6LoWPAN Support"
+	depends on IPV6
+	help
+	  This enables IPv6 over Low power Wireless Personal Area Network -
+	  "6LoWPAN" which is supported by IEEE 802.15.4 or Bluetooth stacks.
+
+config 6LOWPAN_DEBUGFS
+	bool "6LoWPAN debugfs support"
+	depends on 6LOWPAN
+	depends on DEBUG_FS
+	help
+	  This enables 6LoWPAN debugfs support. For example to manipulate
+	  IPHC context information at runtime.
+
+menuconfig 6LOWPAN_NHC
+	tristate "Next Header and Generic Header Compression Support"
+	depends on 6LOWPAN
+	default y
+	help
+	  Support for next header and generic header compression defined in
+	  RFC6282 and RFC7400.
+
+if 6LOWPAN_NHC
+
+config 6LOWPAN_NHC_DEST
+	tristate "Destination Options Header Support"
+	default y
+	help
+	  6LoWPAN IPv6 Destination Options Header compression according to
+	  RFC6282.
+
+config 6LOWPAN_NHC_FRAGMENT
+	tristate "Fragment Header Support"
+	default y
+	help
+	  6LoWPAN IPv6 Fragment Header compression according to RFC6282.
+
+config 6LOWPAN_NHC_HOP
+	tristate "Hop-by-Hop Options Header Support"
+	default y
+	help
+	  6LoWPAN IPv6 Hop-by-Hop Options Header compression according to
+	  RFC6282.
+
+config 6LOWPAN_NHC_IPV6
+	tristate "IPv6 Header Support"
+	default y
+	help
+	  6LoWPAN IPv6 Header compression according to RFC6282.
+
+config 6LOWPAN_NHC_MOBILITY
+	tristate "Mobility Header Support"
+	default y
+	help
+	  6LoWPAN IPv6 Mobility Header compression according to RFC6282.
+
+config 6LOWPAN_NHC_ROUTING
+	tristate "Routing Header Support"
+	default y
+	help
+	  6LoWPAN IPv6 Routing Header compression according to RFC6282.
+
+config 6LOWPAN_NHC_UDP
+	tristate "UDP Header Support"
+	default y
+	help
+	  6LoWPAN IPv6 UDP Header compression according to RFC6282.
+
+config 6LOWPAN_GHC_EXT_HDR_HOP
+	tristate "GHC Hop-by-Hop Options Header Support"
+	help
+	  6LoWPAN IPv6 Hop-by-Hop option generic header compression according
+	  to RFC7400.
+
+config 6LOWPAN_GHC_UDP
+	tristate "GHC UDP Support"
+	help
+	  6LoWPAN IPv6 UDP generic header compression according to RFC7400.
+
+config 6LOWPAN_GHC_ICMPV6
+	tristate "GHC ICMPv6 Support"
+	help
+	  6LoWPAN IPv6 ICMPv6 generic header compression according to RFC7400.
+
+config 6LOWPAN_GHC_EXT_HDR_DEST
+	tristate "GHC Destination Options Header Support"
+	help
+	  6LoWPAN IPv6 destination option generic header compression according
+	  to RFC7400.
+
+config 6LOWPAN_GHC_EXT_HDR_FRAG
+	tristate "GHC Fragmentation Options Header Support"
+	help
+	  6LoWPAN IPv6 fragmentation option generic header compression
+	  according to RFC7400.
+
+config 6LOWPAN_GHC_EXT_HDR_ROUTE
+	tristate "GHC Routing Options Header Support"
+	help
+	  6LoWPAN IPv6 routing option generic header compression according
+	  to RFC7400.
+
+endif