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, 116 insertions, 0 deletions

diff --git a/tools/tracing/rtla/Makefile.config b/tools/tracing/rtla/Makefile.config
new file mode 100644
index 000000000..0bdd258b7
--- /dev/null
+++ b/tools/tracing/rtla/Makefile.config
@@ -0,0 +1,116 @@
+# SPDX-License-Identifier: GPL-2.0-only
+
+include $(srctree)/tools/scripts/utilities.mak
+
+STOP_ERROR :=
+
+LIBTRACEEVENT_MIN_VERSION = 1.5
+LIBTRACEFS_MIN_VERSION = 1.6
+
+ifndef ($(NO_LIBTRACEEVENT),1)
+  ifeq ($(call get-executable,$(PKG_CONFIG)),)
+    $(error Error: $(PKG_CONFIG) needed by libtraceevent/libtracefs is missing on this system, please install it)
+  endif
+endif
+
+define lib_setup
+  $(eval LIB_INCLUDES += $(shell sh -c "$(PKG_CONFIG) --cflags lib$(1)"))
+  $(eval LDFLAGS += $(shell sh -c "$(PKG_CONFIG) --libs-only-L lib$(1)"))
+  $(eval EXTLIBS += $(shell sh -c "$(PKG_CONFIG) --libs-only-l lib$(1)"))
+endef
+
+$(call feature_check,libtraceevent)
+ifeq ($(feature-libtraceevent), 1)
+  $(call detected,CONFIG_LIBTRACEEVENT)
+
+  TEST = $(shell sh -c "$(PKG_CONFIG) --atleast-version $(LIBTRACEEVENT_MIN_VERSION) libtraceevent > /dev/null 2>&1 && echo y || echo n")
+  ifeq ($(TEST),n)
+    $(info libtraceevent version is too low, it must be at least $(LIBTRACEEVENT_MIN_VERSION))
+    STOP_ERROR := 1
+  endif
+
+  $(call lib_setup,traceevent)
+else
+  STOP_ERROR := 1
+  $(info libtraceevent is missing. Please install libtraceevent-dev/libtraceevent-devel)
+endif
+
+$(call feature_check,libtracefs)
+ifeq ($(feature-libtracefs), 1)
+  $(call detected,CONFIG_LIBTRACEFS)
+
+  TEST = $(shell sh -c "$(PKG_CONFIG) --atleast-version $(LIBTRACEFS_MIN_VERSION) libtracefs > /dev/null 2>&1 && echo y || echo n")
+  ifeq ($(TEST),n)
+    $(info libtracefs version is too low, it must be at least $(LIBTRACEFS_MIN_VERSION))
+    STOP_ERROR := 1
+  endif
+
+  $(call lib_setup,tracefs)
+else
+  STOP_ERROR := 1
+  $(info libtracefs is missing. Please install libtracefs-dev/libtracefs-devel)
+endif
+
+$(call feature_check,libcpupower)
+ifeq ($(feature-libcpupower), 1)
+  $(call detected,CONFIG_LIBCPUPOWER)
+  CFLAGS += -DHAVE_LIBCPUPOWER_SUPPORT
+  EXTLIBS += -lcpupower
+else
+  $(info libcpupower is missing, building without --deepest-idle-state support.)
+  $(info Please install libcpupower-dev/kernel-tools-libs-devel)
+endif
+
+$(call feature_check,libcheck)
+ifeq ($(feature-libcheck), 1)
+  $(call detected,CONFIG_LIBCHECK)
+else
+  $(info libcheck is missing, building without unit tests support.)
+  $(info Please install check-devel/check)
+endif
+
+ifndef BUILD_BPF_SKEL
+  # BPF skeletons are used to implement improved sample collection, enable
+  # them by default.
+  BUILD_BPF_SKEL := 1
+endif
+
+ifeq ($(BUILD_BPF_SKEL),0)
+  $(info BPF skeleton support disabled, building without BPF skeleton support.)
+endif
+
+$(call feature_check,libbpf)
+ifeq ($(feature-libbpf), 1)
+  $(call detected,CONFIG_LIBBPF)
+else
+  $(info libbpf is missing, building without BPF skeleton support.)
+  $(info Please install libbpf-dev/libbpf-devel)
+  BUILD_BPF_SKEL := 0
+endif
+
+$(call feature_check,clang-bpf-co-re)
+ifeq ($(feature-clang-bpf-co-re), 1)
+  $(call detected,CONFIG_CLANG_BPF_CO_RE)
+else
+  $(info clang is missing or does not support BPF CO-RE, building without BPF skeleton support.)
+  $(info Please install clang)
+  BUILD_BPF_SKEL := 0
+endif
+
+$(call feature_check,bpftool-skeletons)
+ifeq ($(feature-bpftool-skeletons), 1)
+  $(call detected,CONFIG_BPFTOOL_SKELETONS)
+else
+  $(info bpftool is missing or not supporting skeletons, building without BPF skeleton support.)
+  $(info Please install bpftool)
+  BUILD_BPF_SKEL := 0
+endif
+
+ifeq ($(BUILD_BPF_SKEL),1)
+  CFLAGS += -DHAVE_BPF_SKEL
+  EXTLIBS += -lbpf
+endif
+
+ifeq ($(STOP_ERROR),1)
+  $(error Please, check the errors above.)
+endif