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, 124 insertions, 0 deletions

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
new file mode 100644
index 000000000..5b713837e
--- /dev/null
+++ b/tools/perf/Makefile
@@ -0,0 +1,124 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# This is a simple wrapper Makefile that calls the main Makefile.perf
+# with a -j option to do parallel builds
+#
+# If you want to invoke the perf build in some non-standard way then
+# you can use the 'make -f Makefile.perf' method to invoke it.
+#
+
+#
+# Clear out the built-in rules GNU make defines by default (such as .o targets),
+# so that we pass through all targets to Makefile.perf:
+#
+.SUFFIXES:
+
+#
+# We don't want to pass along options like -j:
+#
+unexport MAKEFLAGS
+
+#
+# Do a parallel build with multiple jobs, based on the number of CPUs online
+# in this system: 'make -j8' on a 8-CPU system, etc.
+#
+# (To override it, run 'make JOBS=1' and similar.)
+#
+ifeq ($(JOBS),)
+  JOBS := $(shell (getconf _NPROCESSORS_ONLN || grep -E -c '^processor|^CPU[0-9]' /proc/cpuinfo) 2>/dev/null)
+  ifeq ($(JOBS),0)
+    JOBS := 1
+  endif
+endif
+
+#
+# Only pass canonical directory names as the output directory:
+#
+ifneq ($(O),)
+  FULL_O := $(shell cd $(PWD); readlink -f $(O) || echo $(O))
+endif
+
+#
+# Only accept the 'DEBUG' variable from the command line:
+#
+ifeq ("$(origin DEBUG)", "command line")
+  ifeq ($(DEBUG),)
+    override DEBUG = 0
+  else
+    SET_DEBUG = "DEBUG=$(DEBUG)"
+  endif
+else
+  override DEBUG = 0
+endif
+
+ifeq ($(JOBS),1)
+  BUILD_TYPE := sequential
+else
+  BUILD_TYPE := parallel
+endif
+
+define print_msg
+  @printf '  BUILD:   Doing '\''make \033[33m-j'$(JOBS)'\033[m'\'' $(BUILD_TYPE) build\n'
+endef
+
+define make
+  @$(MAKE) -f Makefile.perf --no-print-directory -j$(JOBS) O=$(FULL_O) $(SET_DEBUG) $@
+endef
+
+#
+# Needed if no target specified:
+# (Except for tags and TAGS targets. The reason is that the
+# Makefile does not treat tags/TAGS as targets but as files
+# and thus won't rebuilt them once they are in place.)
+#
+all tags TAGS:
+	$(print_msg)
+	$(make)
+
+ifdef MAKECMDGOALS
+has_clean := 0
+ifneq ($(filter clean,$(MAKECMDGOALS)),)
+  has_clean := 1
+endif # clean
+
+ifeq ($(has_clean),1)
+  rest := $(filter-out clean,$(MAKECMDGOALS))
+  ifneq ($(rest),)
+$(rest): clean
+  endif # rest
+endif # has_clean
+endif # MAKECMDGOALS
+
+#
+# Explicitly disable parallelism for the clean target.
+#
+clean:
+	$(make) -j1
+
+#
+# The build-test target is not really parallel, don't print the jobs info,
+# it also uses only the tests/make targets that don't pollute the source
+# repository, i.e. that uses O= or builds the tarpkg outside the source
+# repo directories.
+#
+# For a full test, use:
+#
+# make -C tools/perf -f tests/make
+#
+build-test:
+	@$(MAKE) SHUF=1 -f tests/make REUSE_FEATURES_DUMP=1 MK=Makefile SET_PARALLEL=1 --no-print-directory tarpkg make_static make_with_gtk2 out
+
+build-test-tarball:
+	@$(MAKE) -f tests/make REUSE_FEATURES_DUMP=1 MK=Makefile SET_PARALLEL=1 --no-print-directory out
+
+check-headers:
+	@./check-headers.sh
+
+#
+# All other targets get passed through:
+#
+%: FORCE
+	$(print_msg)
+	$(make)
+
+.PHONY: tags TAGS FORCE Makefile build-test build-test-tarball check-headers