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, 66 insertions, 0 deletions

diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile
new file mode 100644
index 000000000..e372fc021
--- /dev/null
+++ b/drivers/gpu/Makefile
@@ -0,0 +1,66 @@
+# SPDX-License-Identifier: GPL-2.0-only
+# drm/tegra depends on host1x, so if both drivers are built-in care must be
+# taken to initialize them in the correct order. Link order is the only way
+# to ensure this currently.
+# Similarly, buddy must come first since it is used by other drivers.
+obj-$(CONFIG_GPU_BUDDY)	+= buddy.o
+obj-y			+= host1x/ drm/ vga/ tests/
+obj-$(CONFIG_IMX_IPUV3_CORE)	+= ipu-v3/
+obj-$(CONFIG_TRACE_GPU_MEM)		+= trace/
+
+# nova-core and nova-drm are built from this Makefile so nova-drm's dependency
+# on nova-core can be expressed as a plain Make prerequisite rather than a
+# recursive sub-make. This is a temporary workaround until the Rust build
+# system supports cross-crate dependencies natively.
+
+obj-$(CONFIG_NOVA_CORE) += nova-core.o
+nova-core-y := nova-core/nova_core.o nova-core/nova_core_exports.o
+
+obj-$(CONFIG_DRM_NOVA) += nova-drm.o
+nova-drm-y := drm/nova/nova.o
+
+# Export Rust symbols from nova-core only if nova-drm actually references them.
+nova-core-export-deps := $(if $(CONFIG_DRM_NOVA),$(obj)/drm/nova/nova.o)
+
+rust_needed_exports = \
+	{ $(if $(strip $(2)),$(NM) -u $(2);,) echo "__DEFINED_RUST_SYMBOLS__"; \
+	  $(NM) -p --defined-only $(1); } | \
+	awk -v fmt='$(3)' ' \
+		/^__DEFINED_RUST_SYMBOLS__$$/ { defs = 1; next } \
+		!defs { if ($$NF ~ /^_R/) needed[$$NF] = 1; next } \
+		defs && $$2 ~ /(T|R|D|B)/ && $$3 ~ /^_R/ && \
+			$$3 !~ /_(init|cleanup)_module$$/ && \
+			$$3 !~ /__(pfx|cfi|odr_asan)/ && \
+			$$3 in needed { printf fmt, $$3 } \
+	'
+
+quiet_cmd_exports = EXPORTS $@
+      cmd_exports = \
+	$(call rust_needed_exports,$<,$(nova-core-export-deps),EXPORT_SYMBOL_RUST_GPL(%s);\n) > $@
+
+$(obj)/nova-core/exports_nova_core_generated.h: $(obj)/nova-core/nova_core.o $(nova-core-export-deps) FORCE
+	$(call if_changed,exports)
+
+targets += nova-core/exports_nova_core_generated.h
+
+$(obj)/nova-core/nova_core_exports.o: $(obj)/nova-core/exports_nova_core_generated.h
+CFLAGS_nova-core/nova_core_exports.o := -I $(objtree)/$(obj)/nova-core
+
+ifdef CONFIG_MODVERSIONS
+# The C export shim declares Rust symbols as `extern int`, so reuse its export
+# list but generate symbol CRCs from the Rust object instead of the shim's DWARF.
+$(obj)/nova-core/nova_core_exports.o: private cmd_gensymtypes_c = \
+	$(call getexportsymbols,\1) | \
+	$(objtree)/scripts/gendwarfksyms/gendwarfksyms \
+		$(if $(KBUILD_GENDWARFKSYMS_STABLE), --stable) \
+		$(if $(KBUILD_SYMTYPES), --symtypes $(@:.o=.symtypes),) \
+		$(obj)/nova-core/nova_core.o
+endif
+
+# Output nova-core's crate metadata for use by nova-drm at compile time.
+RUSTFLAGS_nova-core/nova_core.o += \
+	--emit=metadata=$(objtree)/$(obj)/nova-core/libnova_core.rmeta
+
+# Allow nova-drm to import nova-core's types.
+$(obj)/drm/nova/nova.o: $(obj)/nova-core/nova_core.o
+RUSTFLAGS_drm/nova/nova.o := -L $(objtree)/$(obj)/nova-core --extern nova_core