Merge branches 'expcb.2026.07.24a', 'misc.2026.07.30a', 'rcu-tasks.2026.07.30a', 'srcu.2026.08.11a' and 'torture.2026.08.14a' into HEADgrafted

Changes:

Make expedited grace periods expedite normal RCU callbacks

Miscellaneous fixes:
 * Improve diagnostic output with character task states.
 * Mark accesses to inform KCSAN of concurrency design.
 * Move from kmalloc() to kmalloc_obj().
 * Documentation updates.
 * Improve handling of RCU deferred quiescent states.
 * Clean up unused function arguments and structure fields.
 * Reduce show_rcu_gp_kthreads() stack space.

Tasks RCU updates:
 * Clean up after SRCU re-implementation of Tasks Trace RCU.
 * Mark accesses to inform KCSAN of concurrency design.
 * Add ->lazy_timer status to diagnostic output.
 * Remove an unnecessary memory barrier.
 * Fix a data race, courtesy of KCSAN.
 * Documentation updates.
 * Convert cond_resched_tasks_rcu_qs() from macro to static inline
   function.

SRCU updates:
 * Add Rust helpers for SRCU.
 * Avoid losing queued work at cleanup_srcu_struct() time.

Torture-test updates:
 * Preparation work for immediate RCU priority deboosting.
 * Test RCU readers from real interrupt handlers (as opposed to softirq).
 * Simplify code through use of cpumask_next_wrap().
 * Improve diagnostic output with character task states.
 * Add rcutorture.nwriters parameter to allow lightweight stall testing,
   and rcutorture.stall_only to make doing so easier.
 * Test an RCU Tasks Trace grace period implying an RCU grace period.
 * Make RCU Tasks Trace torturing track reader batches.
 * Fix a data race, courtesy of KCSAN.
 * Plug a shuffle_tmp_mask memory leak on kthread spawn failure.

1 files changed, 202 insertions, 0 deletions

diff --git a/tools/lib/perf/Makefile b/tools/lib/perf/Makefile
new file mode 100644
index 000000000..32301a1d8
--- /dev/null
+++ b/tools/lib/perf/Makefile
@@ -0,0 +1,202 @@
+# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+# Most of this file is copied from tools/lib/bpf/Makefile
+
+LIBPERF_VERSION = 0
+LIBPERF_PATCHLEVEL = 0
+LIBPERF_EXTRAVERSION = 1
+
+MAKEFLAGS += --no-print-directory
+
+ifeq ($(srctree),)
+srctree := $(patsubst %/,%,$(dir $(CURDIR)))
+srctree := $(patsubst %/,%,$(dir $(srctree)))
+srctree := $(patsubst %/,%,$(dir $(srctree)))
+#$(info Determined 'srctree' to be $(srctree))
+endif
+
+INSTALL = install
+
+# Use DESTDIR for installing into a different root directory.
+# This is useful for building a package. The program will be
+# installed in this directory as if it was the root directory.
+# Then the build tool can move it later.
+DESTDIR ?=
+DESTDIR_SQ = '$(subst ','\'',$(DESTDIR))'
+
+include $(srctree)/tools/scripts/Makefile.include
+include $(srctree)/tools/scripts/Makefile.arch
+
+ifeq ($(LP64), 1)
+  libdir_relative = lib64
+else
+  libdir_relative = lib
+endif
+
+prefix ?=
+libdir = $(prefix)/$(libdir_relative)
+
+# Shell quotes
+libdir_SQ = $(subst ','\'',$(libdir))
+libdir_relative_SQ = $(subst ','\'',$(libdir_relative))
+
+TEST_ARGS := $(if $(V),-v)
+
+INCLUDES = \
+-I$(srctree)/tools/lib/perf/include \
+-I$(srctree)/tools/lib/ \
+-I$(srctree)/tools/include \
+-I$(srctree)/tools/arch/$(SRCARCH)/include/ \
+-I$(srctree)/tools/arch/$(SRCARCH)/include/uapi \
+-I$(srctree)/tools/include/uapi
+
+# Append required CFLAGS
+override CFLAGS := $(INCLUDES) $(CFLAGS)
+override CFLAGS += -g -Werror -Wall
+override CFLAGS += -fPIC
+override CFLAGS += -fvisibility=hidden
+override CFLAGS += $(EXTRA_WARNINGS)
+override CFLAGS += $(EXTRA_CFLAGS)
+
+all:
+
+export srctree OUTPUT CC LD CFLAGS V
+export DESTDIR DESTDIR_SQ
+
+include $(srctree)/tools/build/Makefile.include
+
+VERSION_SCRIPT := libperf.map
+
+PATCHLEVEL    = $(LIBPERF_PATCHLEVEL)
+EXTRAVERSION  = $(LIBPERF_EXTRAVERSION)
+VERSION       = $(LIBPERF_VERSION).$(LIBPERF_PATCHLEVEL).$(LIBPERF_EXTRAVERSION)
+
+LIBPERF_SO := $(OUTPUT)libperf.so.$(VERSION)
+LIBPERF_A  := $(OUTPUT)libperf.a
+LIBPERF_IN := $(OUTPUT)libperf-in.o
+LIBPERF_PC := $(OUTPUT)libperf.pc
+
+LIBPERF_ALL := $(LIBPERF_A) $(OUTPUT)libperf.so*
+
+LIB_DIR := $(srctree)/tools/lib/api/
+
+ifneq ($(OUTPUT),)
+ifneq ($(subdir),)
+  API_PATH=$(OUTPUT)/../lib/api/
+else
+  API_PATH=$(OUTPUT)
+endif
+else
+  API_PATH=$(LIB_DIR)
+endif
+
+LIBAPI = $(API_PATH)libapi.a
+export LIBAPI
+
+$(LIBAPI): FORCE
+	$(Q)$(MAKE) -C $(LIB_DIR) O=$(OUTPUT) $(OUTPUT)libapi.a
+
+$(LIBAPI)-clean:
+	$(call QUIET_CLEAN, libapi)
+	$(Q)$(MAKE) -C $(LIB_DIR) O=$(OUTPUT) clean >/dev/null
+
+$(LIBPERF_IN): FORCE
+	$(Q)$(MAKE) $(build)=libperf
+
+$(LIBPERF_A): $(LIBPERF_IN)
+	$(QUIET_AR)$(RM) $@ && $(AR) rcs $@ $(LIBPERF_IN)
+
+$(LIBPERF_SO): $(LIBPERF_IN) $(LIBAPI)
+	$(QUIET_LINK)$(CC) --shared -Wl,-soname,libperf.so \
+                                    -Wl,--version-script=$(VERSION_SCRIPT) $^ -o $@
+	@ln -sf $(@F) $(OUTPUT)libperf.so
+	@ln -sf $(@F) $(OUTPUT)libperf.so.$(LIBPERF_VERSION)
+
+
+libs: $(LIBPERF_A) $(LIBPERF_SO) $(LIBPERF_PC)
+
+all: fixdep
+	$(Q)$(MAKE) libs
+
+clean: $(LIBAPI)-clean
+	$(call QUIET_CLEAN, libperf) $(RM) $(LIBPERF_A) \
+                *.o *~ *.a *.so *.so.$(VERSION) *.so.$(LIBPERF_VERSION) .*.d .*.cmd tests/*.o LIBPERF-CFLAGS $(LIBPERF_PC) \
+                $(TESTS_STATIC) $(TESTS_SHARED)
+
+TESTS_IN = tests-in.o
+
+TESTS_STATIC = $(OUTPUT)tests-static
+TESTS_SHARED = $(OUTPUT)tests-shared
+
+$(TESTS_IN): FORCE
+	$(Q)$(MAKE) $(build)=tests
+
+$(TESTS_STATIC): $(TESTS_IN) $(LIBPERF_A) $(LIBAPI)
+	$(QUIET_LINK)$(CC) -o $@ $^
+
+$(TESTS_SHARED): $(TESTS_IN) $(LIBAPI)
+	$(QUIET_LINK)$(CC) -o $@ -L$(or $(OUTPUT),.) $^ -lperf
+
+make-tests: libs $(TESTS_SHARED) $(TESTS_STATIC)
+
+tests: make-tests
+	@echo "running static:"
+	@./$(TESTS_STATIC) $(TEST_ARGS)
+	@echo "running dynamic:"
+	@LD_LIBRARY_PATH=. ./$(TESTS_SHARED) $(TEST_ARGS)
+
+$(LIBPERF_PC):
+	$(QUIET_GEN)sed -e "s|@PREFIX@|$(prefix)|" \
+		-e "s|@LIBDIR@|$(libdir_SQ)|" \
+		-e "s|@VERSION@|$(VERSION)|" \
+		< libperf.pc.template > $@
+
+define do_install_mkdir
+	if [ ! -d '$(DESTDIR_SQ)$1' ]; then             \
+		$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$1'; \
+	fi
+endef
+
+define do_install
+	if [ ! -d '$2' ]; then             \
+		$(INSTALL) -d -m 755 '$2'; \
+	fi;                                \
+	$(INSTALL) $1 $(if $3,-m $3,) '$2'
+endef
+
+install_lib: libs
+	$(call QUIET_INSTALL, $(LIBPERF_ALL)) \
+		$(call do_install_mkdir,$(libdir_SQ)); \
+		cp -fpR $(LIBPERF_ALL) $(DESTDIR)$(libdir_SQ)
+
+HDRS := bpf_perf.h core.h cpumap.h threadmap.h evlist.h evsel.h event.h mmap.h
+HDRS += schedstat-v15.h schedstat-v16.h schedstat-v17.h
+INTERNAL_HDRS := cpumap.h evlist.h evsel.h lib.h mmap.h rc_check.h threadmap.h xyarray.h
+
+INSTALL_HDRS_PFX := $(DESTDIR)$(prefix)/include/perf
+INSTALL_HDRS := $(addprefix $(INSTALL_HDRS_PFX)/, $(HDRS))
+INSTALL_INTERNAL_HDRS_PFX := $(DESTDIR)$(prefix)/include/internal
+INSTALL_INTERNAL_HDRS := $(addprefix $(INSTALL_INTERNAL_HDRS_PFX)/, $(INTERNAL_HDRS))
+
+$(INSTALL_HDRS): $(INSTALL_HDRS_PFX)/%.h: include/perf/%.h
+	$(call QUIET_INSTALL, $@) \
+		$(call do_install,$<,$(INSTALL_HDRS_PFX)/,644)
+
+$(INSTALL_INTERNAL_HDRS): $(INSTALL_INTERNAL_HDRS_PFX)/%.h: include/internal/%.h
+	$(call QUIET_INSTALL, $@) \
+		$(call do_install,$<,$(INSTALL_INTERNAL_HDRS_PFX)/,644)
+
+install_headers: $(INSTALL_HDRS) $(INSTALL_INTERNAL_HDRS)
+	$(call QUIET_INSTALL, libperf_headers)
+
+install_pkgconfig: $(LIBPERF_PC)
+	$(call QUIET_INSTALL, $(LIBPERF_PC)) \
+		$(call do_install,$(LIBPERF_PC),$(DESTDIR_SQ)$(libdir_SQ)/pkgconfig,644)
+
+install_doc:
+	$(Q)$(MAKE) -C Documentation install-man install-html install-examples
+
+install: install_lib install_headers install_pkgconfig install_doc
+
+FORCE:
+
+.PHONY: all install clean tests FORCE