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, 77 insertions, 0 deletions

diff --git a/arch/xtensa/Makefile b/arch/xtensa/Makefile
new file mode 100644
index 000000000..4c14a0217
--- /dev/null
+++ b/arch/xtensa/Makefile
@@ -0,0 +1,77 @@
+#
+# This file is subject to the terms and conditions of the GNU General Public
+# License.  See the file "COPYING" in the main directory of this archive
+# for more details.
+#
+# Copyright (C) 2001 - 2005  Tensilica Inc.
+# Copyright (C) 2014 Cadence Design Systems Inc.
+#
+# This file is included by the global makefile so that you can add your own
+# architecture-specific flags and dependencies.
+
+# Core configuration.
+# (Use VAR=<xtensa_config> to use another default compiler.)
+
+variant-y := $(CONFIG_XTENSA_VARIANT_NAME)
+
+VARIANT = $(variant-y)
+
+ifneq ($(VARIANT),)
+  ifdef cross_compiling
+    ifndef CROSS_COMPILE
+      CROSS_COMPILE = xtensa_$(VARIANT)-
+    endif
+  endif
+endif
+
+# Platform configuration
+
+platform-$(CONFIG_XTENSA_PLATFORM_XT2000)	:= xt2000
+platform-$(CONFIG_XTENSA_PLATFORM_ISS)		:= iss
+platform-$(CONFIG_XTENSA_PLATFORM_XTFPGA)	:= xtfpga
+
+# temporarily until string.h is fixed
+KBUILD_CFLAGS += -ffreestanding -D__linux__
+KBUILD_CFLAGS += -pipe -mlongcalls -mtext-section-literals
+KBUILD_CFLAGS += $(call cc-option,-mforce-no-pic,)
+KBUILD_CFLAGS += $(call cc-option,-mno-serialize-volatile,)
+KBUILD_CFLAGS += $(call cc-option,-mno-fdpic,)
+ifneq ($(CONFIG_KERNEL_ABI_CALL0),)
+KBUILD_CFLAGS += -mabi=call0
+KBUILD_AFLAGS += -mabi=call0
+endif
+
+KBUILD_AFLAGS += -mlongcalls -mtext-section-literals
+KBUILD_AFLAGS += $(call cc-option,-mno-fdpic,)
+
+KBUILD_LDFLAGS += -m elf32xtensa
+
+ifneq ($(CONFIG_LD_NO_RELAX),)
+KBUILD_LDFLAGS += --no-relax
+endif
+
+CHECKFLAGS += -D$(if $(CONFIG_CPU_BIG_ENDIAN),__XTENSA_EB__,__XTENSA_EL__)
+
+vardirs := $(patsubst %,arch/xtensa/variants/%/,$(variant-y))
+plfdirs := $(patsubst %,arch/xtensa/platforms/%/,$(platform-y))
+
+KBUILD_CPPFLAGS += $(patsubst %,-I$(srctree)/%include,$(vardirs) $(plfdirs))
+
+KBUILD_DEFCONFIG := iss_defconfig
+
+libs-y		+= arch/xtensa/lib/
+
+boot		:= arch/xtensa/boot
+
+all Image zImage uImage xipImage: vmlinux
+	$(Q)$(MAKE) $(build)=$(boot) $@
+
+archheaders:
+	$(Q)$(MAKE) $(build)=arch/xtensa/kernel/syscalls all
+
+define archhelp
+  @echo '* Image       - Kernel ELF image with reset vector'
+  @echo '* zImage      - Compressed kernel image (arch/xtensa/boot/images/zImage.*)'
+  @echo '* uImage      - U-Boot wrapped image'
+  @echo '  xipImage    - XIP image'
+endef