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, 78 insertions, 0 deletions

diff --git a/drivers/thunderbolt/Kconfig b/drivers/thunderbolt/Kconfig
new file mode 100644
index 000000000..294b3227a
--- /dev/null
+++ b/drivers/thunderbolt/Kconfig
@@ -0,0 +1,78 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menuconfig USB4
+	tristate "Unified support for USB4 and Thunderbolt"
+	depends on PCI
+	select APPLE_PROPERTIES if EFI_STUB && X86
+	select CRC32
+	select CRYPTO_LIB_SHA256
+	select CRYPTO_LIB_UTILS
+	select NVMEM
+	help
+	  USB4 and Thunderbolt driver. USB4 is the public specification
+	  based on the Thunderbolt 3 protocol. This driver is required if
+	  you want to hotplug Thunderbolt and USB4 compliant devices on
+	  Apple hardware or on PCs with Intel Falcon Ridge or newer.
+
+	  To compile this driver a module, choose M here. The module will be
+	  called thunderbolt.
+
+if USB4
+
+config USB4_CONFIGFS
+	def_tristate USB4
+	depends on CONFIGFS_FS && !(USB4=y && CONFIGFS_FS=m)
+
+config USB4_DEBUGFS_WRITE
+	bool "Enable write by debugfs to configuration spaces (DANGEROUS)"
+	help
+	  Enables writing to device configuration registers through
+	  debugfs interface. You can use tools such as Thunderbolt/USB4
+	  debugging tools to access these registers. For more
+	  information see:
+
+	    https://github.com/intel/tbtools
+
+	  Only enable this if you know what you are doing! Never enable
+	  this for production systems or distro kernels.
+
+config USB4_DEBUGFS_MARGINING
+	bool "Expose receiver lane margining operations under USB4 ports and retimers (DANGEROUS)"
+	depends on DEBUG_FS
+	depends on USB4_DEBUGFS_WRITE
+	help
+	  Enables hardware and software based receiver lane margining
+	  support under each USB4 port and retimer, including retimers
+	  on the other side of the cable. Used for electrical quality
+	  and robustness validation during manufacturing. Should not be
+	  enabled by distro kernels.
+
+config USB4_KUNIT_TEST
+	bool "KUnit tests" if !KUNIT_ALL_TESTS
+	depends on USB4 && KUNIT=y
+	default KUNIT_ALL_TESTS
+
+config USB4_DMA_TEST
+	tristate "DMA traffic test driver"
+	depends on DEBUG_FS
+	help
+	  This allows sending and receiving DMA traffic through loopback
+	  connection. Loopback connection can be done by either special
+	  dongle that has TX/RX lines crossed, or by simply connecting a
+	  cable back to the host. Only enable this if you know what you
+	  are doing. Normal users and distro kernels should say N here.
+
+	  To compile this driver a module, choose M here. The module will be
+	  called thunderbolt_dma_test.
+
+config USB4_STREAM
+	tristate "Stream data over Thunderbolt/USB4 cable"
+	depends on USB4_CONFIGFS
+	help
+	  This adds support for USB4STREAM protocol that allows two
+	  hosts to stream data directly over Thunderbolt/USB4 cable
+	  through /dev/tbstreamX devices.
+
+	  To compile this driver a module, choose M here. The module will be
+	  called thunderbolt_stream.
+
+endif # USB4