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, 27 insertions, 0 deletions

diff --git a/Documentation/driver-api/firmware/introduction.rst b/Documentation/driver-api/firmware/introduction.rst
new file mode 100644
index 000000000..211cb44eb
--- /dev/null
+++ b/Documentation/driver-api/firmware/introduction.rst
@@ -0,0 +1,27 @@
+============
+Introduction
+============
+
+The firmware API enables kernel code to request files required
+for functionality from userspace, the uses vary:
+
+* Microcode for CPU errata
+* Device driver firmware, required to be loaded onto device
+  microcontrollers
+* Device driver information data (calibration data, EEPROM overrides),
+  some of which can be completely optional.
+
+Types of firmware requests
+==========================
+
+There are two types of calls:
+
+* Synchronous
+* Asynchronous
+
+Which one you use vary depending on your requirements, the rule of thumb
+however is you should strive to use the asynchronous APIs unless you also
+are already using asynchronous initialization mechanisms which will not
+stall or delay boot. Even if loading firmware does not take a lot of time
+processing firmware might, and this can still delay boot or initialization,
+as such mechanisms such as asynchronous probe can help supplement drivers.