RCU changes for v6.16

[Joel Fernandes <joelagnelf@nvidia.com>]

Hi Linus,

When the merge window opens, please pull the RCU changes for v6.16:

The following changes since commit 0af2f6be1b4281385b618cb86ad946eded089ac8:

  Linux 6.15-rc1 (2025-04-06 13:11:33 -0700)

are available in the Git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux.git tags/next.2025.05.17a

for you to fetch changes up to 9c80e443379861a6b374db3c5bb830167cbe0676:

  Merge branches 'rcu/misc-for-6.16', 'rcu/seq-counters-for-6.16' and
  'rcu/torture-for-6.16' into rcu/for-next (2025-05-16 11:18:16 -0400)

We in the RCU maintainers crew have done rigorous testing of these patches on
both x86 and ARM, big and small machines, to ensure high quality so I am
confident this will go smoothly. Thanks!

----------------------------------------------------------------
RCU pull request for v6.16

Summary of changes:
- Removed swake_up_one_online() workaround
- Reverted an incorrect rcuog wake-up fix from offline softirq
- Rust RCU Guard methods marked as inline
- Updated MAINTAINERS with Joel’s and Zqiang's new email address
- Replaced magic constant in rcu_seq_done_exact() with named constant
- Added warning mechanism to validate rcu_seq_done_exact()
- Switched SRCU polling API to use rcu_seq_done_exact()
- Commented on redundant delta check in rcu_seq_done_exact()
- Made ->gpwrap tests in rcutorture more frequent
- Fixed reuse of ARM64 images in rcutorture
- rcutorture improved to check Kconfig and reader conflict handling
- Extracted logic from rcu_torture_one_read() for clarity
- Updated LWN RCU API documentation links
- Enabled --do-rt in torture.sh for CONFIG_PREEMPT_RT
- Added tests for SRCU up/down reader primitives
- Added comments and delays checks in rcutorture
- Deprecated srcu_read_lock_lite() and srcu_read_unlock_lite() via checkpatch
- Added --do-normal and --do-no-normal to torture.sh
- Added RCU Rust binding tests to torture.sh
- Reduced CPU overcommit and removed MAXSMP/CPUMASK_OFFSTACK in TREE01
- Replaced kmalloc() with kcalloc() in rcuscale
- Refined listRCU example code for stale data elimination
- Fixed hardirq count bug for x86 in cpu_stall_cputime
- Added safety checks in rcu/nocb for offloaded rdp access
- Other miscellaneous changes

----------------------------------------------------------------
Frederic Weisbecker (3):
      rcu: Comment on the extraneous delta test on rcu_seq_done_exact()
      rcu: Remove swake_up_one_online() bandaid
      Revert "rcu/nocb: Fix rcuog wake-up from offline softirq"

I Hsin Cheng (1):
      rust: sync: rcu: Mark Guard methods as inline

Joel Fernandes (7):
      MAINTAINERS: Update Joel's email address
      rcu: Replace magic number with meaningful constant in rcu_seq_done_exact()
      rcu: Add warning to ensure rcu_seq_done_exact() is working
      srcu: Use rcu_seq_done_exact() for polling API
      rcutorture: Perform more frequent testing of ->gpwrap
      rcutorture: Fix issue with re-using old images on ARM64
      Merge branches 'rcu/misc-for-6.16', 'rcu/seq-counters-for-6.16' and 'rcu/torture-for-6.16' into rcu/for-next

Paul E. McKenney (12):
      rcutorture: Make srcu_lockdep.sh check kernel Kconfig
      rcutorture: Make srcu_lockdep.sh check reader-conflict handling
      rcutorture: Split out beginning and end from rcu_torture_one_read()
      rcutorture: Make torture.sh --do-rt use CONFIG_PREEMPT_RT
      doc: Update LWN RCU API links in whatisRCU.rst
      rcutorture: Comment invocations of tick_dep_set_task()
      checkpatch: Deprecate srcu_read_lock_lite() and srcu_read_unlock_lite()
      torture: Add --do-{,no-}normal to torture.sh
      torture: Add testing of RCU's Rust bindings to torture.sh
      torture: Check for "Call trace:" as well as "Call Trace:"
      rcutorture: Reduce TREE01 CPU overcommit
      rcutorture: Remove MAXSMP and CPUMASK_OFFSTACK from TREE01

Su Hui (1):
      rcuscale: using kcalloc() to relpace kmalloc()

Wei Yang (1):
      doc/RCU/listRCU: refine example code for eliminating stale data

Yongliang Gao (1):
      rcu/cpu_stall_cputime: fix the hardirq count for x86 architecture

Zqiang (2):
      MAINTAINERS: Update Zqiang's email address
      rcu/nocb: Add Safe checks for access offloaded rdp

 Documentation/RCU/listRCU.rst                      |  10 +-
 Documentation/RCU/whatisRCU.rst                    |   3 +
 Documentation/admin-guide/kernel-parameters.txt    |  25 +++
 MAINTAINERS                                        |   8 +-
 kernel/rcu/rcu.h                                   |  18 +-
 kernel/rcu/rcuscale.c                              |   2 +-
 kernel/rcu/rcutorture.c                            | 206 ++++++++++++++++-----
 kernel/rcu/srcutree.c                              |   2 +-
 kernel/rcu/tree.c                                  |  84 +++++----
 kernel/rcu/tree.h                                  |   3 +-
 kernel/rcu/tree_exp.h                              |   2 +-
 kernel/rcu/tree_nocb.h                             |  10 +-
 kernel/rcu/tree_plugin.h                           |   2 +-
 kernel/rcu/tree_stall.h                            |   4 +-
 rust/kernel/sync/rcu.rs                            |   5 +
 scripts/checkpatch.pl                              |   2 +
 .../selftests/rcutorture/bin/console-badness.sh    |   2 +-
 .../selftests/rcutorture/bin/kvm-test-1-run.sh     |   2 +-
 .../selftests/rcutorture/bin/parse-console.sh      |   2 +-
 .../selftests/rcutorture/bin/srcu_lockdep.sh       |  42 ++++-
 tools/testing/selftests/rcutorture/bin/torture.sh  |  89 ++++++++-
 .../selftests/rcutorture/configs/rcu/TREE01        |   2 -
 .../selftests/rcutorture/configs/rcu/TREE01.boot   |   2 +-
 23 files changed, 403 insertions(+), 124 deletions(-)