| From: |
| Sebastian Andrzej Siewior <bigeasy-AT-linutronix.de> |
| To: |
| linux-rt-devel-AT-lists.linux.dev, linux-kernel-AT-vger.kernel.org |
| Subject: |
| [PATCH v3 0/3] Allow to drop the softirq-BKL lock on PREEMPT_RT |
| Date: |
| Thu, 04 Sep 2025 16:25:22 +0200 |
| Message-ID: |
| <20250904142526.1845999-1-bigeasy@linutronix.de> |
| Cc: |
| Clark Williams <clrkwllms-AT-kernel.org>, Ingo Molnar <mingo-AT-redhat.com>, Lai Jiangshan <jiangshanlai-AT-gmail.com>, Peter Zijlstra <peterz-AT-infradead.org>, Steven Rostedt <rostedt-AT-goodmis.org>, Tejun Heo <tj-AT-kernel.org>, Thomas Gleixner <tglx-AT-linutronix.de>, Sebastian Andrzej Siewior <bigeasy-AT-linutronix.de> |
| Archive-link: |
| Article |
Users which rely on synchronisation within a BH-disabled section as in
- access to per-CPU data
- per-CPU timers
- synchronisation against another user within a BH-disabled section
rely on the local_lock_t lock in local_bh_disable() on PREEMPT_RT.
Almost all users dropped their dependency. The remaining (identified)
user in networking (pipapo) is in net-next.
What is left is the infrastructure as in tasklet and workqueue (for
bh-worker).
Both are part of this series. The last patch in the series adds an
option to drop the lock.
v1…v2: https://lore.kernel.org/all/20250901163811.963326-1-bigea...
- In workqueue, __flush_work(), replace wq_pool_mutex with RCU locking.
v1 tasklet https://lore.kernel.org/all/20250812143930.22RBn5BW@linut...
v1 workqueue https://lore.kernel.org/all/20250820103657.vDuDuLx6@linut...
v1 lock-drop https://lore.kernel.org/all/20250613105653.1860729-2-bige...
Sebastian Andrzej Siewior (3):
workqueue: Provide a handshake for canceling BH workers
softirq: Provide a handshake for canceling tasklets via polling
softirq: Allow to drop the softirq-BKL lock on PREEMPT_RT
kernel/Kconfig.preempt | 13 ++++
kernel/softirq.c | 145 ++++++++++++++++++++++++++++++++++-------
kernel/workqueue.c | 50 +++++++++++---
3 files changed, 174 insertions(+), 34 deletions(-)
--
2.51.0
