github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-11-06 21:58:01 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

srcu: Use IRQ_WORK_INIT_HARD for srcu's irq_work

Browse Source 
The irq_work in srcu is used to schedule a delayed work. The work item
is not scheduled directly because it is not always possible wake a
thread directly.

On PREEMPT_RT the default irq_work is initialized with IRQ_WORK_LAZY and
is delayed to the irq_work thread. A system booted with the command line
"trace_event=…" will freeze during boot because the irq_work thread is
not yet deployed (and tracing uses synchronize_srcu() in
tp_rcu_cond_sync()).

The irq_work performs just a wakeup a thread, there is nothing wrong
with doing this from hardirq context on PREEMPT_RT.

Use IRQ_WORK_INIT_HARD for srcu's irq_work.

Fixes: 7c405fb327 ("rcu: Use an intermediate irq_work to start process_srcu()")
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Sebastian Andrzej Siewior 2026-08-21 20:38:09 +02:00 committed by Paul E. McKenney
parent 18c55d888b
commit f8d9588809
1 changed files with 6 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
kernel/rcu/srcutree.c
View File

@ -259,7 +259,12 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static, bool
mutex_init(&ssp->srcu_sup->srcu_barrier_mutex);
atomic_set(&ssp->srcu_sup->srcu_barrier_cpu_cnt, 0);
INIT_DELAYED_WORK(&ssp->srcu_sup->work, process_srcu);
init_irq_work(&ssp->srcu_sup->irq_work, srcu_irq_work);
/*
* trace events started on the command line require SRCU before
* the irq_work kthread starts. Since all it does is a simple
* wakeup, having it as a hard irq, even on PREEMPT_RT is fine.
*/
ssp->srcu_sup->irq_work = IRQ_WORK_INIT_HARD(srcu_irq_work);
ssp->srcu_sup->sda_is_static = is_static;
if (!is_static) {
ssp->sda = alloc_percpu(struct srcu_data);