Hello Bartosz, On Thu, Nov 08, 2018 at 05:47:48PM +0100, Bartosz Golaszewski wrote: > Two threads can try to fire the irq_sim with different offsets and will > end up fighting for the irq_work asignment. To fix it: add a mutex and > lock it before firing. > > Suggested-by: Uwe Kleine-König <u.kleine-koe...@pengutronix.de> > Signed-off-by: Bartosz Golaszewski <b...@bgdev.pl> > --- > include/linux/irq_sim.h | 1 + > kernel/irq/irq_sim.c | 5 +++++ > 2 files changed, 6 insertions(+) > > diff --git a/include/linux/irq_sim.h b/include/linux/irq_sim.h > index 630a57e55db6..676bfa0c12b9 100644 > --- a/include/linux/irq_sim.h > +++ b/include/linux/irq_sim.h > @@ -29,6 +29,7 @@ struct irq_sim { > int irq_base; > unsigned int irq_count; > struct irq_sim_irq_ctx *irqs; > + struct mutex lock; > }; > > int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs); > diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c > index dd20d0d528d4..2f06c24b51a0 100644 > --- a/kernel/irq/irq_sim.c > +++ b/kernel/irq/irq_sim.c > @@ -74,6 +74,7 @@ int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs) > } > > init_irq_work(&sim->work_ctx.work, irq_sim_handle_irq); > + mutex_init(&sim->lock); > sim->irq_count = num_irqs; > > return sim->irq_base; > @@ -142,10 +143,14 @@ EXPORT_SYMBOL_GPL(devm_irq_sim_init); > */ > void irq_sim_fire(struct irq_sim *sim, unsigned int offset) > { > + mutex_lock(&sim->lock); > + > if (sim->irqs[offset].enabled) { > sim->work_ctx.irq = irq_sim_irqnum(sim, offset); > irq_work_queue(&sim->work_ctx.work); > } > + > + mutex_unlock(&sim->lock);
This doesn't fix the issue I think. irq_work_queue() only schedules the work function. If after irq_sim_fire() returned but before the worker runs another irq_sim_fire() is issued the value is still overwritten. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |