Messages in this thread | | | Date | Fri, 9 Nov 2018 11:19:16 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] irq/irq_sim: add locking |
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On Thu, 8 Nov 2018, Uwe Kleine-König wrote: > On Thu, Nov 08, 2018 at 05:47:48PM +0100, Bartosz Golaszewski wrote: > > @@ -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.
Right. So the obvious solution is to avoid the irq number store and use a bitfield instead.
struct irq_sim_work_ctx { ... unsigned long pending; };
fire(sim, offset) { if (!sim->irqs[offset].enabled) return;
set_bit(offset, &sim->work_ctx.pending); ....
and in the work handler do:
handle(work) { struct irq_sim_work_ctx *ctx = container_of(work,....);
while (ctx->pending) { offs = ffs(ctx->pending); clr_bit(offs, &ctx->pending); handle_simple_irq(offs); } }
Or something like that.
Thanks,
tglx | |