Re: [RFC PATCH 06/33] irqchip/gic-v3-its: Add probing for VLPI properties

From: Thomas Gleixner
Date: Mon Feb 13 2017 - 05:00:50 EST


On Tue, 17 Jan 2017, Marc Zyngier wrote:
> + typer = gic_read_typer(its_base + GITS_TYPER);
> its->base = its_base;
> its->phys_base = res->start;
> - its->ite_size = ((gic_read_typer(its_base + GITS_TYPER) >> 4) & 0xf) + 1;
> + its->ite_size = ((typer >> 4) & 0xf) + 1;
> + its->is_v4 = !!(typer & GITS_TYPER_VLPIS);
> + if (its->is_v4 && !(typer & GITS_TYPER_VMOVP)) {
> + int its_number;
> +
> + its_number = find_first_zero_bit(&its_list_map, 16);

s/16/ITS_MAX_ENTITIES or whatever.

> + if (its_number >= 16) {
> + pr_err("ITS@%pa: No ITSList entry available!\n",
> + &res->start);
> + err = -EINVAL;
> + goto out_free_its;
> + }
> +
> + ctlr = readl_relaxed(its_base + GITS_CTLR);
> + ctlr &= ~GITS_CTLR_ITS_NUMBER;
> + ctlr |= its_number << GITS_CTLR_ITS_NUMBER_SHIFT;
> + writel_relaxed(ctlr, its_base + GITS_CTLR);
> + ctlr = readl_relaxed(its_base + GITS_CTLR);
> + if ((ctlr & GITS_CTLR_ITS_NUMBER) != (its_number << GITS_CTLR_ITS_NUMBER_SHIFT)) {
> + its_number = ctlr & GITS_CTLR_ITS_NUMBER;
> + its_number >>= GITS_CTLR_ITS_NUMBER_SHIFT;
> + }
> +
> + if (test_and_set_bit(its_number, &its_list_map)) {

You just established above that the bit is not set. I assume that this is
code which has no concurrency concerns....

Thanks,

tglx