On Mon, 18 Sep 2023 13:24:11 +0100,
Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
>
> In case of edge trigger detection, enabling the TINT source causes a
> phantum interrupt that leads to irq storm. So clear the phantum interrupt
> in rzg2l_irqc_irq_enable().
>
> This issue is observed when the irq handler disables the interrupts using
> disable_irq_nosync() and scheduling a work queue and in the work queue,
> re-enabling the interrupt with enable_irq().
>
> Fixes: 3fed09559cd8 ("irqchip: Add RZ/G2L IA55 Interrupt Controller driver")
> Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> Tested-by: Claudiu Beznea <claudiu.beznea.uj@xxxxxxxxxxxxxx>
> ---
> drivers/irqchip/irq-renesas-rzg2l.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/irqchip/irq-renesas-rzg2l.c b/drivers/irqchip/irq-renesas-rzg2l.c
> index 33a22bafedcd..78a9e90512a6 100644
> --- a/drivers/irqchip/irq-renesas-rzg2l.c
> +++ b/drivers/irqchip/irq-renesas-rzg2l.c
> @@ -144,6 +144,12 @@ static void rzg2l_irqc_irq_enable(struct irq_data *d)
> reg = readl_relaxed(priv->base + TSSR(tssr_index));
> reg |= (TIEN | tint) << TSSEL_SHIFT(tssr_offset);
> writel_relaxed(reg, priv->base + TSSR(tssr_index));
> + /*
> + * In case of edge trigger detection, enabling the TINT source
> + * cause a phantum interrupt that leads to irq storm. So clear
> + * the phantum interrupt.
> + */
> + rzg2l_tint_eoi(d);
This looks incredibly unsafe. disable_irq()+enable_irq() with an
interrupt being made pending in the middle, and you've lost that
interrupt.
What prevents this scenario?
M.
--
Without deviation from the norm, progress is not possible.
