Hi Aniruddha,
On 26/03/18 13:02, Aniruddha Banerjee wrote:
> The kernel documentation states that the locking of the irq-chip
> registers should be handled by the irq-chip driver. In the irq-gic,
> the accesses to the irqchip are seemingly not protected and multiple
> writes to SPIs from different irq descriptors do RMW requests without
> taking the irq-chip lock. When multiple irqs call the request_irq at
> the same time, there can be a simultaneous write at the gic
> distributor, leading to a race. Acquire the gic_lock when the
> irq_type is updated.
>
> Signed-off-by: Aniruddha Banerjee <aniruddhab@xxxxxxxxxx>
> ---
> drivers/irqchip/irq-gic.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/irqchip/irq-gic.c b/drivers/irqchip/irq-gic.c
> index 4c797b43614d..61380f5a2254 100644
> --- a/drivers/irqchip/irq-gic.c
> +++ b/drivers/irqchip/irq-gic.c
> @@ -67,6 +67,8 @@ static void gic_check_cpu_features(void)
> #define gic_check_cpu_features() do { } while(0)
> #endif
>
> +static DEFINE_RAW_SPINLOCK(irq_controller_lock);
> +
> union gic_base {
> void __iomem *common_base;
> void __percpu * __iomem *percpu_base;
> @@ -529,6 +531,7 @@ static int gic_set_type(struct irq_data *d, unsigned int type)
> {
> void __iomem *base = gic_dist_base(d);
> unsigned int gicirq = gic_irq(d);
> + int ret;
>
> /* Interrupt configuration for SGIs can't be changed */
> if (gicirq < 16)
> @@ -539,7 +542,11 @@ static int gic_set_type(struct irq_data *d, unsigned int type)
> type != IRQ_TYPE_EDGE_RISING)
> return -EINVAL;
>
> - return gic_configure_irq(gicirq, type, base, NULL);
> + raw_spin_lock(&irq_controller_lock);
> + ret = gic_configure_irq(gicirq, type, base, NULL);
> + raw_spin_unlock(&irq_controller_lock);
> +
> + return ret;
> }
>
> static int gic_irq_set_vcpu_affinity(struct irq_data *d, void *vcpu)
>
You do have a good point here, but it'd be better to put it directly in
the gic_configure_irq() function, fixing both GICv1/2 and v3 in one go.
That would allow the sync_access method to be run outside of the
critical section.
Please post it to LKML and add a Cc stable for it.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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