On Fri, 25 Mar 2011, David Daney wrote:
> The .irq_cpu_online() and .irq_cpu_offline() functions may need to
> adjust affinity, but they are called with the descriptor lock held.
> Create __irq_set_affinity_locked() which is called with the lock held.
> Make irq_set_affinity() just a wrapper that acquires the lock.
>
> Signed-off-by: David Daney <ddaney@xxxxxxxxxxxxxxxxxx>
> ---
> include/linux/interrupt.h | 2 ++
> kernel/irq/manage.c | 40 ++++++++++++++++++++++++++--------------
> 2 files changed, 28 insertions(+), 14 deletions(-)
>
> diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
> index 59b72ca..815f9fb 100644
> --- a/include/linux/interrupt.h
> +++ b/include/linux/interrupt.h
> @@ -229,6 +229,8 @@ static inline int check_wakeup_irqs(void) { return 0; }
> extern cpumask_var_t irq_default_affinity;
>
> extern int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask);
> +extern int __irq_set_affinity_locked(struct irq_desc *desc,
> + const struct cpumask *cpumask);
> extern int irq_can_set_affinity(unsigned int irq);
> extern int irq_select_affinity(unsigned int irq);
>
> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
> index 0a2aa73..3d3bed1 100644
> --- a/kernel/irq/manage.c
> +++ b/kernel/irq/manage.c
> @@ -139,24 +139,12 @@ static inline void
> irq_get_pending(struct cpumask *mask, struct irq_desc *desc) { }
> #endif
>
> -/**
> - * irq_set_affinity - Set the irq affinity of a given irq
> - * @irq: Interrupt to set affinity
> - * @cpumask: cpumask
> - *
> - */
> -int irq_set_affinity(unsigned int irq, const struct cpumask *mask)
> +
> +int __irq_set_affinity_locked(struct irq_desc *desc, const struct cpumask *mask)
> {
> - struct irq_desc *desc = irq_to_desc(irq);
> struct irq_chip *chip = desc->irq_data.chip;
> - unsigned long flags;
> int ret = 0;
>
> - if (!chip->irq_set_affinity)
> - return -EINVAL;
We want to keep that check here. No need to crash with a NULL pointer
dereference, when we can deal with it gracefully.
Thanks,
tglx
