Re: [PATCH] soc: ti: QMSS: Fix usage of irq_set_affinity_hint

[Florian Fainelli]

On 10/30/18 4:11 AM, Marc Zyngier wrote:
> The Keystone QMSS driver is pretty damaged, in the sense that it
> does things like this:
> 
> 	irq_set_affinity_hint(irq, to_cpumask(&cpu_map));
> 
> where cpu_map is a local variable. As we leave the function, this
> will point to nowhere-land, and things will end-up badly.
> 
> Instead, let's use a proper cpumask that gets allocated, giving
> the driver a chance to actually work with things like irqbalance
> as well as have a hypothetical 64bit future.

Since this is at least the second patch from you that I can see in this
area, would it make sense to sprinkle object_is_on_stack() checks
throughout irq_set_affinity_hint() to help catch offenders?

> 
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
> I found this one by inspection after finding a similar bug in an
> unrelated driver. It is only compile-tested. It would probably
> a Cc stable, but that's Santosh's decision.
> 
>  drivers/soc/ti/knav_qmss.h       |  4 ++--
>  drivers/soc/ti/knav_qmss_acc.c   | 10 +++++-----
>  drivers/soc/ti/knav_qmss_queue.c | 22 +++++++++++++++-------
>  3 files changed, 22 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/soc/ti/knav_qmss.h b/drivers/soc/ti/knav_qmss.h
> index 3efc47e82973..bd040c29c4bf 100644
> --- a/drivers/soc/ti/knav_qmss.h
> +++ b/drivers/soc/ti/knav_qmss.h
> @@ -329,8 +329,8 @@ struct knav_range_ops {
>  };
>  
>  struct knav_irq_info {
> -	int	irq;
> -	u32	cpu_map;
> +	int		irq;
> +	struct cpumask	*cpu_mask;
>  };
>  
>  struct knav_range_info {
> diff --git a/drivers/soc/ti/knav_qmss_acc.c b/drivers/soc/ti/knav_qmss_acc.c
> index 316e82e46f6c..2f7fb2dcc1d6 100644
> --- a/drivers/soc/ti/knav_qmss_acc.c
> +++ b/drivers/soc/ti/knav_qmss_acc.c
> @@ -205,18 +205,18 @@ static int knav_range_setup_acc_irq(struct knav_range_info *range,
>  {
>  	struct knav_device *kdev = range->kdev;
>  	struct knav_acc_channel *acc;
> -	unsigned long cpu_map;
> +	struct cpumask *cpu_mask;
>  	int ret = 0, irq;
>  	u32 old, new;
>  
>  	if (range->flags & RANGE_MULTI_QUEUE) {
>  		acc = range->acc;
>  		irq = range->irqs[0].irq;
> -		cpu_map = range->irqs[0].cpu_map;
> +		cpu_mask = range->irqs[0].cpu_mask;
>  	} else {
>  		acc = range->acc + queue;
>  		irq = range->irqs[queue].irq;
> -		cpu_map = range->irqs[queue].cpu_map;
> +		cpu_mask = range->irqs[queue].cpu_mask;
>  	}
>  
>  	old = acc->open_mask;
> @@ -239,8 +239,8 @@ static int knav_range_setup_acc_irq(struct knav_range_info *range,
>  			acc->name, acc->name);
>  		ret = request_irq(irq, knav_acc_int_handler, 0, acc->name,
>  				  range);
> -		if (!ret && cpu_map) {
> -			ret = irq_set_affinity_hint(irq, to_cpumask(&cpu_map));
> +		if (!ret && cpu_mask) {
> +			ret = irq_set_affinity_hint(irq, cpu_mask);
>  			if (ret) {
>  				dev_warn(range->kdev->dev,
>  					 "Failed to set IRQ affinity\n");
> diff --git a/drivers/soc/ti/knav_qmss_queue.c b/drivers/soc/ti/knav_qmss_queue.c
> index b5d5673c255c..8b418379272d 100644
> --- a/drivers/soc/ti/knav_qmss_queue.c
> +++ b/drivers/soc/ti/knav_qmss_queue.c
> @@ -118,19 +118,17 @@ static int knav_queue_setup_irq(struct knav_range_info *range,
>  			  struct knav_queue_inst *inst)
>  {
>  	unsigned queue = inst->id - range->queue_base;
> -	unsigned long cpu_map;
>  	int ret = 0, irq;
>  
>  	if (range->flags & RANGE_HAS_IRQ) {
>  		irq = range->irqs[queue].irq;
> -		cpu_map = range->irqs[queue].cpu_map;
>  		ret = request_irq(irq, knav_queue_int_handler, 0,
>  					inst->irq_name, inst);
>  		if (ret)
>  			return ret;
>  		disable_irq(irq);
> -		if (cpu_map) {
> -			ret = irq_set_affinity_hint(irq, to_cpumask(&cpu_map));
> +		if (range->irqs[queue].cpu_mask) {
> +			ret = irq_set_affinity_hint(irq, range->irqs[queue].cpu_mask);
>  			if (ret) {
>  				dev_warn(range->kdev->dev,
>  					 "Failed to set IRQ affinity\n");
> @@ -1262,9 +1260,19 @@ static int knav_setup_queue_range(struct knav_device *kdev,
>  
>  		range->num_irqs++;
>  
> -		if (IS_ENABLED(CONFIG_SMP) && oirq.args_count == 3)
> -			range->irqs[i].cpu_map =
> -				(oirq.args[2] & 0x0000ff00) >> 8;
> +		if (IS_ENABLED(CONFIG_SMP) && oirq.args_count == 3) {
> +			unsigned long mask;
> +			int bit;
> +
> +			range->irqs[i].cpu_mask = devm_kzalloc(dev,
> +							       cpumask_size(), GFP_KERNEL);
> +			if (!range->irqs[i].cpu_mask)
> +				return -ENOMEM;
> +
> +			mask = (oirq.args[2] & 0x0000ff00) >> 8;
> +			for_each_set_bit(bit, &mask, BITS_PER_LONG)
> +				cpumask_set_cpu(bit, range->irqs[i].cpu_mask);
> +		}
>  	}
>  
>  	range->num_irqs = min(range->num_irqs, range->num_queues);
> 


-- 
Florian