linux-kernel - Re: [PATCH] soc: ti: QMSS: Fix usage of irq_set_affinity

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Date:   Tue, 30 Oct 2018 10:18:08 -0700
From:   Santosh Shilimkar <santosh.shilimkar@...cle.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Marc Zyngier <marc.zyngier@....com>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] soc: ti: QMSS: Fix usage of irq_set_affinity_hint

Hi Greg,

On 10/30/2018 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.
> 
> Signed-off-by: Marc Zyngier <marc.zyngier@....com>
> ---
> 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.

Would be able to apply this fix from Marc for stable or it needs
to be re-posted with CC to stable ?

> 
>   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);
>