linux-kernel - Re: [PATCH v7 07/10] iommu/dma-reserved-iommu: delete bindings in iommu_free_reserved_iova

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Date:	Thu, 21 Apr 2016 10:40:49 +0200
From:	Eric Auger <eric.auger@...aro.org>
To:	Robin Murphy <robin.murphy@....com>, eric.auger@...com,
	alex.williamson@...hat.com, will.deacon@....com, joro@...tes.org,
	tglx@...utronix.de, jason@...edaemon.net, marc.zyngier@....com,
	christoffer.dall@...aro.org, linux-arm-kernel@...ts.infradead.org
Cc:	patches@...aro.org, linux-kernel@...r.kernel.org,
	Bharat.Bhushan@...escale.com, pranav.sawargaonkar@...il.com,
	p.fedin@...sung.com, iommu@...ts.linux-foundation.org,
	Jean-Philippe.Brucker@....com, julien.grall@....com
Subject: Re: [PATCH v7 07/10] iommu/dma-reserved-iommu: delete bindings in
 iommu_free_reserved_iova_domain

Hi,
On 04/20/2016 07:05 PM, Robin Murphy wrote:
> On 19/04/16 17:56, Eric Auger wrote:
>> Now reserved bindings can exist, destroy them when destroying
>> the reserved iova domain. iommu_map is not supposed to be atomic,
>> hence the extra complexity in the locking.
>>
>> Signed-off-by: Eric Auger <eric.auger@...aro.org>
>>
>> ---
>> v6 -> v7:
>> - remove [PATCH v6 7/7] dma-reserved-iommu: iommu_unmap_reserved and
>>    destroy the bindings in iommu_free_reserved_iova_domain
>>
>> v5 -> v6:
>> - use spin_lock instead of mutex
>>
>> v3 -> v4:
>> - previously "iommu/arm-smmu: relinquish reserved resources on
>>    domain deletion"
>> ---
>>   drivers/iommu/dma-reserved-iommu.c | 34
>> ++++++++++++++++++++++++++++------
>>   1 file changed, 28 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/iommu/dma-reserved-iommu.c
>> b/drivers/iommu/dma-reserved-iommu.c
>> index 426d339..2522235 100644
>> --- a/drivers/iommu/dma-reserved-iommu.c
>> +++ b/drivers/iommu/dma-reserved-iommu.c
>> @@ -157,14 +157,36 @@ void iommu_free_reserved_iova_domain(struct
>> iommu_domain *domain)
>>       unsigned long flags;
>>       int ret = 0;
>>
>> -    spin_lock_irqsave(&domain->reserved_lock, flags);
>> -
>> -    rid = (struct reserved_iova_domain *)domain->reserved_iova_cookie;
>> -    if (!rid) {
>> -        ret = -EINVAL;
>> -        goto unlock;
>> +    while (1) {
>> +        struct iommu_reserved_binding *b;
>> +        struct rb_node *node;
>> +        dma_addr_t iova;
>> +        size_t size;
>> +
>> +        spin_lock_irqsave(&domain->reserved_lock, flags);
>> +
>> +        rid = (struct reserved_iova_domain *)
>> +                domain->reserved_iova_cookie;
> 
> Same comment about casting as before.
OK
> 
>> +        if (!rid) {
>> +            ret = -EINVAL;
>> +            goto unlock;
>> +        }
>> +
>> +        node = rb_first(&domain->reserved_binding_list);
>> +        if (!node)
>> +            break;
>> +        b = rb_entry(node, struct iommu_reserved_binding, node);
>> +
>> +        iova = b->iova;
>> +        size = b->size;
>> +
>> +        while (!kref_put(&b->kref, reserved_binding_release))
>> +            ;
> 
> Since you're freeing the thing anyway, why not just call the function
> directly?
makes sense indeed.

Thanks

Eric
> 
>> +        spin_unlock_irqrestore(&domain->reserved_lock, flags);
>> +        iommu_unmap(domain, iova, size);
>>       }
>>
>> +    domain->reserved_binding_list = RB_ROOT;
>>       domain->reserved_iova_cookie = NULL;
>>   unlock:
>>       spin_unlock_irqrestore(&domain->reserved_lock, flags);
>>
>