Subject: Re: [PATCH v7 07/10] iommu/dma-reserved-iommu: delete bindings in
 iommu_free_reserved_iova_domain
To: Robin Murphy <robin.murphy@arm.com>, eric.auger@st.com,
        alex.williamson@redhat.com, will.deacon@arm.com, joro@8bytes.org,
        tglx@linutronix.de, jason@lakedaemon.net, marc.zyngier@arm.com,
        christoffer.dall@linaro.org, linux-arm-kernel@lists.infradead.org
References: <1461084994-2355-1-git-send-email-eric.auger@linaro.org>
 <1461084994-2355-8-git-send-email-eric.auger@linaro.org>
 <5717B6D7.4010307@arm.com>
Cc: patches@linaro.org, linux-kernel@vger.kernel.org,
        Bharat.Bhushan@freescale.com, pranav.sawargaonkar@gmail.com,
        p.fedin@samsung.com, iommu@lists.linux-foundation.org,
        Jean-Philippe.Brucker@arm.com, julien.grall@arm.com
From: Eric Auger <eric.auger@linaro.org>
Message-ID: <57189211.7030802@linaro.org>
Date: Thu, 21 Apr 2016 10:40:49 +0200
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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@linaro.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);
>>
>