From: m.szyprowski@samsung•com (Marek Szyprowski)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] ARM64: dma-mapping: fix handling of devices registered before arch_initcall
Date: Wed, 17 Feb 2016 08:06:14 +0100 [thread overview]
Message-ID: <56C41BE6.5000203@samsung.com> (raw)
In-Reply-To: <56C37317.9020104@arm.com>
Hello,
On 2016-02-16 20:05, Robin Murphy wrote:
> On 16/02/16 14:14, Marek Szyprowski wrote:
>> This patch ensures that devices, which got registered before
>> arch_initcall
>> will be handled correctly by IOMMU-based DMA-mapping code.
>>
>> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung•com>
>> ---
>> arch/arm64/mm/dma-mapping.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
>> index 573b1e6..ce6019f 100644
>> --- a/arch/arm64/mm/dma-mapping.c
>> +++ b/arch/arm64/mm/dma-mapping.c
>> @@ -928,6 +928,10 @@ static int __init __iommu_dma_init(void)
>> ret = register_iommu_dma_ops_notifier(&platform_bus_type);
>> if (!ret)
>> ret = register_iommu_dma_ops_notifier(&amba_bustype);
>> +
>> + /* handle devices queued before this arch_initcall */
>> + if (!ret)
>> + __iommu_attach_notifier(NULL, BUS_NOTIFY_ADD_DEVICE, NULL);
>
> Hmm, surely unless *all* the devices on the relevant buses are created
> before arch_initcall level, then the next one is going to kick off the
> notifier to walk the whole list anyway. Have you seen this being a
> problem in practice?
Yes, I've observed such situation, that's why I've posted this patch. I was
really surprised that this code doesn't handle all cases.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
next prev parent reply other threads:[~2016-02-17 7:06 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-16 14:14 [PATCH] ARM64: dma-mapping: fix handling of devices registered before arch_initcall Marek Szyprowski
2016-02-16 19:05 ` Robin Murphy
2016-02-17 7:06 ` Marek Szyprowski [this message]
2016-02-17 10:19 ` Robin Murphy
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