| Message ID | 1455632084-14666-1-git-send-email-m.szyprowski@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
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? Robin. > return ret; > } > arch_initcall(__iommu_dma_init); >
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
On 17/02/16 07:06, Marek Szyprowski wrote: > 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. Ok, fair enough - I guess I just didn't consider that being a likely possibility. Since I am a fan of correctness: Acked-by: Robin Murphy <robin.murphy@arm.com> Thanks, Robin. > > Best regards
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); return ret; } arch_initcall(__iommu_dma_init);
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(+)