Messages in this thread | | | Date | Wed, 23 Oct 2019 17:52:53 +0100 | From | Will Deacon <> | Subject | Re: [PATCH v4 2/7] iommu/mediatek: Add a new tlb_lock for tlb_flush |
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On Wed, Oct 16, 2019 at 11:33:07AM +0800, Yong Wu wrote: > The commit 4d689b619445 ("iommu/io-pgtable-arm-v7s: Convert to IOMMU API > TLB sync") help move the tlb_sync of unmap from v7s into the iommu > framework. It helps add a new function "mtk_iommu_iotlb_sync", But it > lacked the lock, then it will cause the variable "tlb_flush_active" > may be changed unexpectedly, we could see this warning log randomly: > > mtk-iommu 10205000.iommu: Partial TLB flush timed out, falling back to > full flush > > The HW requires tlb_flush/tlb_sync in pairs strictly, this patch adds > a new tlb_lock for tlb operations to fix this issue. > > Fixes: 4d689b619445 ("iommu/io-pgtable-arm-v7s: Convert to IOMMU API TLB > sync") > Signed-off-by: Yong Wu <yong.wu@mediatek.com> > --- > drivers/iommu/mtk_iommu.c | 23 ++++++++++++++++++++++- > drivers/iommu/mtk_iommu.h | 1 + > 2 files changed, 23 insertions(+), 1 deletion(-)
[...]
> static void mtk_iommu_tlb_flush_page_nosync(struct iommu_iotlb_gather *gather, > unsigned long iova, size_t granule, > void *cookie) > { > + struct mtk_iommu_data *data = cookie; > + unsigned long flags; > + > + spin_lock_irqsave(&data->tlb_lock, flags); > mtk_iommu_tlb_add_flush_nosync(iova, granule, granule, true, cookie); > + spin_unlock_irqrestore(&data->tlb_lock, flags);
Given that you release the lock here, what prevents another nosync() operation being issued before you've managed to do the sync()?
Will
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