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scsi: use dma_get_cache_alignment() as minimum DMA alignment
In non-coherent DMA mode, kernel uses cache flushing operations to maintain I/O coherency, so scsi's block queue should be aligned to the value returned by dma_get_cache_alignment(). Otherwise, If a DMA buffer and a kernel structure share a same cache line, and if the kernel structure has dirty data, cache_invalidate (no writeback) will cause data corruption. Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen <chenhc@lemote.com> [hch: rebased and updated the comment and changelog] Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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1 changed files with 6 additions and 4 deletions
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@ -2148,11 +2148,13 @@ void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
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q->limits.cluster = 0;
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/*
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* set a reasonable default alignment on word boundaries: the
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* host and device may alter it using
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* blk_queue_update_dma_alignment() later.
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* Set a reasonable default alignment: The larger of 32-byte (dword),
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* which is a common minimum for HBAs, and the minimum DMA alignment,
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* which is set by the platform.
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*
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* Devices that require a bigger alignment can increase it later.
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*/
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blk_queue_dma_alignment(q, 0x03);
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blk_queue_dma_alignment(q, max(4, dma_get_cache_alignment()) - 1);
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}
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EXPORT_SYMBOL_GPL(__scsi_init_queue);
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