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scsi: use dma_get_cache_alignment() as minimum DMA alignment

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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>
This commit is contained in:
Huacai Chen 2017-11-21 14:23:38 +01:00 committed by Martin K. Petersen
parent 860dd4424f
commit 90addc6b3c
1 changed files with 6 additions and 4 deletions
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10
drivers/scsi/scsi_lib.c
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@ -2148,11 +2148,13 @@ void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
q->limits.cluster = 0;
/*
* set a reasonable default alignment on word boundaries: the
* host and device may alter it using
* blk_queue_update_dma_alignment() later.
* Set a reasonable default alignment: The larger of 32-byte (dword),
* which is a common minimum for HBAs, and the minimum DMA alignment,
* which is set by the platform.
*
* Devices that require a bigger alignment can increase it later.
*/
blk_queue_dma_alignment(q, 0x03);
blk_queue_dma_alignment(q, max(4, dma_get_cache_alignment()) - 1);
}
EXPORT_SYMBOL_GPL(__scsi_init_queue);