Commit 326ebe77 authored by Huacai Chen's avatar Huacai Chen Committed by Greg Kroah-Hartman

scsi: use dma_get_cache_alignment() as minimum DMA alignment

commit 90addc6b upstream.

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.
Signed-off-by: default avatarHuacai Chen <>
[hch: rebased and updated the comment and changelog]
Signed-off-by: default avatarChristoph Hellwig <>
Signed-off-by: default avatarMartin K. Petersen <>
Signed-off-by: default avatarGreg Kroah-Hartman <>
parent 4cb4d78c
......@@ -2041,11 +2041,13 @@ static 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);
struct request_queue *__scsi_alloc_queue(struct Scsi_Host *shost,
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