path: root/drivers/scsi/scsi_lib.c
diff options
authorHuacai Chen <chenhc@lemote.com>2017-11-21 14:23:38 +0100
committerMartin K. Petersen <martin.petersen@oracle.com>2017-11-21 23:05:57 -0500
commit90addc6b3c9cda0146fbd62a08e234c2b224a80c (patch)
tree7cdc0b3f4b87d26c8f91125edaea8723764526bf /drivers/scsi/scsi_lib.c
parent860dd4424f344400b491b212ee4acb3a358ba9d9 (diff)
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>
Diffstat (limited to 'drivers/scsi/scsi_lib.c')
1 files changed, 6 insertions, 4 deletions
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 1cbc497e00bd..00742c50cd44 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -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);

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