Commit c2e8fbf9 authored Nov 21, 2017 by Huacai Chen Committed by Martin K. Petersen Nov 21, 2017

scsi: libsas: align sata_device's rps_resp on a cacheline



The rps_resp buffer in ata_device is a DMA target, but it isn't
explicitly cacheline aligned. Due to this, adjacent fields can be
overwritten with stale data from memory on non-coherent architectures.
As a result, the kernel is sometimes unable to communicate with an SATA
device behind a SAS expander.

Fix this by ensuring that the rps_resp buffer is cacheline aligned.

This issue is similar to that fixed by Commit 84bda12a ("libata:
align ap->sector_buf") and Commit 4ee34ea3 ("libata: Align
ata_device's id on a cacheline").

Cc: stable@vger.kernel.org
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

parent 90addc6b

include/scsi/libsas.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -159,11 +159,11 @@ struct expander_device {

		struct sata_device {
		unsigned int class;
		struct smp_resp rps_resp; /* report_phy_sata_resp */
		u8 port_no; /* port number, if this is a PM (Port) */

		struct ata_port *ap;
		struct ata_host ata_host;
		struct smp_resp rps_resp ____cacheline_aligned; /* report_phy_sata_resp */
		u8 fis[ATA_RESP_FIS_SIZE];
		};

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