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

commit c2e8fbf908afd81ad502b567a6639598f92c9b9d upstream.

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 84bda12af3 ("libata:
align ap->sector_buf") and Commit 4ee34ea3a12396f35b26 ("libata: Align
ata_device's id on a cacheline").

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>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
This commit is contained in:
Huacai Chen 2017-11-21 14:23:39 +01:00 committed by syphyr
parent 375d1ebdce
commit ad40571b7a
1 changed files with 1 additions and 1 deletions
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include/scsi/libsas.h
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@ -170,12 +170,12 @@ enum ata_command_set {
struct sata_device {
enum ata_command_set command_set;
struct smp_resp rps_resp; /* report_phy_sata_resp */
u8 port_no; /* port number, if this is a PM (Port) */
int pm_result;
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];
};