3.16.55-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Huacai Chen chenhc@lemote.com
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 84bda12af31f93 ("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 --- include/scsi/libsas.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/include/scsi/libsas.h +++ b/include/scsi/libsas.h @@ -170,11 +170,11 @@ 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) */
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]; };