[PATCH V10 4/4] libsas: Align sata_device's rps_resp on a cacheline

From: Huacai Chen
Date: Thu Nov 16 2017 - 23:31:04 EST

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").

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx>
include/scsi/libsas.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index 0f9cbf9..6df6fe0 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -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 */