Patch "scsi: libsas: align sata_device's rps_resp on a cacheline" has been added to the 4.4-stable tree

Patch "scsi: libsas: align sata_device's rps_resp on a cacheline" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

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

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     scsi-libsas-align-sata_device-s-rps_resp-on-a-cacheline.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From c2e8fbf908afd81ad502b567a6639598f92c9b9d Mon Sep 17 00:00:00 2001
From: Huacai Chen <chenhc@lemote.com>
Date: Tue, 21 Nov 2017 14:23:39 +0100
Subject: scsi: libsas: align sata_device's rps_resp on a cacheline

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 include/scsi/libsas.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -165,11 +165,11 @@ 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];
 };
 


Patches currently in stable-queue which might be from chenhc@lemote.com are

queue-4.4/scsi-use-dma_get_cache_alignment-as-minimum-dma-alignment.patch
queue-4.4/scsi-libsas-align-sata_device-s-rps_resp-on-a-cacheline.patch