[3.16.y-ckt stable] Patch "libata: Align ata_device's id on a cacheline" has been added to the 3.16.y-ckt tree

[3.16.y-ckt stable] Patch "libata: Align ata_device's id on a cacheline" has been added to the 3.16.y-ckt tree

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    libata: Align ata_device's id on a cacheline

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt26.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

---8<------------------------------------------------------------

>From 12e2777fa63b28da14bbbf646039d81b6023822b Mon Sep 17 00:00:00 2001
From: Harvey Hunt <harvey.hunt@imgtec.com>
Date: Wed, 24 Feb 2016 15:16:43 +0000
Subject: libata: Align ata_device's id on a cacheline

commit 4ee34ea3a12396f35b26d90a094c75db95080baa upstream.

The id 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 ATA device.

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

This issue is similar to that fixed by Commit 84bda12af31f
("libata: align ap->sector_buf").

Signed-off-by: Harvey Hunt <harvey.hunt@imgtec.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 include/linux/libata.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/libata.h b/include/linux/libata.h
index 714274450c07..bd83b8e83cfe 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -714,7 +714,7 @@ struct ata_device {
 	union {
 		u16		id[ATA_ID_WORDS]; /* IDENTIFY xxx DEVICE data */
 		u32		gscr[SATA_PMP_GSCR_DWORDS]; /* PMP GSCR block */
-	};
+	} ____cacheline_aligned;

 	/* DEVSLP Timing Variables from Identify Device Data Log */
 	u8			devslp_timing[ATA_LOG_DEVSLP_SIZE];