libata: Align ata_device's id on a cacheline

HarveyHunt · htejun · commit 4ee34ea3a123 · 2016-02-25T16:37:06.000-05:00
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 84bda12 ("libata: align ap->sector_buf"). Signed-off-by: Harvey Hunt <harvey.hunt@imgtec.com> Cc: linux-kernel@vger.kernel.org Cc: <stable@vger.kernel.org> # 2.6.18 Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/include/linux/libata.h b/include/linux/libata.h
@@ -720,7 +720,7 @@ 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];
