drivers/dma/ioat/dma.c: check DMA mapping error in ioat_dma_self_test()

Check DMA mapping return values in function ioat_dma_self_test() to get
rid of following warning message.

------------[ cut here ]------------
WARNING: CPU: 0 PID: 1203 at lib/dma-debug.c:937 check_unmap+0x4c0/0x9a0()
ioatdma 0000:00:04.0: DMA-API: device driver failed to check map error[device address=0x000000085191b000] [size=2000 bytes] [mapped as single]
Modules linked in: ioatdma(+) mac_hid wmi acpi_pad lp parport hidd_generic usbhid hid ixgbe isci dca libsas ahci ptp libahci scsi_transport_sas meegaraid_sas pps_core mdio
CPU: 0 PID: 1203 Comm: systemd-udevd Not tainted 3.13.0-rc4+ #8
Hardware name: Intel Corporation BRICKLAND/BRICKLAND, BIOS BRIVTIIN1.86B.0044.L09.1311181644 11/18/2013
Call Trace:
dump_stack+0x4d/0x66
warn_slowpath_common+0x7d/0xa0
warn_slowpath_fmt+0x4c/0x50
check_unmap+0x4c0/0x9a0
debug_dma_unmap_page+0x81/0x90
ioat_dma_self_test+0x3d2/0x680 [ioatdma]
ioat3_dma_self_test+0x12/0x30 [ioatdma]
ioat_probe+0xf4/0x110 [ioatdma]
ioat3_dma_probe+0x268/0x410 [ioatdma]
ioat_pci_probe+0x122/0x1b0 [ioatdma]
local_pci_probe+0x45/0xa0
pci_device_probe+0xd9/0x130
driver_probe_device+0x171/0x490
__driver_attach+0x93/0xa0
bus_for_each_dev+0x6b/0xb0
driver_attach+0x1e/0x20
bus_add_driver+0x1f8/0x2b0
driver_register+0x81/0x110
__pci_register_driver+0x60/0x70
ioat_init_module+0x89/0x1000 [ioatdma]
do_one_initcall+0xe2/0x250
load_module+0x2313/0x2a00
SyS_init_module+0xd9/0x130
system_call_fastpath+0x1a/0x1f
---[ end trace 990c591681d27c31 ]---
Mapped at:
debug_dma_map_page+0xbe/0x180
ioat_dma_self_test+0x1ab/0x680 [ioatdma]
ioat3_dma_self_test+0x12/0x30 [ioatdma]
ioat_probe+0xf4/0x110 [ioatdma]
ioat3_dma_probe+0x268/0x410 [ioatdma]

Signed-off-by: Jiang Liu <[e-mail]>
Cc: Vinod Koul <[e-mail]>
Cc: Dan Williams <[e-mail]>
Cc: Bartlomiej Zolnierkiewicz <[e-mail]>
Cc: Kyungmin Park <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/dma/ioat/dma.c

···
 	}
 
 	dma_src = dma_map_single(dev, src, IOAT_TEST_SIZE, DMA_TO_DEVICE);
+	if (dma_mapping_error(dev, dma_src)) {
+		dev_err(dev, "mapping src buffer failed\n");
+		goto free_resources;
+	}
 	dma_dest = dma_map_single(dev, dest, IOAT_TEST_SIZE, DMA_FROM_DEVICE);
+	if (dma_mapping_error(dev, dma_dest)) {
+		dev_err(dev, "mapping dest buffer failed\n");
+		goto unmap_src;
+	}
 	flags = DMA_PREP_INTERRUPT;
 	tx = device->common.device_prep_dma_memcpy(dma_chan, dma_dest, dma_src,
 						   IOAT_TEST_SIZE, flags);
···
 	}
 
 unmap_dma:
-	dma_unmap_single(dev, dma_src, IOAT_TEST_SIZE, DMA_TO_DEVICE);
 	dma_unmap_single(dev, dma_dest, IOAT_TEST_SIZE, DMA_FROM_DEVICE);
+unmap_src:
+	dma_unmap_single(dev, dma_src, IOAT_TEST_SIZE, DMA_TO_DEVICE);
 free_resources:
 	dma->device_free_chan_resources(dma_chan);
 out: