sata_sx4: correctly handling failed allocation

Since kzalloc can be failed in memory pressure, return error when failed.

Signed-off-by: Insu Yun <wuninsu@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
diff --git a/drivers/ata/sata_sx4.c b/drivers/ata/sata_sx4.c
index fab504f..48301cb 100644
--- a/drivers/ata/sata_sx4.c
+++ b/drivers/ata/sata_sx4.c
@@ -1396,6 +1396,8 @@
 		addr = 0;
 		length = size * 1024 * 1024;
 		buf = kzalloc(ECC_ERASE_BUF_SZ, GFP_KERNEL);
+		if (!buf)
+			return 1;
 		while (addr < length) {
 			pdc20621_put_to_dimm(host, buf, addr,
 					     ECC_ERASE_BUF_SZ);