[SCSI] ipr: use memory_read_from_buffer()

Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NBrian King <brking@us.ibm.com>
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/ipr.c

@@ -2456,20 +2456,14 @@ static ssize_t ipr_read_trace(struct kobject *kobj,
 	struct Scsi_Host *shost = class_to_shost(dev);
 	struct ipr_ioa_cfg *ioa_cfg = (struct ipr_ioa_cfg *)shost->hostdata;
 	unsigned long lock_flags = 0;
-	int size = IPR_TRACE_SIZE;
-	char *src = (char *)ioa_cfg->trace;
-
-	if (off > size)
-		return 0;
-	if (off + count > size) {
-		size -= off;
-		count = size;
-	}
+	ssize_t ret;
 
 	spin_lock_irqsave(ioa_cfg->host->host_lock, lock_flags);
-	memcpy(buf, &src[off], count);
+	ret = memory_read_from_buffer(buf, count, &off, ioa_cfg->trace,
+				IPR_TRACE_SIZE);
 	spin_unlock_irqrestore(ioa_cfg->host->host_lock, lock_flags);
-	return count;
+
+	return ret;
 }
 
 static struct bin_attribute ipr_trace_attr = {