swiotlb: print a warning when the swiotlb is full

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

Changes in v7:
- use dev_warn instead of pr_warn.

drivers/xen/swiotlb-xen.c

@@ -542,6 +542,7 @@ xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl,
 								 sg->length,
 								 dir);
 			if (map == SWIOTLB_MAP_ERROR) {
+				dev_warn(hwdev, "swiotlb buffer is full\n");
 				/* Don't panic here, we expect map_sg users
 				   to do proper error handling. */
 				xen_swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir,

lib/swiotlb.c

@@ -502,6 +502,7 @@ phys_addr_t swiotlb_tbl_map_single(struct device *hwdev,
 
 not_found:
 	spin_unlock_irqrestore(&io_tlb_lock, flags);
+	dev_warn(hwdev, "swiotlb buffer is full\n");
 	return SWIOTLB_MAP_ERROR;
 found:
 	spin_unlock_irqrestore(&io_tlb_lock, flags);