[PATCH] quiet down swiotlb warnings

[Rik van Riel]

It turns out that the qla2xxx driver sometimes fills up the iotlb
on purpose and throttles itself when pci_map_sg() fails.  In the
case of a driver that expects and handles pci_map_sg() failures,
we should not spam the user's console with swiotlb full messages.

If the user runs a driver that cannot handle the swiotlb filling
up, 5 warnings should be enough to leave a clue.

Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
--- linux-2.6.21.noarch/lib/swiotlb.c.quiet	2007-06-01 13:23:04.000000000 -0400
+++ linux-2.6.21.noarch/lib/swiotlb.c	2007-06-01 13:25:49.000000000 -0400
@@ -505,6 +505,7 @@ swiotlb_free_coherent(struct device *hwd
 static void
 swiotlb_full(struct device *dev, size_t size, int dir, int do_panic)
 {
+	static int warnings = 0;
 	/*
 	 * Ran out of IOMMU space for this operation. This is very bad.
 	 * Unfortunately the drivers cannot handle this operation properly.
@@ -512,8 +513,9 @@ swiotlb_full(struct device *dev, size_t 
 	 * When the mapping is small enough return a static buffer to limit
 	 * the damage, or panic when the transfer is too big.
 	 */
-	printk(KERN_ERR "DMA: Out of SW-IOMMU space for %zu bytes at "
-	       "device %s\n", size, dev ? dev->bus_id : "?");
+	if (++warnings < 5)
+		printk(KERN_ERR "DMA: Out of SW-IOMMU space for %zu bytes at "
+		       "device %s\n", size, dev ? dev->bus_id : "?");
 
 	if (size > io_tlb_overflow && do_panic) {
 		if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL)