[openib-general] Re: [PATCH updated] mthca: fix page shift calculation

[Roland Dreier]

    Michael> Hmm.  Lets suppose I have a first chunk in bytes 1 to
    Michael> 2095, and then another chunk in bytes 0x100000 to
    Michael> 0x1ffffff - should not we limit the page size to 4K? Does
    Michael> your proposed change do this?

Yes, you're right again.  It seems like we can get rid of some special
casing and just do things like this:

--- infiniband/hw/mthca/mthca_provider.c	(revision 4754)
+++ infiniband/hw/mthca/mthca_provider.c	(working copy)
@@ -771,24 +771,20 @@ static struct ib_mr *mthca_reg_phys_mr(s
 	if ((*iova_start & ~PAGE_MASK) != (buffer_list[0].addr & ~PAGE_MASK))
 		return ERR_PTR(-EINVAL);
 
-	if (num_phys_buf > 1 &&
-	    ((buffer_list[0].addr + buffer_list[0].size) & ~PAGE_MASK))
-		return ERR_PTR(-EINVAL);
-
 	mask = 0;
 	total_size = 0;
 	for (i = 0; i < num_phys_buf; ++i) {
-		if (i != 0 && buffer_list[i].addr & ~PAGE_MASK)
-			return ERR_PTR(-EINVAL);
-		if (i != 0 && i != num_phys_buf - 1 &&
-		    (buffer_list[i].size & ~PAGE_MASK))
-			return ERR_PTR(-EINVAL);
+		if (i != 0)
+			mask |= buffer_list[i].addr;
+		if (i != num_phys_buf - 1)
+			mask |= buffer_list[i].addr + buffer_list[i].size;
 
 		total_size += buffer_list[i].size;
-		if (i > 0)
-			mask |= buffer_list[i].addr;
 	}
 
+	if (mask & ~PAGE_MASK)
+		return ERR_PTR(-EINVAL);
+
 	/* Find largest page shift we can use to cover buffers */
 	for (shift = PAGE_SHIFT; shift < 31; ++shift)
 		if (num_phys_buf > 1) {