[IB] mthca: Fix doorbell record resource leak

If we allocate a bunch of doorbell records and then free them, we'll
end up with completely empty pages, which we then free.  However, when
we come back to allocate more doorbell pages, we have to reallocate
those empty pages rather than always trying to take a slot that we've
never used.  If we don't, we eventually use up every slot and fail to
allocate a doorbell record, even though we have plenty of free space.

Signed-off-by: Roland Dreier <rolandd@cisco.com>

diff --git a/drivers/infiniband/hw/mthca/mthca_memfree.c b/drivers/infiniband/hw/mthca/mthca_memfree.c
index 1827400f189be87a61c5c7c062147a978a16b133..d0c41fe046f077c835fcca5fe0bbab3f4ae6e86d 100644 (file)
--- a/drivers/infiniband/hw/mthca/mthca_memfree.c
+++ b/drivers/infiniband/hw/mthca/mthca_memfree.c
@@ -529,12 +529,25 @@ int mthca_alloc_db(struct mthca_dev *dev, int type, u32 qn, __be32 **db)
                        goto found;
                }
 
+       for (i = start; i != end; i += dir)
+               if (!dev->db_tab->page[i].db_rec) {
+                       page = dev->db_tab->page + i;
+                       goto alloc;
+               }
+
        if (dev->db_tab->max_group1 >= dev->db_tab->min_group2 - 1) {
                ret = -ENOMEM;
                goto out;
        }
 
+       if (group == 0)
+               ++dev->db_tab->max_group1;
+       else
+               --dev->db_tab->min_group2;
+
        page = dev->db_tab->page + end;
+
+alloc:
        page->db_rec = dma_alloc_coherent(&dev->pdev->dev, 4096,
                                          &page->mapping, GFP_KERNEL);
        if (!page->db_rec) {
@@ -554,10 +567,6 @@ int mthca_alloc_db(struct mthca_dev *dev, int type, u32 qn, __be32 **db)
        }
 
        bitmap_zero(page->used, MTHCA_DB_REC_PER_PAGE);
-       if (group == 0)
-               ++dev->db_tab->max_group1;
-       else
-               --dev->db_tab->min_group2;
 
 found:
        j = find_first_zero_bit(page->used, MTHCA_DB_REC_PER_PAGE);