IB/mthca: Clear ICM pages before handing to FW

Current memfree FW has a bug which in some cases, assumes that ICM
pages passed to it are cleared.  This patch uses __GFP_ZERO to
allocate all ICM pages passed to the FW.  Once firmware with a fix is
released, we can make the workaround conditional on firmware version.

This fixes the bug reported by Arthur Kepner <akepner@sgi.com> here:
http://lists.openfabrics.org/pipermail/general/2008-May/050026.html

Cc: <stable@kernel.org>
Signed-off-by: Eli Cohen <eli@mellanox.co.il>

[ Rewritten to be a one-liner using __GFP_ZERO instead of vmap()ing
  ICM memory and memset()ing it to 0. - Roland ]

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

1 files changed, 5 insertions, 1 deletions

diff --git a/drivers/infiniband/hw/mthca/mthca_memfree.c b/drivers/infiniband/hw/mthca/mthca_memfree.c
index b224079d4e1f..d5862e5d99a0 100644
--- a/drivers/infiniband/hw/mthca/mthca_memfree.c
+++ b/drivers/infiniband/hw/mthca/mthca_memfree.c
@@ -109,7 +109,11 @@ static int mthca_alloc_icm_pages(struct scatterlist *mem, int order, gfp_t gfp_m
 {
         struct page *page;
 
-        page = alloc_pages(gfp_mask, order);
+        /*
+         * Use __GFP_ZERO because buggy firmware assumes ICM pages are
+         * cleared, and subtle failures are seen if they aren't.
+         */
+        page = alloc_pages(gfp_mask | __GFP_ZERO, order);
         if (!page)
                 return -ENOMEM;