IB/mthca: Clear ICM pages before handing to FW

commit 87afd448b186c885d67a08b7417cd46253b6a9d6 upstream

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

[ 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: Eli Cohen <eli@mellanox.co.il>
Signed-off-by: Roland Dreier <rolandd@cisco.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/infiniband/hw/mthca/mthca_memfree.c b/drivers/infiniband/hw/mthca/mthca_memfree.c
index 252db0822f6cbc2e8d1f092b6c9965aa102142ef..0b92d3ef951129f1384daa0feb7f52a6db580db2 100644 (file)
--- 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;