[PATCH v2] RDMA/umem: minor bug fix and cleanup in error handling paths

john.hubbard
2019-03-02T20:24:35Z

From: John Hubbard <jhubbard@nvidia.com>

1. Bug fix: the error handling release pages starting
at the first page that experienced an error.

2. Refinement: release_pages() is better than put_page()
in a loop.

3. Dead code removal: the check for (user_virt & ~page_mask)
is checking for a condition that can never happen,
because earlier:

user_virt = user_virt & page_mask;

...so, remove that entire phrase.

4. Minor: As long as I'm here, shorten up a couple of long lines
in the same function, without harming the ability to
grep for the printed error message.

Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Doug Ledford <dledford@redhat.com>
Cc: linux-rdma@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---

v2: Fixes a kbuild test robot reported build failure, by directly
including pagemap.h

drivers/infiniband/core/umem_odp.c | 25 ++++++++++---------------
1 file changed, 10 insertions(+), 15 deletions(-)

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index acb882f279cb..83872c1f3f2c 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -40,6 +40,7 @@
#include <linux/vmalloc.h>
#include <linux/hugetlb.h>
#include <linux/interval_tree_generic.h>
+#include <linux/pagemap.h>

#include <rdma/ib_verbs.h>
#include <rdma/ib_umem.h>
@@ -648,25 +649,17 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt,

if (npages < 0) {
if (npages != -EAGAIN)
- pr_warn("fail to get %zu user pages with error %d\n", gup_num_pages, npages);
+ pr_warn("fail to get %zu user pages with error %d\n",
+ gup_num_pages, npages);
else
- pr_debug("fail to get %zu user pages with error %d\n", gup_num_pages, npages);
+ pr_debug("fail to get %zu user pages with error %d\n",
+ gup_num_pages, npages);
break;
}

bcnt -= min_t(size_t, npages << PAGE_SHIFT, bcnt);
mutex_lock(&umem_odp->umem_mutex);
for (j = 0; j < npages; j++, user_virt += PAGE_SIZE) {
- if (user_virt & ~page_mask) {
- p += PAGE_SIZE;
- if (page_to_phys(local_page_list[j]) != p) {
- ret = -EFAULT;
- break;
- }
- put_page(local_page_list[j]);
- continue;
- }
-
ret = ib_umem_odp_map_dma_single_page(
umem_odp, k, local_page_list[j],
access_mask, current_seq);
@@ -684,9 +677,11 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt,
mutex_unlock(&umem_odp->umem_mutex);

if (ret < 0) {
- /* Release left over pages when handling errors. */
- for (++j; j < npages; ++j)
- put_page(local_page_list[j]);
+ /*
+ * Release pages, starting at the the first page
+ * that experienced an error.
+ */
+ release_pages(&local_page_list[j], npages - j);
break;
}
}
--
2.21.0