IB/mlx4: Consolidate code to get an entry from a struct mlx4_buf

We use struct mlx4_buf for kernel QP, CQ and SRQ buffers, and the code
to look up an entry is duplicated in get_cqe_from_buf() and the QP and
SRQ versions of get_wqe().  Factor this out into mlx4_buf_offset().

This will also make it easier to switch over to using vmap() for buffers.

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

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/mlx4/device.h b/include/linux/mlx4/device.h
index 222815d..a0afa75 100644
--- a/include/linux/mlx4/device.h
+++ b/include/linux/mlx4/device.h
@@ -308,6 +308,14 @@ struct mlx4_init_port_param {
 int mlx4_buf_alloc(struct mlx4_dev *dev, int size, int max_direct,
 		   struct mlx4_buf *buf);
 void mlx4_buf_free(struct mlx4_dev *dev, int size, struct mlx4_buf *buf);
+static inline void *mlx4_buf_offset(struct mlx4_buf *buf, int offset)
+{
+	if (buf->nbufs == 1)
+		return buf->u.direct.buf + offset;
+	else
+		return buf->u.page_list[offset >> PAGE_SHIFT].buf +
+			(offset & (PAGE_SIZE - 1));
+}
 
 int mlx4_pd_alloc(struct mlx4_dev *dev, u32 *pdn);
 void mlx4_pd_free(struct mlx4_dev *dev, u32 pdn);