[PATCH for-next v2 07/18] RDMA/rxe: Add routine to compute the number of frags

Bob Pearson
2022-10-31T20:28:40Z

Add a subroutine named rxe_num_mr_frags() to compute the
number of skb frags needed to hold length bytes in an skb
when sending data from an mr starting at iova.

Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
---
drivers/infiniband/sw/rxe/rxe_loc.h | 1 +
drivers/infiniband/sw/rxe/rxe_mr.c | 68 +++++++++++++++++++++++++++++
2 files changed, 69 insertions(+)

diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h
index 81a611778d44..87fb052c1d0a 100644
--- a/drivers/infiniband/sw/rxe/rxe_loc.h
+++ b/drivers/infiniband/sw/rxe/rxe_loc.h
@@ -70,6 +70,7 @@ int rxe_mr_init_user(struct rxe_dev *rxe, u64 start, u64 length, u64 iova,
int rxe_mr_init_fast(int max_pages, struct rxe_mr *mr);
int rxe_add_frag(struct sk_buff *skb, struct rxe_phys_buf *buf,
int length, int offset);
+int rxe_num_mr_frags(struct rxe_mr *mr, u64 iova, int length);
int rxe_mr_copy(struct rxe_mr *mr, u64 iova, void *addr, int length,
enum rxe_mr_copy_op op);
int copy_data(struct rxe_pd *pd, int access, struct rxe_dma_info *dma,
diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c
index 2dcf37f32330..23abcf2a0198 100644
--- a/drivers/infiniband/sw/rxe/rxe_mr.c
+++ b/drivers/infiniband/sw/rxe/rxe_mr.c
@@ -320,6 +320,74 @@ int rxe_add_frag(struct sk_buff *skb, struct rxe_phys_buf *buf,
return 0;
}

+/**
+ * rxe_num_mr_frags() - Compute the number of skb frags needed to copy
+ * length bytes from an mr to an skb frag list.
+ * @mr: mr to copy data from
+ * @iova: iova in memory region as starting point
+ * @length: number of bytes to transfer
+ *
+ * Returns: the number of frags needed or a negative error
+ */
+int rxe_num_mr_frags(struct rxe_mr *mr, u64 iova, int length)
+{
+ struct rxe_phys_buf *buf;
+ struct rxe_map **map;
+ size_t buf_offset;
+ int bytes;
+ int m;
+ int i;
+ int num_frags = 0;
+ int err;
+
+ if (length == 0)
+ return 0;
+
+ if (mr->type == IB_MR_TYPE_DMA) {
+ while (length > 0) {
+ buf_offset = iova & ~PAGE_MASK;
+ bytes = PAGE_SIZE - buf_offset;
+ if (bytes > length)
+ bytes = length;
+ length -= bytes;
+ num_frags++;
+ }
+
+ return num_frags;
+ }
+
+ WARN_ON_ONCE(!mr->map);
+
+ err = mr_check_range(mr, iova, length);
+ if (err)
+ return err;
+
+ lookup_iova(mr, iova, &m, &i, &buf_offset);
+
+ map = mr->map + m;
+ buf = map[0]->buf + i;
+
+ while (length > 0) {
+ bytes = buf->size - buf_offset;
+ if (bytes > length)
+ bytes = length;
+ length -= bytes;
+ buf_offset = 0;
+ buf++;
+ i++;
+ num_frags++;
+
+ /* we won't overrun since we checked range above */
+ if (i == RXE_BUF_PER_MAP) {
+ i = 0;
+ map++;
+ buf = map[0]->buf;
+ }
+ }
+
+ return num_frags;
+}
+
/* copy data from a range (vaddr, vaddr+length-1) to or from
* a mr object starting at iova.
*/
--
2.34.1