[PATCH v2 04/17] IB/core: Add umem function to read data from user-space

Haggai Eran
2014-11-11T16:36:10Z

In some drivers there's a need to read data from a user space area that
was pinned using ib_umem, when running from a different process context.

The ib_umem_copy_from function allows reading data from the physical pages
pinned in the ib_umem struct.

Signed-off-by: Haggai Eran <haggaie-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
---
drivers/infiniband/core/umem.c | 26 ++++++++++++++++++++++++++
include/rdma/ib_umem.h | 2 ++
2 files changed, 28 insertions(+)

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index e0f883292374..77bec75963e7 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -292,3 +292,29 @@ int ib_umem_page_count(struct ib_umem *umem)
return n;
}
EXPORT_SYMBOL(ib_umem_page_count);
+
+/*
+ * Copy from the given ib_umem's pages to the given buffer.
+ *
+ * umem - the umem to copy from
+ * offset - offset to start copying from
+ * dst - destination buffer
+ * length - buffer length
+ *
+ * Returns the number of copied bytes, or an error code.
+ */
+int ib_umem_copy_from(struct ib_umem *umem, size_t offset, void *dst,
+ size_t length)
+{
+ size_t end = offset + length;
+
+ if (offset > umem->length || end > umem->length || end < offset) {
+ pr_err("ib_umem_copy_from not in range. offset: %zd umem length: %zd end: %zd\n",
+ offset, umem->length, end);
+ return -EINVAL;
+ }
+
+ return sg_pcopy_to_buffer(umem->sg_head.sgl, umem->nmap, dst, length,
+ offset + ib_umem_offset(umem));
+}
+EXPORT_SYMBOL(ib_umem_copy_from);
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index 7ed6d4ff58dc..ee897724cbf8 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -84,6 +84,8 @@ struct ib_umem *ib_umem_get(struct ib_ucontext *context, unsigned long addr,
size_t size, int access, int dmasync);
void ib_umem_release(struct ib_umem *umem);
int ib_umem_page_count(struct ib_umem *umem);
+int ib_umem_copy_from(struct ib_umem *umem, size_t start, void *dst,
+ size_t length);

#else /* CONFIG_INFINIBAND_USER_MEM */