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Commit c5d76f13 authored by Haggai Eran's avatar Haggai Eran Committed by Roland Dreier
Browse files

IB/core: Add umem function to read data from user-space 



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: default avatarHaggai Eran <haggaie@mellanox.com>
Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
parent 406f9e5f

drivers/infiniband/core/umem.c

+34 −0
Original line number Diff line number Diff line
@@ -292,3 +292,37 @@ 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 0 on success, or an error code.

 */

int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t offset,

		      size_t length)

{

	size_t end = offset + length;

	int ret;



	if (offset > umem->length || length > umem->length - offset) {

		pr_err("ib_umem_copy_from not in range. offset: %zd umem length: %zd end: %zd\n",

		       offset, umem->length, end);

		return -EINVAL;

	}



	ret = sg_pcopy_to_buffer(umem->sg_head.sgl, umem->nmap, dst, length,

				 offset + ib_umem_offset(umem));



	if (ret < 0)

		return ret;

	else if (ret != length)

		return -EINVAL;

	else

		return 0;

}

EXPORT_SYMBOL(ib_umem_copy_from);

include/rdma/ib_umem.h

+2 −0
Original line number Diff line number Diff line
@@ -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(void *dst, struct ib_umem *umem, size_t offset,

		      size_t length);



#else /* CONFIG_INFINIBAND_USER_MEM */