Hi, Le mardi 11 novembre 2014 à 18:36 +0200, Haggai Eran a écrit : > 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@xxxxxxxxxxxx> > --- > 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) I would prefer the arguments in the same order as ib_copy_from_udata() int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t umem_offset, 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); As the function return a "int", no more than INT_MAX bytes (likely 2^31 - 1) can be copied. Perhaps changing the return type to to ssize_t would be better (and a check to enfore ssize_t maximum value). Or change the function could return 0 in case of success or a error code, just like ib_copy_from_udata(). > 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 */ > -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html