2019-05-29 15:14:33

by Gustavo A. R. Silva

Subject: [PATCH][next] IB/rdmavt: Use struct_size() helper

Make use of the struct_size() helper instead of an open-coded version
in order to avoid any potential type mistakes, in particular in the
context in which this code is being used.

So, replace the following form:

sizeof(struct rvt_sge) * init_attr->cap.max_send_sge + sizeof(struct rvt_swqe)

with:

struct_size(swq, sg_list, init_attr->cap.max_send_sge)

and so on...

Also, notice that variable size is unnecessary, hence it is removed.

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
drivers/infiniband/sw/rdmavt/qp.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/infiniband/sw/rdmavt/qp.c b/drivers/infiniband/sw/rdmavt/qp.c
index 31a2e65e4906..a60f5faea198 100644
--- a/drivers/infiniband/sw/rdmavt/qp.c
+++ b/drivers/infiniband/sw/rdmavt/qp.c
@@ -988,9 +988,7 @@ struct ib_qp *rvt_create_qp(struct ib_pd *ibpd,
case IB_QPT_UC:
case IB_QPT_RC:
case IB_QPT_UD:
- sz = sizeof(struct rvt_sge) *
- init_attr->cap.max_send_sge +
- sizeof(struct rvt_swqe);
+ sz = struct_size(swq, sg_list, init_attr->cap.max_send_sge);
swq = vzalloc_node(array_size(sz, sqsize), rdi->dparms.node);
if (!swq)
return ERR_PTR(-ENOMEM);
--
2.21.0

2019-05-30 18:27:50

by Dennis Dalessandro

Subject: Re: [PATCH][next] IB/rdmavt: Use struct_size() helper

On 5/29/2019 11:12 AM, Gustavo A. R. Silva wrote:
> Make use of the struct_size() helper instead of an open-coded version
> in order to avoid any potential type mistakes, in particular in the
> context in which this code is being used.
>
> So, replace the following form:
>
> sizeof(struct rvt_sge) * init_attr->cap.max_send_sge + sizeof(struct rvt_swqe)
>
> with:
>
> struct_size(swq, sg_list, init_attr->cap.max_send_sge)
>
> and so on...
>
> Also, notice that variable size is unnecessary, hence it is removed.
>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
> ---
> drivers/infiniband/sw/rdmavt/qp.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/infiniband/sw/rdmavt/qp.c b/drivers/infiniband/sw/rdmavt/qp.c
> index 31a2e65e4906..a60f5faea198 100644
> --- a/drivers/infiniband/sw/rdmavt/qp.c
> +++ b/drivers/infiniband/sw/rdmavt/qp.c
> @@ -988,9 +988,7 @@ struct ib_qp *rvt_create_qp(struct ib_pd *ibpd,
> case IB_QPT_UC:
> case IB_QPT_RC:
> case IB_QPT_UD:
> - sz = sizeof(struct rvt_sge) *
> - init_attr->cap.max_send_sge +
> - sizeof(struct rvt_swqe);
> + sz = struct_size(swq, sg_list, init_attr->cap.max_send_sge);
> swq = vzalloc_node(array_size(sz, sqsize), rdi->dparms.node);
> if (!swq)
> return ERR_PTR(-ENOMEM);
>

Looks correct, I don't think this makes the code easier to read though.
The macro name "struct_size" is misleading to me. Maybe that's just me,
and in any case...

Reviewed-by: Dennis Dalessandro <[email protected]>

2019-05-30 18:30:34

by Jason Gunthorpe

Subject: Re: [PATCH][next] IB/rdmavt: Use struct_size() helper

On Thu, May 30, 2019 at 02:26:22PM -0400, Dennis Dalessandro wrote:
> On 5/29/2019 11:12 AM, Gustavo A. R. Silva wrote:
> > Make use of the struct_size() helper instead of an open-coded version
> > in order to avoid any potential type mistakes, in particular in the
> > context in which this code is being used.
> >
> > So, replace the following form:
> >
> > sizeof(struct rvt_sge) * init_attr->cap.max_send_sge + sizeof(struct rvt_swqe)
> >
> > with:
> >
> > struct_size(swq, sg_list, init_attr->cap.max_send_sge)
> >
> > and so on...
> >
> > Also, notice that variable size is unnecessary, hence it is removed.
> >
> > This code was detected with the help of Coccinelle.
> >
> > Signed-off-by: Gustavo A. R. Silva <[email protected]>
> > drivers/infiniband/sw/rdmavt/qp.c | 4 +---
> > 1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/drivers/infiniband/sw/rdmavt/qp.c b/drivers/infiniband/sw/rdmavt/qp.c
> > index 31a2e65e4906..a60f5faea198 100644
> > +++ b/drivers/infiniband/sw/rdmavt/qp.c
> > @@ -988,9 +988,7 @@ struct ib_qp *rvt_create_qp(struct ib_pd *ibpd,
> > case IB_QPT_UC:
> > case IB_QPT_RC:
> > case IB_QPT_UD:
> > - sz = sizeof(struct rvt_sge) *
> > - init_attr->cap.max_send_sge +
> > - sizeof(struct rvt_swqe);
> > + sz = struct_size(swq, sg_list, init_attr->cap.max_send_sge);
> > swq = vzalloc_node(array_size(sz, sqsize), rdi->dparms.node);
> > if (!swq)
> > return ERR_PTR(-ENOMEM);
> >
>
> Looks correct, I don't think this makes the code easier to read though. The
> macro name "struct_size" is misleading to me. Maybe that's just me, and in
> any case...

It is struct_size because it computes the full size of a struct ending in a
variable length array with N items.

The previous code was wonky because it assumes that struct rvt_swqe is
the underlying type of sg_list, while the new version gets the type
information automatically.

Jason

2019-05-30 18:45:29

by Jason Gunthorpe

Subject: Re: [PATCH][next] IB/rdmavt: Use struct_size() helper

On Wed, May 29, 2019 at 10:12:48AM -0500, Gustavo A. R. Silva wrote:
> Make use of the struct_size() helper instead of an open-coded version
> in order to avoid any potential type mistakes, in particular in the
> context in which this code is being used.
>
> So, replace the following form:
>
> sizeof(struct rvt_sge) * init_attr->cap.max_send_sge + sizeof(struct rvt_swqe)
>
> with:
>
> struct_size(swq, sg_list, init_attr->cap.max_send_sge)
>
> and so on...
>
> Also, notice that variable size is unnecessary, hence it is removed.
>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
> Reviewed-by: Dennis Dalessandro <[email protected]>
> ---
> drivers/infiniband/sw/rdmavt/qp.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)

Applied to for-next, thanks

Jason