On 4/18/2019 7:13, Ferruh Yigit worte:
> On 4/18/2019 6:19 PM, Herakliusz Lipiec wrote:
> > A sucessfull call to rte_mp_request_sync does not guarantee that there
> > are valid messages in the buffer, and this should be checked for
> > before accessing data in the message.
> >
> > Fixes: c9aa56edec8e ("net/tap: access primary process queues from
> > secondary")
> > Cc: rasl...@mellanox.com
> > Cc: sta...@dpdk.org
> > Signed-off-by: Herakliusz Lipiec <herakliusz.lip...@intel.com>
> > ---
> > drivers/net/tap/rte_eth_tap.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/tap/rte_eth_tap.c
> > b/drivers/net/tap/rte_eth_tap.c index e9fda8cf6..a619a8850 100644
> > --- a/drivers/net/tap/rte_eth_tap.c
> > +++ b/drivers/net/tap/rte_eth_tap.c
> > @@ -2101,7 +2101,7 @@ tap_mp_attach_queues(const char *port_name,
> struct rte_eth_dev *dev)
> > request.len_param = sizeof(*request_param);
> > /* Send request and receive reply */
> > ret = rte_mp_request_sync(&request, &replies, &timeout);
> > - if (ret < 0) {
> > + if (ret < 0 || replies.n_receieved != 1) {
>
> The API documentation says:
>
> || * @return
>
>
>
> || * - On success, return 0.
>
>
>
> || * - On failure, return -1, and the reason will be stored in rte_errno.
>
> So if the API returns 0, why the reply is not valid, also if reply is not
> valid how
> can you rely on a value in 'replies'
>
> What do you think updating the 'rte_mp_request_sync()' API to return error
> whenever the reply is not valid?
The reply is not valid, because there is no valid msg pointer in replies.msg
(should be null)
replies.nb_received should be either 0 (if replies carries no message) or 1 (if
there is a message).
There are two other code paths that can return a success, but have no (valid)
message.
In rte_mp_request_sync there is a call to mp_request_sync which may return 0
with no message in case of:
- failure to send the message on behalf of remote
- the caller not caring about reply message.
I propose to add a check for nb_received to net/tap since this seems to be done
in everywhere
else when rte_mp_request_sync is called (this will do no harm), and also I
think that return codes should be fixed,
but that can be done irrelevant of this.
