Re: [PATCH 2/2] migration/rdma: set the REUSEADDR option for destination

[Jinpu Wang]

On Tue, Feb 1, 2022 at 7:39 PM Pankaj Gupta <pankaj.gupta@ionos.com> wrote:
>
> > This allow address could be reused to avoid rdma_bind_addr error
> > out.
>
> Seems we are proposing to allow multiple connections on same source ip
> port pair?
according to the man page, it's more about the destination side which
is the incoming side.[1]
We hit the error on the migration target when there are many migration
tests in parallel:
"RDMA ERROR: Error: could not rdma_bind_addr!"

[1]https://manpages.debian.org/testing/librdmacm-dev/rdma_set_option.3.en.html
> >
> > Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
> > ---
> >  migration/rdma.c | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/migration/rdma.c b/migration/rdma.c
> > index 2e223170d06d..b498ef013c77 100644
> > --- a/migration/rdma.c
> > +++ b/migration/rdma.c
> > @@ -2705,6 +2705,7 @@ static int qemu_rdma_dest_init(RDMAContext *rdma, 
> > Error **errp)
> >      char ip[40] = "unknown";
> >      struct rdma_addrinfo *res, *e;
> >      char port_str[16];
> > +    int reuse = 1;
> >
> >      for (idx = 0; idx < RDMA_WRID_MAX; idx++) {
> >          rdma->wr_data[idx].control_len = 0;
> > @@ -2740,6 +2741,12 @@ static int qemu_rdma_dest_init(RDMAContext *rdma, 
> > Error **errp)
> >          goto err_dest_init_bind_addr;
> >      }
> >
> > +    ret = rdma_set_option(listen_id, RDMA_OPTION_ID, 
> > RDMA_OPTION_ID_REUSEADDR,
> > +                         &reuse, sizeof reuse);
>
> maybe we can just write '1' directly on the argument list of 
> 'rdma_set_option'.
> Assuming reuseaddr does not effect core rdma transport? change seems ok to me.
I feel it's cleaner to do it with a variable than force conversion of
1 to void *.

It's bound to the cm_id which is newly created a few lines above, so
does not affect core rdma transport.

>
> Thanks,
> Pankaj
Thanks for the review!

Jinpu Wang
>
> > +    if (ret) {
> > +        ERROR(errp, "Error: could not set REUSEADDR option");
> > +        goto err_dest_init_bind_addr;
> > +    }
> >      for (e = res; e != NULL; e = e->ai_next) {
> >          inet_ntop(e->ai_family,
> >              &((struct sockaddr_in *) e->ai_dst_addr)->sin_addr, ip, sizeof 
> > ip);
> > --
> > 2.25.1
> >