Re: [PATCH] net/rds: fix WARNING in rds_conn_connect_if_down

[Edward Adam Davis <eadavis@qq.com>]

On Mon, 4 Mar 2024 17:07:07 +0000, Simon Horman wrote:
> > If connection isn't established yet, get_mr() will fail, trigger connection after
> > get_mr().
> > 
> > Fixes: 584a8279a44a ("RDS: RDMA: return appropriate error on rdma map failures") 
> > Reported-and-tested-by: syzbot+d4faee732755bba9838e@syzkaller.appspotmail.com
> > Signed-off-by: Edward Adam Davis <eadavis@qq.com>
> > ---
> >  net/rds/rdma.c | 3 +++
> >  net/rds/send.c | 6 +-----
> >  2 files changed, 4 insertions(+), 5 deletions(-)
> > 
> > diff --git a/net/rds/rdma.c b/net/rds/rdma.c
> > index fba82d36593a..a4e3c5de998b 100644
> > --- a/net/rds/rdma.c
> > +++ b/net/rds/rdma.c
> > @@ -301,6 +301,9 @@ static int __rds_rdma_map(struct rds_sock *rs, struct rds_get_mr_args *args,
> >  			kfree(sg);
> >  		}
> >  		ret = PTR_ERR(trans_private);
> > +		/* Trigger connection so that its ready for the next retry */
> > +		if (ret == -ENODEV)
> > +			rds_conn_connect_if_down(cp->cp_conn);
> 
> Hi Edward,
> 
> Elsewhere in this function it is assumed that cp may be NULL.
> Does that need to be taken into account here too?
Don't worry about this, if it is NULL, the get_mr() return value will not be -ENODEV.
> 
> Flagged by Smatch.
> 
> >  		goto out;
> >  	}
> >  
> > diff --git a/net/rds/send.c b/net/rds/send.c
> > index 5e57a1581dc6..fa1640628b2f 100644
> > --- a/net/rds/send.c
> > +++ b/net/rds/send.c
> > @@ -1313,12 +1313,8 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
> >  
> >  	/* Parse any control messages the user may have included. */
> >  	ret = rds_cmsg_send(rs, rm, msg, &allocated_mr, &vct);
> > -	if (ret) {
> > -		/* Trigger connection so that its ready for the next retry */
> > -		if (ret ==  -EAGAIN)
> > -			rds_conn_connect_if_down(conn);
> > +	if (ret) 
> 
> nit: checkpatch warns that there is a trailing space on the line above.
I will send a V2 version patch to correct this warning.

BR,
Edward