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

[Simon Horman <horms@kernel.org>]

On Sun, Mar 03, 2024 at 12:18:57PM +0800, Edward Adam Davis 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?

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.

>  		goto out;
> -	}
>  
>  	if (rm->rdma.op_active && !conn->c_trans->xmit_rdma) {
>  		printk_ratelimited(KERN_NOTICE "rdma_op %p conn xmit_rdma %p\n",

-- 
pw-bot: changes-requested