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Date: Tue, 5 Mar 2024 12:20:45 +0000
From: Simon Horman <horms@kernel.org>
To: Edward Adam Davis <eadavis@qq.com>
Cc: allison.henderson@oracle.com, davem@davemloft.net, edumazet@google.com,
	kuba@kernel.org, linux-kernel@vger.kernel.org,
	linux-rdma@vger.kernel.org, netdev@vger.kernel.org,
	pabeni@redhat.com, rds-devel@oss.oracle.com,
	santosh.shilimkar@oracle.com,
	syzbot+d4faee732755bba9838e@syzkaller.appspotmail.com,
	syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH] net/rds: fix WARNING in rds_conn_connect_if_down
Message-ID: <20240305122045.GB2357@kernel.org>
References: <20240304170707.GJ403078@kernel.org>
 <tencent_A0E364097003A96459B76B577166D5F36505@qq.com>
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In-Reply-To: <tencent_A0E364097003A96459B76B577166D5F36505@qq.com>

On Tue, Mar 05, 2024 at 08:12:03AM +0800, Edward Adam Davis wrote:
> 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.

Thanks, understood.