> On Wed, 2019-07-10 at 17:47 +0000, Lee Duncan wrote:
> > On 7/10/19 12:30 AM, Yang Bin wrote:
> >
> > > From: " Yang Bin "<yang.bi...@zte.com.cn>
> > >
> > > Before xmit,iscsi may disconnect just now.
> > > So must check connection sock NULL or not,or kernel will crash for
> > > accessing NULL pointer.
> > >
> > > Signed-off-by: Yang Bin <yang.bi...@zte.com.cn>
> > > ---
> > > drivers/scsi/iscsi_tcp.c | 3 +++
> > > 1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
> > > index 7bedbe8..a59c49f 100644
> > > --- a/drivers/scsi/iscsi_tcp.c
> > > +++ b/drivers/scsi/iscsi_tcp.c
> > > @@ -264,6 +264,9 @@ static int iscsi_sw_tcp_xmit_segment(struct
> > > iscsi_tcp_conn *tcp_conn,
> > > unsigned int copied = 0;
> > > int r = 0;
> > >
> > > + if (!sk)
> > > + return -ENOTCONN;
> > > +
> > > while (!iscsi_tcp_segment_done(tcp_conn, segment, 0, r)) {
> > > struct scatterlist *sg;
> > > unsigned int offset, copy;
> > >
> >
> > If the socket can be closed right before iscsi_sw_tcp_xmit_segment()
> > is called, can it be called in the middle of sending segments? (In
> > which case the check would have to be in the while loop.)
> I think the important point is: is this an actual observed bug or just
> a theoretical problem?
> The reason for asking is this call is controlled directly by the
> ISCSI_UEVENT_DESTROY_CONN event sent by the iscsi daemon. Obviously if
> the daemon goes haywire and doesn't shut down the connection before
> sending the destroy event, we may get the crash, but I would be
> inclined to say fix the daemon.
> James
We have repproduced this bug several times .
It`s a good idea that sending ISCSI_UEVENT_STOP_CONN event first.
But there is another choice , adding "iscsi_suspend_tx" int the front of
"destroy" ,
for not increasing dependence between kernel and daemon.
Yangbin
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