On Thu, Jul 17, 2014 at 09:24:13PM +0800, Kinglong Mee wrote:
> On 7/17/2014 06:05, J. Bruce Fields wrote:
> > On Sat, Jul 12, 2014 at 10:02:17PM +0800, Kinglong Mee wrote:
> >> On 7/12/2014 05:16, J. Bruce Fields wrote:
> >>> The local variable "ses" will be left NULL here in the case we fail to
> >>> find a connection. Spotted by a coverity scan.
> >>>
> >>> Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
> >>>
> >>> diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
> >>> index 2c73cae9899d..fe22cd5c42d3 100644
> >>> --- a/fs/nfsd/nfs4callback.c
> >>> +++ b/fs/nfsd/nfs4callback.c
> >>> @@ -1001,14 +1001,18 @@ static void nfsd4_process_cb_update(struct nfsd4_callback *cb)
> >>> }
> >>> spin_unlock(&clp->cl_lock);
> >>>
> >>> + if (!c)
> >>> + goto out_no_connection;
> >>
> >> Setting err to -EINVAL maybe better.
> >> Otherwise, nfsd4_mark_cb_down will be called with err == 0.
> >>
> >>> err = setup_callback_client(clp, &conn, ses);
> >>
> >> setup_callback_client also return -EINVAL when ses == NULL with conn.cb_xprt == NULL.
> >
> > Thanks, yes, after looking over this carefully I don't believe we can
> > call setup_callback_client with ses NULL but conn->cb_xprt non-NULL, so
> > this is just a false positive from coverity.
>
> ses and conn->cb_xprt will be set in the same condition before
> calling setup_callback_client,
>
> 996 c = __nfsd4_find_backchannel(clp);
> 997 if (c) {
> 998 svc_xprt_get(c->cn_xprt);
> 999 conn.cb_xprt = c->cn_xprt;
> 1000 ses = c->cn_session;
> 1001 }
> 1002 spin_unlock(&clp->cl_lock);
> 1003
> 1004 err = setup_callback_client(clp, &conn, ses);
>
> ses and conn->cb_xprt will be NULL or non-NULL in the same time,
> so that, call setup_calback_client with ses NULL but conn->cb_xprt non-NULL will not appear.
Agreed but you also need to check what happens in the case where c is
NULL.
This is much more confusing than necessary. But I'm inclined to hold
off on any cleanup here while jlayton's patches are still pending.
--b.
>
> thanks,
> Kinglong Mee
>
> >>> - if (err) {
> >>> - nfsd4_mark_cb_down(clp, err);
> >>> - return;
> >>> - }
> >>> + if (err)
> >>> + goto out_no_connection;
> >>> /* Yay, the callback channel's back! Restart any callbacks: */
> >>> list_for_each_entry(cb, &clp->cl_callbacks, cb_per_client)
> >>> run_nfsd4_cb(cb);
> >>> + return;
> >>> +out_no_connection:
> >>> + nfsd4_mark_cb_down(clp, err);
> >>> + return;
> >>> }
> >>>
> >>> static void nfsd4_do_callback_rpc(struct work_struct *w)
> >>> --
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> >>>
> >
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