On Mon, 25 Oct 2010 13:46:32 -0400
"J. Bruce Fields" <bfields@xxxxxxxxxx> wrote:
> On Mon, Oct 25, 2010 at 11:03:08AM -0400, J. Bruce Fields wrote:
> > On Mon, Oct 25, 2010 at 01:10:24PM +1100, Neil Brown wrote:
> > > On Sun, 24 Oct 2010 21:21:33 -0400
> > > "J. Bruce Fields" <bfields@xxxxxxxxxx> wrote:
> > >
> > > > The only caller (svc_send) has already checked XPT_DEAD.
> > > >
> > > > Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
> > > > ---
> > > > net/sunrpc/svcsock.c | 3 ---
> > > > 1 files changed, 0 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
> > > > index 1454739..07919e1 100644
> > > > --- a/net/sunrpc/svcsock.c
> > > > +++ b/net/sunrpc/svcsock.c
> > > > @@ -1135,9 +1135,6 @@ static int svc_tcp_sendto(struct svc_rqst *rqstp)
> > > > reclen = htonl(0x80000000|((xbufp->len ) - 4));
> > > > memcpy(xbufp->head[0].iov_base, &reclen, 4);
> > > >
> > > > - if (test_bit(XPT_DEAD, &rqstp->rq_xprt->xpt_flags))
> > > > - return -ENOTCONN;
> > > > -
> > > > sent = svc_sendto(rqstp, &rqstp->rq_res);
> > > > if (sent != xbufp->len) {
> > > > printk(KERN_NOTICE
> > >
> > >
> > > So after removing all these references to XPT_DEAD, do we need XPT_DEAD at
> > > all???
> > >
> > > I think it is only used in two other places.
> > >
> > > 1/ In svc_revisit we don't queue the deferred request to an XPT_DEAD
> > > transport.
> > > We could avoid that but changing the 'owner' of a deferred request from the
> > > service to the xprt, and call cache_clean_deferred in svc_delete_xprt
> >
> > That use does seem a bit of a hack to me, so I'd be happy to get rid of
> > it.
>
> Eh, but then don't we end up doing the same check when deferring, to
> prevent deferring a request on a dead xprt?
Good point.
However....
If we change svc_defer to set handle.owner to rqstp->rq_xprt rather than
rqstp->rq_server (As already suggested), then we don't need the svc_xprt_get.
i.e. the deferred request doesn't need to hold a reference to the xprt,
because when the xprt is finally removed it is easy (cache_clean_deferred) to
remove all those deferred requests.
So we put the call to cache_clean_deferred in svc_xprt_free. By this stage
we are guaranteed not to get more deferrals as the xprt is dead.
>
> Maybe we should leave well enough alone here.
That is certainly an option, especially if it turns out that we cannot remove
XPT_DEAD completely.
Thanks,
NeilBrown
>
> --b.
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