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SUNRPC: Move svc_xprt_received() call sites 

Currently, XPT_BUSY is not cleared until xpo_recvfrom returns.
That effectively blocks the receipt and handling of the next RPC
message until the current one has been taken off the transport.
This strict ordering is a requirement for socket transports.

For our kernel RPC/RDMA transport implementation, however, dequeuing
an ingress message is nothing more than a list_del(). The transport
can safely be marked un-busy as soon as that is done.

To keep the changes simpler, this patch just moves the
svc_xprt_received() call site from svc_handle_xprt() into the
transports, so that the actual optimization can be done in a
subsequent patch.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2021-01-05 10:15:09 -05:00
parent 7dcfbd86ad
commit 82011c80b3
3 changed files with 17 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
net/sunrpc/svc_xprt.c
View File

@ -820,8 +820,10 @@ static int svc_handle_xprt(struct svc_rqst *rqstp, struct svc_xprt *xprt)
newxpt->xpt_cred = get_cred(xprt->xpt_cred);
svc_add_new_temp_xprt(serv, newxpt);
trace_svc_xprt_accept(newxpt, serv->sv_name);
} else
} else {
module_put(xprt->xpt_class->xcl_owner);
}
svc_xprt_received(xprt);
} else if (svc_xprt_reserve_slot(rqstp, xprt)) {
/* XPT_DATA|XPT_DEFERRED case: */
dprintk("svc: server %p, pool %u, transport %p, inuse=%d\n",
@ -836,8 +838,6 @@ static int svc_handle_xprt(struct svc_rqst *rqstp, struct svc_xprt *xprt)
rqstp->rq_reserved = serv->sv_max_mesg;
atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved);
}
/* clear XPT_BUSY: */
svc_xprt_received(xprt);
out:
trace_svc_handle_xprt(xprt, len);
return len;
@ -1248,6 +1248,7 @@ static noinline int svc_deferred_recv(struct svc_rqst *rqstp)
rqstp->rq_xprt_hlen = dr->xprt_hlen;
rqstp->rq_daddr = dr->daddr;
rqstp->rq_respages = rqstp->rq_pages;
svc_xprt_received(rqstp->rq_xprt);
return (dr->argslen<<2) - dr->xprt_hlen;
}

9
net/sunrpc/svcsock.c
View File

@ -519,6 +519,7 @@ static int svc_udp_recvfrom(struct svc_rqst *rqstp)
if (serv->sv_stats)
serv->sv_stats->netudpcnt++;
svc_xprt_received(rqstp->rq_xprt);
return len;
out_recv_err:
@ -527,7 +528,7 @@ out_recv_err:
set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);
}
trace_svcsock_udp_recv_err(&svsk->sk_xprt, err);
return 0;
goto out_clear_busy;
out_cmsg_err:
net_warn_ratelimited("svc: received unknown control message %d/%d; dropping RPC reply datagram\n",
cmh->cmsg_level, cmh->cmsg_type);
@ -536,6 +537,8 @@ out_bh_enable:
local_bh_enable();
out_free:
kfree_skb(skb);
out_clear_busy:
svc_xprt_received(rqstp->rq_xprt);
return 0;
}
@ -1033,6 +1036,7 @@ static int svc_tcp_recvfrom(struct svc_rqst *rqstp)
if (serv->sv_stats)
serv->sv_stats->nettcpcnt++;
svc_xprt_received(rqstp->rq_xprt);
return rqstp->rq_arg.len;
err_incomplete:
@ -1050,13 +1054,14 @@ error:
if (len != -EAGAIN)
goto err_delete;
trace_svcsock_tcp_recv_eagain(&svsk->sk_xprt, 0);
return 0;
goto err_noclose;
err_nuts:
svsk->sk_datalen = 0;
err_delete:
trace_svcsock_tcp_recv_err(&svsk->sk_xprt, len);
svc_xprt_deferred_close(&svsk->sk_xprt);
err_noclose:
svc_xprt_received(rqstp->rq_xprt);
return 0; /* record not complete */
}

6
net/sunrpc/xprtrdma/svc_rdma_recvfrom.c
View File

@ -846,6 +846,7 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp)
/* No new incoming requests, terminate the loop */
clear_bit(XPT_DATA, &xprt->xpt_flags);
spin_unlock(&rdma_xprt->sc_rq_dto_lock);
svc_xprt_received(xprt);
return 0;
}
list_del(&ctxt->rc_list);
@ -883,28 +884,33 @@ complete:
rqstp->rq_xprt_ctxt = ctxt;
rqstp->rq_prot = IPPROTO_MAX;
svc_xprt_copy_addrs(rqstp, xprt);
svc_xprt_received(xprt);
return rqstp->rq_arg.len;
out_readlist:
ret = svc_rdma_process_read_list(rdma_xprt, rqstp, ctxt);
if (ret < 0)
goto out_readfail;
svc_xprt_received(xprt);
return 0;
out_err:
svc_rdma_send_error(rdma_xprt, ctxt, ret);
svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
svc_xprt_received(xprt);
return 0;
out_readfail:
if (ret == -EINVAL)
svc_rdma_send_error(rdma_xprt, ctxt, ret);
svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
svc_xprt_received(xprt);
return ret;
out_backchannel:
svc_rdma_handle_bc_reply(rqstp, ctxt);
out_drop:
svc_rdma_recv_ctxt_put(rdma_xprt, ctxt);
svc_xprt_received(xprt);
return 0;
}