[lustre-devel] [PATCH 22/34] lnet: don't take reference in lnet_XX2ni_locked()

From: Doug Oucharek <doucharek@cray.com>
To: lustre-devel@lists.lustre.org
Subject: [lustre-devel] [PATCH 22/34] lnet: don't take reference in lnet_XX2ni_locked()
Date: Wed, 12 Sep 2018 04:18:21 +0000	[thread overview]
Message-ID: <3D26740D-2ABC-4596-BDF1-D3E2F186608A@cray.com> (raw)
In-Reply-To: <153628137211.8267.6066882916704220570.stgit@noble>

Reviewed-by: Doug Oucharek <dougso@me.com>

Doug

?On 9/6/18, 5:54 PM, "NeilBrown" <neilb@suse.com> wrote:

    lnet_net2ni_locked() and lnet_nid2ni_locked() no longer take
    a reference - as the lock is held, a ref isn't always needed.
    
    Instead, introduce lnet_nid2ni_addref() which does take the reference
    (but doesn't need the lock).
    Various places which called lnet_net2ni_locked() or
    lnet_nid2ni_locked() no longer need to drop the ref afterwards.
    
    This is part of
        8cbb8cd3e771e7f7e0f99cafc19fad32770dc015
           LU-7734 lnet: Multi-Rail local NI split
    
    Signed-off-by: NeilBrown <neilb@suse.com>
    ---
     .../staging/lustre/include/linux/lnet/lib-lnet.h   |    1 +
     .../staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c |    2 +
     drivers/staging/lustre/lnet/lnet/acceptor.c        |    2 +
     drivers/staging/lustre/lnet/lnet/api-ni.c          |   27 +++++++++++++-------
     drivers/staging/lustre/lnet/lnet/lib-move.c        |   17 +------------
     5 files changed, 21 insertions(+), 28 deletions(-)
    
    diff --git a/drivers/staging/lustre/include/linux/lnet/lib-lnet.h b/drivers/staging/lustre/include/linux/lnet/lib-lnet.h
    index 54a93235834c..6401d9a37b23 100644
    --- a/drivers/staging/lustre/include/linux/lnet/lib-lnet.h
    +++ b/drivers/staging/lustre/include/linux/lnet/lib-lnet.h
    @@ -398,6 +398,7 @@ extern int avoid_asym_router_failure;
     int lnet_cpt_of_nid_locked(lnet_nid_t nid, struct lnet_ni *ni);
     int lnet_cpt_of_nid(lnet_nid_t nid, struct lnet_ni *ni);
     struct lnet_ni *lnet_nid2ni_locked(lnet_nid_t nid, int cpt);
    +struct lnet_ni *lnet_nid2ni_addref(lnet_nid_t nid);
     struct lnet_ni *lnet_net2ni_locked(__u32 net, int cpt);
     struct lnet_ni *lnet_net2ni(__u32 net);
     bool lnet_is_ni_healthy_locked(struct lnet_ni *ni);
    diff --git a/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c b/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
    index e64c14914924..af8f863b6a68 100644
    --- a/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
    +++ b/drivers/staging/lustre/lnet/klnds/o2iblnd/o2iblnd_cb.c
    @@ -2294,7 +2294,7 @@ kiblnd_passive_connect(struct rdma_cm_id *cmid, void *priv, int priv_nob)
     	}
     
     	nid = reqmsg->ibm_srcnid;
    -	ni = lnet_net2ni(LNET_NIDNET(reqmsg->ibm_dstnid));
    +	ni = lnet_nid2ni_addref(reqmsg->ibm_dstnid);
     
     	if (ni) {
     		net = (struct kib_net *)ni->ni_data;
    diff --git a/drivers/staging/lustre/lnet/lnet/acceptor.c b/drivers/staging/lustre/lnet/lnet/acceptor.c
    index 88b90c1fdbaf..25205f686801 100644
    --- a/drivers/staging/lustre/lnet/lnet/acceptor.c
    +++ b/drivers/staging/lustre/lnet/lnet/acceptor.c
    @@ -296,7 +296,7 @@ lnet_accept(struct socket *sock, __u32 magic)
     	if (flip)
     		__swab64s(&cr.acr_nid);
     
    -	ni = lnet_net2ni(LNET_NIDNET(cr.acr_nid));
    +	ni = lnet_nid2ni_addref(cr.acr_nid);
     	if (!ni ||	       /* no matching net */
     	    ni->ni_nid != cr.acr_nid) { /* right NET, wrong NID! */
     		if (ni)
    diff --git a/drivers/staging/lustre/lnet/lnet/api-ni.c b/drivers/staging/lustre/lnet/lnet/api-ni.c
    index ce3dd0f32e12..42e775e2a669 100644
    --- a/drivers/staging/lustre/lnet/lnet/api-ni.c
    +++ b/drivers/staging/lustre/lnet/lnet/api-ni.c
    @@ -655,7 +655,6 @@ lnet_net2ni_locked(__u32 net_id, int cpt)
     		if (net->net_id == net_id) {
     			ni = list_entry(net->net_ni_list.next, struct lnet_ni,
     					ni_netlist);
    -			lnet_ni_addref_locked(ni, cpt);
     			return ni;
     		}
     	}
    @@ -794,16 +793,29 @@ lnet_nid2ni_locked(lnet_nid_t nid, int cpt)
     
     	list_for_each_entry(net, &the_lnet.ln_nets, net_list) {
     		list_for_each_entry(ni, &net->net_ni_list, ni_netlist) {
    -			if (ni->ni_nid == nid) {
    -				lnet_ni_addref_locked(ni, cpt);
    +			if (ni->ni_nid == nid)
     				return ni;
    -			}
     		}
     	}
     
     	return NULL;
     }
     
    +struct lnet_ni *
    +lnet_nid2ni_addref(lnet_nid_t nid)
    +{
    +	struct lnet_ni *ni;
    +
    +	lnet_net_lock(0);
    +	ni = lnet_nid2ni_locked(nid, 0);
    +	if (ni)
    +		lnet_ni_addref_locked(ni, 0);
    +	lnet_net_unlock(0);
    +
    +	return ni;
    +}
    +EXPORT_SYMBOL(lnet_nid2ni_addref);
    +
     int
     lnet_islocalnid(lnet_nid_t nid)
     {
    @@ -812,8 +824,6 @@ lnet_islocalnid(lnet_nid_t nid)
     
     	cpt = lnet_net_lock_current();
     	ni = lnet_nid2ni_locked(nid, cpt);
    -	if (ni)
    -		lnet_ni_decref_locked(ni, cpt);
     	lnet_net_unlock(cpt);
     
     	return !!ni;
    @@ -1412,6 +1422,7 @@ lnet_startup_lndnet(struct lnet_net *net, struct lnet_lnd_tunables *tun)
     		if (rc < 0)
     			goto failed1;
     
    +		lnet_ni_addref(ni);
     		list_add_tail(&ni->ni_netlist, &local_ni_list);
     
     		ni_count++;
    @@ -2032,9 +2043,6 @@ lnet_dyn_del_ni(__u32 net)
     		goto failed;
     	}
     
    -	/* decrement the reference counter taken by lnet_net2ni() */
    -	lnet_ni_decref_locked(ni, 0);
    -
     	lnet_shutdown_lndni(ni);
     
     	if (!lnet_count_acceptor_nets())
    @@ -2264,7 +2272,6 @@ LNetCtl(unsigned int cmd, void *arg)
     		else
     			rc = ni->ni_net->net_lnd->lnd_ctl(ni, cmd, arg);
     
    -		lnet_ni_decref(ni);
     		return rc;
     	}
     	/* not reached */
    diff --git a/drivers/staging/lustre/lnet/lnet/lib-move.c b/drivers/staging/lustre/lnet/lnet/lib-move.c
    index 00a89221c9b3..60f34c4b85d3 100644
    --- a/drivers/staging/lustre/lnet/lnet/lib-move.c
    +++ b/drivers/staging/lustre/lnet/lnet/lib-move.c
    @@ -1127,11 +1127,7 @@ lnet_send(lnet_nid_t src_nid, struct lnet_msg *msg, lnet_nid_t rtr_nid)
     		if (!src_ni) {
     			src_ni = local_ni;
     			src_nid = src_ni->ni_nid;
    -		} else if (src_ni == local_ni) {
    -			lnet_ni_decref_locked(local_ni, cpt);
    -		} else {
    -			lnet_ni_decref_locked(local_ni, cpt);
    -			lnet_ni_decref_locked(src_ni, cpt);
    +		} else if (src_ni != local_ni) {
     			lnet_net_unlock(cpt);
     			LCONSOLE_WARN("No route to %s via from %s\n",
     				      libcfs_nid2str(dst_nid),
    @@ -1149,16 +1145,10 @@ lnet_send(lnet_nid_t src_nid, struct lnet_msg *msg, lnet_nid_t rtr_nid)
     			/* No send credit hassles with LOLND */
     			lnet_net_unlock(cpt);
     			lnet_ni_send(src_ni, msg);
    -
    -			lnet_net_lock(cpt);
    -			lnet_ni_decref_locked(src_ni, cpt);
    -			lnet_net_unlock(cpt);
     			return 0;
     		}
     
     		rc = lnet_nid2peer_locked(&lp, dst_nid, cpt);
    -		/* lp has ref on src_ni; lose mine */
    -		lnet_ni_decref_locked(src_ni, cpt);
     		if (rc) {
     			lnet_net_unlock(cpt);
     			LCONSOLE_WARN("Error %d finding peer %s\n", rc,
    @@ -1173,8 +1163,6 @@ lnet_send(lnet_nid_t src_nid, struct lnet_msg *msg, lnet_nid_t rtr_nid)
     					    src_ni->ni_net : NULL,
     					    dst_nid, rtr_nid);
     		if (!lp) {
    -			if (src_ni)
    -				lnet_ni_decref_locked(src_ni, cpt);
     			lnet_net_unlock(cpt);
     
     			LCONSOLE_WARN("No route to %s via %s (all routers down)\n",
    @@ -1192,8 +1180,6 @@ lnet_send(lnet_nid_t src_nid, struct lnet_msg *msg, lnet_nid_t rtr_nid)
     		if (rtr_nid != lp->lp_nid) {
     			cpt2 = lp->lp_cpt;
     			if (cpt2 != cpt) {
    -				if (src_ni)
    -					lnet_ni_decref_locked(src_ni, cpt);
     				lnet_net_unlock(cpt);
     
     				rtr_nid = lp->lp_nid;
    @@ -1212,7 +1198,6 @@ lnet_send(lnet_nid_t src_nid, struct lnet_msg *msg, lnet_nid_t rtr_nid)
     			src_nid = src_ni->ni_nid;
     		} else {
     			LASSERT(src_ni->ni_net == lp->lp_net);
    -			lnet_ni_decref_locked(src_ni, cpt);
     		}
     
     		lnet_peer_addref_locked(lp);