[PATCH net-next 2/8] net/smc: terminate link group without holding lgr lock

[Karsten Graul]

From: Ursula Braun <ubr...@linux.ibm.com>

When a link group is to be terminated, it is sufficient to hold
the lgr lock when unlinking the link group from its list.
Move the lock-protected link group unlinking into smc_lgr_terminate().

Signed-off-by: Ursula Braun <ubr...@linux.ibm.com>
Signed-off-by: Karsten Graul <kgr...@linux.ibm.com>
---
 net/smc/smc_core.c | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 4ee0e33b8c5a..b53ba8f0a833 100644
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -182,8 +182,7 @@ static void smc_lgr_free_work(struct work_struct *work)
                spin_unlock_bh(lgr_lock);
                return;
        }
-       if (!list_empty(&lgr->list))
-               list_del_init(&lgr->list); /* remove from smc_lgr_list */
+       list_del_init(&lgr->list); /* remove from smc_lgr_list */
        spin_unlock_bh(lgr_lock);
 
        if (!lgr->is_smcd && !lgr->terminating) {
@@ -479,7 +478,7 @@ void smc_lgr_forget(struct smc_link_group *lgr)
        spin_unlock_bh(lgr_lock);
 }
 
-/* terminate linkgroup abnormally */
+/* terminate link group */
 static void __smc_lgr_terminate(struct smc_link_group *lgr)
 {
        struct smc_connection *conn;
@@ -489,8 +488,6 @@ static void __smc_lgr_terminate(struct smc_link_group *lgr)
        if (lgr->terminating)
                return; /* lgr already terminating */
        lgr->terminating = 1;
-       if (!list_empty(&lgr->list)) /* forget lgr */
-               list_del_init(&lgr->list);
        if (!lgr->is_smcd)
                smc_llc_link_inactive(&lgr->lnk[SMC_SINGLE_LINK]);
 
@@ -516,29 +513,41 @@ static void __smc_lgr_terminate(struct smc_link_group 
*lgr)
        smc_lgr_schedule_free_work(lgr);
 }
 
+/* unlink and terminate link group */
 void smc_lgr_terminate(struct smc_link_group *lgr)
 {
        spinlock_t *lgr_lock;
 
        smc_lgr_list_head(lgr, &lgr_lock);
        spin_lock_bh(lgr_lock);
-       __smc_lgr_terminate(lgr);
+       if (lgr->terminating) {
+               spin_unlock_bh(lgr_lock);
+               return; /* lgr already terminating */
+       }
+       list_del_init(&lgr->list);
        spin_unlock_bh(lgr_lock);
+       __smc_lgr_terminate(lgr);
 }
 
 /* Called when IB port is terminated */
 void smc_port_terminate(struct smc_ib_device *smcibdev, u8 ibport)
 {
        struct smc_link_group *lgr, *l;
+       LIST_HEAD(lgr_free_list);
 
        spin_lock_bh(&smc_lgr_list.lock);
        list_for_each_entry_safe(lgr, l, &smc_lgr_list.list, list) {
                if (!lgr->is_smcd &&
                    lgr->lnk[SMC_SINGLE_LINK].smcibdev == smcibdev &&
                    lgr->lnk[SMC_SINGLE_LINK].ibport == ibport)
-                       __smc_lgr_terminate(lgr);
+                       list_move(&lgr->list, &lgr_free_list);
        }
        spin_unlock_bh(&smc_lgr_list.lock);
+
+       list_for_each_entry_safe(lgr, l, &lgr_free_list, list) {
+               list_del_init(&lgr->list);
+               __smc_lgr_terminate(lgr);
+       }
 }
 
 /* Called when SMC-D device is terminated or peer is lost */
@@ -552,7 +561,6 @@ void smc_smcd_terminate(struct smcd_dev *dev, u64 peer_gid, 
unsigned short vlan)
        list_for_each_entry_safe(lgr, l, &dev->lgr_list, list) {
                if ((!peer_gid || lgr->peer_gid == peer_gid) &&
                    (vlan == VLAN_VID_MASK || lgr->vlan_id == vlan)) {
-                       __smc_lgr_terminate(lgr);
                        list_move(&lgr->list, &lgr_free_list);
                }
        }
@@ -561,6 +569,7 @@ void smc_smcd_terminate(struct smcd_dev *dev, u64 peer_gid, 
unsigned short vlan)
        /* cancel the regular free workers and actually free lgrs */
        list_for_each_entry_safe(lgr, l, &lgr_free_list, list) {
                list_del_init(&lgr->list);
+               __smc_lgr_terminate(lgr);
                cancel_delayed_work_sync(&lgr->free_work);
                if (!peer_gid && vlan == VLAN_VID_MASK) /* dev terminated? */
                        smc_ism_signal_shutdown(lgr);
-- 
2.17.1