| Message ID | 20190227101226.26196-10-vladbu@mellanox.com |
|---|---|
| State | Deferred |
| Delegated to: | David Miller |
| Headers | show |
| Series | Refactor flower classifier to remove dependency on rtnl lock | expand |
diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c index 70b357f23391..25a4d64b82db 100644 --- a/net/sched/cls_flower.c +++ b/net/sched/cls_flower.c @@ -1500,6 +1500,14 @@ static int fl_change(struct net *net, struct sk_buff *in_skb, if (!tc_in_hw(fnew->flags)) fnew->flags |= TCA_CLS_FLAGS_NOT_IN_HW; + /* tp was deleted concurrently. -EAGAIN will cause caller to lookup + * proto again or create new one, if necessary. + */ + if (tp->deleting) { + err = -EAGAIN; + goto errout_hw; + } + refcount_inc(&fnew->refcnt); if (fold) { /* Fold filter was deleted concurrently. Retry lookup. */
Without rtnl lock protection tcf proto can be deleted concurrently. Check tcf proto 'deleting' flag after taking tcf spinlock to verify that no concurrent deletion is in progress. Return EAGAIN error if concurrent deletion detected, which will cause caller to retry and possibly create new instance of tcf proto. Retry mechanism is a result of fine-grained locking approach used in this and previous changes in series and is necessary to allow concurrent updates on same chain instance. Alternative approach would be to lock the whole chain while updating filters on any of child tp's, adding and removing classifier instances from the chain. However, since most CPU-intensive parts of filter update code are specifically in classifier code and its dependencies (extensions and hw offloads), such approach would negate most of the gains introduced by this change and previous changes in the series when updating same chain instance. Signed-off-by: Vlad Buslov <vladbu@mellanox.com> --- Changes from V1 to V2: - Extend commit message. - Fix error code in comment. net/sched/cls_flower.c | 8 ++++++++ 1 file changed, 8 insertions(+)