Commit 272ffaad authored by Vlad Buslov's avatar Vlad Buslov Committed by David S. Miller

net: sched: flower: handle concurrent tcf proto deletion

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: default avatarVlad Buslov <vladbu@mellanox.com>
Reviewed-by: default avatarStefano Brivio <sbrivio@redhat.com>
Acked-by: default avatarJiri Pirko <jiri@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 9a2d9389
...@@ -1500,6 +1500,14 @@ static int fl_change(struct net *net, struct sk_buff *in_skb, ...@@ -1500,6 +1500,14 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
if (!tc_in_hw(fnew->flags)) if (!tc_in_hw(fnew->flags))
fnew->flags |= TCA_CLS_FLAGS_NOT_IN_HW; 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); refcount_inc(&fnew->refcnt);
if (fold) { if (fold) {
/* Fold filter was deleted concurrently. Retry lookup. */ /* Fold filter was deleted concurrently. Retry lookup. */
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment