Re: [PATCH] net: Revert "net_sched: no need to free qdisc in RCU callback"

2017-12-22 Thread Jiri Pirko
Thu, Dec 21, 2017 at 09:59:56PM CET, xiyou.wangc...@gmail.com wrote: >On Thu, Dec 21, 2017 at 12:39 AM, Jiri Pirko wrote: >> >> Why just moving qdisc_free to rcu is not enough? It would resolve this >> issue and also avoid using synchronize net. Something like: > >If you mean Jakub's issue, appare

Re: [PATCH] net: Revert "net_sched: no need to free qdisc in RCU callback"

2017-12-21 Thread Cong Wang
On Thu, Dec 21, 2017 at 12:39 AM, Jiri Pirko wrote: > > Why just moving qdisc_free to rcu is not enough? It would resolve this > issue and also avoid using synchronize net. Something like: If you mean Jakub's issue, apparently not: https://www.kernel.org/pub/linux/kernel/people/paulmck/Answers/RC

Re: [PATCH] net: Revert "net_sched: no need to free qdisc in RCU callback"

2017-12-21 Thread Jiri Pirko
Thu, Dec 21, 2017 at 12:34:05AM CET, john.fastab...@gmail.com wrote: >On 12/20/2017 03:23 PM, Cong Wang wrote: >> On Wed, Dec 20, 2017 at 3:05 PM, John Fastabend >> wrote: >>> On 12/20/2017 02:41 PM, Cong Wang wrote: On Wed, Dec 20, 2017 at 12:09 PM, John Fastabend wrote: > RCU grac

Re: [PATCH] net: Revert "net_sched: no need to free qdisc in RCU callback"

2017-12-20 Thread John Fastabend
On 12/20/2017 01:59 PM, Jakub Kicinski wrote: > On Wed, 20 Dec 2017 12:09:19 -0800, John Fastabend wrote: >> RCU grace period is needed for lockless qdiscs added in the commit >> c5ad119fb6c09 ("net: sched: pfifo_fast use skb_array"). >> >> It is needed now that qdiscs may be lockless otherwise we

Re: [PATCH] net: Revert "net_sched: no need to free qdisc in RCU callback"

2017-12-20 Thread John Fastabend
On 12/20/2017 03:23 PM, Cong Wang wrote: > On Wed, Dec 20, 2017 at 3:05 PM, John Fastabend > wrote: >> On 12/20/2017 02:41 PM, Cong Wang wrote: >>> On Wed, Dec 20, 2017 at 12:09 PM, John Fastabend >>> wrote: RCU grace period is needed for lockless qdiscs added in the commit c5ad119fb6c0

Re: [PATCH] net: Revert "net_sched: no need to free qdisc in RCU callback"

2017-12-20 Thread Cong Wang
On Wed, Dec 20, 2017 at 3:05 PM, John Fastabend wrote: > On 12/20/2017 02:41 PM, Cong Wang wrote: >> On Wed, Dec 20, 2017 at 12:09 PM, John Fastabend >> wrote: >>> RCU grace period is needed for lockless qdiscs added in the commit >>> c5ad119fb6c09 ("net: sched: pfifo_fast use skb_array"). >>> >>

Re: [PATCH] net: Revert "net_sched: no need to free qdisc in RCU callback"

2017-12-20 Thread John Fastabend
On 12/20/2017 02:41 PM, Cong Wang wrote: > On Wed, Dec 20, 2017 at 12:09 PM, John Fastabend > wrote: >> RCU grace period is needed for lockless qdiscs added in the commit >> c5ad119fb6c09 ("net: sched: pfifo_fast use skb_array"). >> >> It is needed now that qdiscs may be lockless otherwise we risk

Re: [PATCH] net: Revert "net_sched: no need to free qdisc in RCU callback"

2017-12-20 Thread Cong Wang
On Wed, Dec 20, 2017 at 12:09 PM, John Fastabend wrote: > RCU grace period is needed for lockless qdiscs added in the commit > c5ad119fb6c09 ("net: sched: pfifo_fast use skb_array"). > > It is needed now that qdiscs may be lockless otherwise we risk > free'ing a qdisc that is still in use from dat

Re: [PATCH] net: Revert "net_sched: no need to free qdisc in RCU callback"

2017-12-20 Thread Jakub Kicinski
On Wed, 20 Dec 2017 12:09:19 -0800, John Fastabend wrote: > RCU grace period is needed for lockless qdiscs added in the commit > c5ad119fb6c09 ("net: sched: pfifo_fast use skb_array"). > > It is needed now that qdiscs may be lockless otherwise we risk > free'ing a qdisc that is still in use from d

[PATCH] net: Revert "net_sched: no need to free qdisc in RCU callback"

2017-12-20 Thread John Fastabend
RCU grace period is needed for lockless qdiscs added in the commit c5ad119fb6c09 ("net: sched: pfifo_fast use skb_array"). It is needed now that qdiscs may be lockless otherwise we risk free'ing a qdisc that is still in use from datapath. Additionally, push list cleanup into RCU callback. Otherwis