| Message ID | 20220826013930.340121-1-shaozhengchao@huawei.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | b05972f01e7d30419987a1f221b5593668fd6448 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v2] net: sched: tbf: don't call qdisc_put() while holding tree lock | expand |
Hello: This patch was applied to netdev/net.git (master) by Paolo Abeni <pabeni@redhat.com>: On Fri, 26 Aug 2022 09:39:30 +0800 you wrote: > The issue is the same to commit c2999f7fb05b ("net: sched: multiq: don't > call qdisc_put() while holding tree lock"). Qdiscs call qdisc_put() while > holding sch tree spinlock, which results sleeping-while-atomic BUG. > > Fixes: c266f64dbfa2 ("net: sched: protect block state with mutex") > Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> > > [...] Here is the summary with links: - [net,v2] net: sched: tbf: don't call qdisc_put() while holding tree lock https://git.kernel.org/netdev/net/c/b05972f01e7d You are awesome, thank you!
On Fri, Aug 26, 2022 at 09:39:30AM +0800, Zhengchao Shao wrote: > The issue is the same to commit c2999f7fb05b ("net: sched: multiq: don't > call qdisc_put() while holding tree lock"). Qdiscs call qdisc_put() while > holding sch tree spinlock, which results sleeping-while-atomic BUG. > Hm, did you see an actual warning here?? The commit you mentioned above is a classful Qdisc which accepts user-specified child Qdisc, but TBF technically does not, I don't think you can change its default fifo. Thanks.
On 2022/9/6 2:13, Cong Wang wrote: > On Fri, Aug 26, 2022 at 09:39:30AM +0800, Zhengchao Shao wrote: >> The issue is the same to commit c2999f7fb05b ("net: sched: multiq: don't >> call qdisc_put() while holding tree lock"). Qdiscs call qdisc_put() while >> holding sch tree spinlock, which results sleeping-while-atomic BUG. >> > > Hm, did you see an actual warning here?? > > The commit you mentioned above is a classful Qdisc which accepts > user-specified child Qdisc, but TBF technically does not, I don't think > you can change its default fifo. > > Thanks. Hi Wang: Thank you for your reply. My apologise. I don't see the warning here. Yes, TBF is classless qdisc, its default fifo is bfifo and reset or destroy process will not sleep. So, it's not a issue. Should I revert it, or keep it in this format(qdisc_put out of holding sch tree spinlock). Zhengchao Shao
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c index 72102277449e..36079fdde2cb 100644 --- a/net/sched/sch_tbf.c +++ b/net/sched/sch_tbf.c @@ -356,6 +356,7 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt, struct nlattr *tb[TCA_TBF_MAX + 1]; struct tc_tbf_qopt *qopt; struct Qdisc *child = NULL; + struct Qdisc *old = NULL; struct psched_ratecfg rate; struct psched_ratecfg peak; u64 max_size; @@ -447,7 +448,7 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt, sch_tree_lock(sch); if (child) { qdisc_tree_flush_backlog(q->qdisc); - qdisc_put(q->qdisc); + old = q->qdisc; q->qdisc = child; } q->limit = qopt->limit; @@ -467,6 +468,7 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt, memcpy(&q->peak, &peak, sizeof(struct psched_ratecfg)); sch_tree_unlock(sch); + qdisc_put(old); err = 0; tbf_offload_change(sch);
The issue is the same to commit c2999f7fb05b ("net: sched: multiq: don't call qdisc_put() while holding tree lock"). Qdiscs call qdisc_put() while holding sch tree spinlock, which results sleeping-while-atomic BUG. Fixes: c266f64dbfa2 ("net: sched: protect block state with mutex") Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> --- v1: The subject needs to be changed to [PATCH net]. --- net/sched/sch_tbf.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)