On Mon, Mar 15, 2021 at 4:42 PM David Miller <da...@redhat.com> wrote: > > From: Yunsheng Lin <linyunsh...@huawei.com> > Date: Mon, 15 Mar 2021 17:30:10 +0800 > > > Currently qdisc_lock(q) is taken before enqueuing and dequeuing > > for lockless qdisc's skb_bad_txq/gso_skb queue, qdisc->seqlock is > > also taken, which can provide the same protection as qdisc_lock(q). > > > > This patch removes the unnecessay qdisc_lock(q) protection for > > lockless qdisc' skb_bad_txq/gso_skb queue. > > > > And dev_reset_queue() takes the qdisc->seqlock for lockless qdisc > > besides taking the qdisc_lock(q) when doing the qdisc reset, > > some_qdisc_is_busy() takes both qdisc->seqlock and qdisc_lock(q) > > when checking qdisc status. It is unnecessary to take both lock > > while the fast path only take one lock, so this patch also changes > > it to only take qdisc_lock(q) for locked qdisc, and only take > > qdisc->seqlock for lockless qdisc. > > > > Since qdisc->seqlock is taken for lockless qdisc when calling > > qdisc_is_running() in some_qdisc_is_busy(), use qdisc->running > > to decide if the lockless qdisc is running. > > > > Signed-off-by: Yunsheng Lin <linyunsh...@huawei.com> > > What about other things protected by this lock, such as statistics and qlen? > > This change looks too risky to me.
They are per-cpu for pfifo_fast which sets TCQ_F_CPUSTATS too. Thanks.
