RE: [PATCH net-next] net: sch: prio: Set bands to default on delete instead of noop
> > When a band is created, it is set to the default qdisc, which is
> > "invisible" pfifo.
> > However, if a band is set to a qdisc that is later being deleted, it will
> > be set to noop qdisc. This can cause a packet loss, while there is no clear
> > user indication for it. ("invisible" qdisc are not being shown by default).
> > This patch sets a band to the default qdisc, rather then the noop qdisc, on
> > delete operation.
> >
> > Signed-off-by: Nogah Frankel
>
> Like Cong, I'm worried this will break something. The code has
> behaved this way for 2 decades or longer.
>
> If you want to put another qdisc there, and thus not drop any traffic,
> modify the qdisc to a new one instead of performing a delete operation.
I believe that this historic behavior is quite bug like, especially because
TCA_DUMP_INVISIBLE is not set by default.
Yet I accept your judgment that changing it now might break things.
Thank you.
Nogah
Re: [PATCH net-next] net: sch: prio: Set bands to default on delete instead of noop
From: Nogah Frankel
Date: Thu, 26 Apr 2018 16:32:36 +0300
> When a band is created, it is set to the default qdisc, which is
> "invisible" pfifo.
> However, if a band is set to a qdisc that is later being deleted, it will
> be set to noop qdisc. This can cause a packet loss, while there is no clear
> user indication for it. ("invisible" qdisc are not being shown by default).
> This patch sets a band to the default qdisc, rather then the noop qdisc, on
> delete operation.
>
> Signed-off-by: Nogah Frankel
Like Cong, I'm worried this will break something. The code has
behaved this way for 2 decades or longer.
If you want to put another qdisc there, and thus not drop any traffic,
modify the qdisc to a new one instead of performing a delete operation.
Re: [PATCH net-next] net: sch: prio: Set bands to default on delete instead of noop
On Thu, Apr 26, 2018 at 6:32 AM, Nogah Frankel wrote:
> When a band is created, it is set to the default qdisc, which is
> "invisible" pfifo.
Isn't TCA_DUMP_INVISIBLE for dumping this invisible qdisc?
> However, if a band is set to a qdisc that is later being deleted, it will
> be set to noop qdisc. This can cause a packet loss, while there is no clear
> user indication for it. ("invisible" qdisc are not being shown by default).
> This patch sets a band to the default qdisc, rather then the noop qdisc, on
> delete operation.
It is set to noop historically, may be not reasonable but changing
it could break things.
What's wrong with using TCA_DUMP_INVISIBLE to dump it?
