On Mon, 23 Nov 2020 10:52:52 -0800
Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
> On Mon, 23 Nov 2020 09:31:28 -0500 Steven Rostedt wrote:
> > On Mon, 23 Nov 2020 13:08:55 +0200
> > Leon Romanovsky <leon@xxxxxxxxxx> wrote:
> >
> >
> > > [ 10.028024] Chain exists of:
> > > [ 10.028025] console_owner --> target_list_lock --> _xmit_ETHER#2
> >
> > Note, the problem is that we have a location that grabs the xmit_lock while
> > holding target_list_lock (and possibly console_owner).
>
> Well, it try_locks the xmit_lock. Does lockdep understand try-locks?
>
> (not that I condone the shenanigans that are going on here)
Does it?
virtnet_poll_tx() {
__netif_tx_lock() {
spin_lock(&txq->_xmit_lock);
That looks like we can have:
CPU0 CPU1
---- ----
lock(xmit_lock)
lock(console)
lock(target_list_lock)
__netif_tx_lock()
lock(xmit_lock);
[BLOCKED]
<interrupt>
lock(console)
[BLOCKED]
DEADLOCK.
So where is the trylock here?
Perhaps you need the trylock in virtnet_poll_tx()?
-- Steve
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