On Mon, May 21, 2018 at 1:03 PM, Vlad Buslov <vla...@mellanox.com> wrote:
> Initial net_device implementation used ingress_lock spinlock to synchronize
> ingress path of device. This lock was used in both process and bh context.
> In some code paths action map lock was obtained while holding ingress_lock.
> Commit e1e992e52faa ("[NET_SCHED] protect action config/dump from irqs")
> modified actions to always disable bh, while using action map lock, in
> order to prevent deadlock on ingress_lock in softirq. This lock was removed
> from net_device, so disabling bh, while accessing action map, is no longer
> necessary.
>
> Replace all action idr spinlock usage with regular calls that do not
> disable bh.While your patch is probably fine, the above justification seems not. In the past, tc actions could be released in BH context because tc filters use call_rcu(). However, I moved them to a workqueue recently. So before my change I don't think you can remove the BH protection, otherwise race with idr_remove()...
