On Wed, Jun 12, 2024 at 02:09:35PM -0700, Jakub Kicinski wrote: > On Wed, 12 Jun 2024 08:56:38 +0200 Larysa Zaremba wrote: > > On Tue, Jun 11, 2024 at 07:38:37PM -0700, Jakub Kicinski wrote: > > > On Mon, 10 Jun 2024 17:37:12 +0200 Larysa Zaremba wrote: > > > > Fix the problems that are triggered by tx_timeout and ice_xdp() calls, > > > > including both pool and program operations. > > > > > > Is there really no way for ice to fix the locking? :( > > > The busy loops and trylocks() are not great, and seem like duct tape. > > > > The locking mechanisms I use here do not look pretty, but if I am not > > missing > > anything, the synchronization they provide must be robust. > > Robust as in they may be correct here, but you lose lockdep and all > other infra normal mutex would give you. >
I know, but __netif_queue_set_napi() requires rtnl_lock() inside the potential critical section and creates a deadlock this way. However, after reading patches that introduce this function, I think it is called too early in the configuration. Seems like it should be called somewhere right after netif_set_real_num_rx/_tx_queues(), much later in the configuration where we already hold the rtnl_lock(). In such way, ice_vsi_rebuild() could be protected with an internal mutex. WDYT? > > A prettier way of protecting the same critical sections would be replacing > > ICE_CFG_BUSY around ice_vsi_rebuild() with rtnl_lock(), this would > > eliminate > > locking code from .ndo_bpf() altogether, ice_rebuild_pending() logic will > > have > > to stay. > > > > At some point I have decided to avoid using rtnl_lock(), if I do not have > > to. I > > think this is a goal worth pursuing? > > Is the reset for failure recovery, rather than reconfiguration? > If so netif_device_detach() is generally the best way of avoiding > getting called (I think I mentioned it to someone @intal recently). AFAIK, netif_device_detach() does not affect .ndo_bpf() calls. We were trying such approach with idpf and it does work for ethtool, but not for XDP.
