Messages in this thread | | | From | Xie He <> | Date | Thu, 11 Mar 2021 13:12:25 -0800 | Subject | Re: [PATCH net] net: lapbether: Prevent racing when checking whether the netif is running |
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On Thu, Mar 11, 2021 at 12:43 PM Jakub Kicinski <kuba@kernel.org> wrote: > > Is this a theoretical issues or do you see a path where it triggers? > > Who are the callers sending frames to a device which went down?
This is a theoretical issue. I didn't see this issue in practice.
When "__dev_queue_xmit" and "sch_direct_xmit" call "dev_hard_start_xmit", there appears to be no locking mechanism preventing the netif from going down while "dev_hard_start_xmit" is doing its work.
David once confirmed in an email that a driver's "ndo_stop" function would indeed race with its "ndo_start_xmit" function: https://lore.kernel.org/netdev/20190520.200922.2277656639346033061.davem@davemloft.net/
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