On Thu, Jul 06, 2023 at 01:54:35PM +0000, Haiyang Zhang wrote: > > This waiting loop is needed to let the pending Tx packets be sent. If > > they weren't sent in 1 second, it most likely makes no sense already > > whether they will be sent at all or not -- the destination host won't > > wait for them for so long. > > You say that it may happen only in case of HW issue. If so, I assume you > > need to fix it some way, e.g. do a HW reset or so? If so, why bother > > waiting for Tx completions if Tx is hung? You free all skbs later either > > way, so there are no leaks. > > At that point, we don't actually care if the pending packets are sent or not. > But if we free the queues too soon, and the HW is slow for unexpected > reasons, a delayed completion notice will DMA into the freed memory and > cause corruption. That's why we have a longer waiting time. Aieiiie that is a horrible HW design to not have a strong fence of DMA. "just wait and hope the HW doesn't UAF the kernel with DMA" is really awful. Jason
