Re: [lwip-users] critical section protection + timer issues questions

[Scott Taggart]

One additional question regarding critical code sections and LWIP.  I don’t understand how LWIP is protecting itself from incoming frames.  Presumably, incoming frames (say on an EN interface) arrive in at interrupt time/context and end up calling ip_input and then tcp_input.  tcp_input (as just one example) manipulates the pcb lists w/o protection.  Suppose a another thread happens to also be manipulating a pcb list when an inbound EN frame arrives?  Is LWIP assuming that all inbound frames will be processed by a polling model?  Even then, the thread that polls is not guaranteed to run to completion before another thread runs (e.g., the polling input thread could be interrupted by another thread for vice-versa).

Can someone explain the inbound packet path protection mechanism to me?

Thanks,

Scott