LWIP_ALLOW_MEM_FREE_FROM_OTHER_CONTEXT macro

Set this to 1 if you want to free PBUF_RAM pbufs (or call mem_free()) from interrupt context (or another context that doesn't allow waiting for a semaphore). If set to 1, mem_malloc will be protected by a semaphore and SYS_ARCH_PROTECT, while mem_free will only use SYS_ARCH_PROTECT. mem_malloc SYS_ARCH_UNPROTECTs with each loop so that mem_free can run. ATTENTION: As you can see from the above description, this leads to dis-/ enabling interrupts often, which can be slow! Also, on low memory, mem_malloc can need longer. If you don't want that, at least for NO_SYS=0, you can still use the following functions to enqueue a deallocation call which then runs in the tcpip_thread context: - pbuf_free_callback(p); - mem_free_callback(m);