On 13-01-17 08:24 AM, Stanislav Kinsbursky wrote: .. > This looks like the old issue I was trying to fix with "SUNRPC: protect service sockets lists during > per-net shutdown". > So, here is the problem as I see it: there is a transport, which is processed by service thread and > it's processing is racing with per-net service shutdown: > > CPU#0: CPU#1: > > svc_recv svc_close_net > svc_get_next_xprt (list_del_init(xpt_ready)) > svc_close_list (set XPT_BUSY and XPT_CLOSE) > svc_clear_pools(xprt was gained on CPU#0 already) > svc_delete_xprt (set XPT_DEAD) > svc_handle_xprt (is XPT_CLOSE => svc_delete_xprt() > BUG() > > So, from my POW, we need some way to: > 1) Skip such in-progress transports on svc_close_net() call (there is not way to detect them, or at > least I don't see one) > 2) Delete the transport after somewhere after svc_xprt_received() > > But there is a problem with svc_xprt_received(): there is a call for svc_xprt_put() in it > (svc_recv->svc_handle_xprt->svc_xprt_received->svc_xprt_put) . And if we are the only user - then > the transport will be destroyed. But transport is dereferenced later in svc_recv() after the > svc_handle_xprt call. Sounds like a reference count type of problem/solution (kref) (?) -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
