From: Sowmini Varadhan <sowmini.varad...@oracle.com> Date: Tue, 7 Apr 2015 17:56:05 -0400
> On (04/07/15 17:26), David Miller wrote: >> > /* >> > + * we record the send generation after doing the xmit acquire. >> > + * if someone else manages to jump in and do some work, we'll use >> > + * this to avoid a goto restart farther down. >> > + * >> > + * we don't need a lock because the counter is only incremented >> > + * while we have the in_xmit bit held. >> > + */ >> > + conn->c_send_gen++; >> > + send_gen = conn->c_send_gen; >> >> This increment does need to either be changed to be an atomic_t >> or covered by a lock. >> >> Otherwise two concurrent callers can both try to increment it at >> the same time, and it only effectively increments once. That's >> corrupted state and will break all of the new logic added here. > I'm afraid I dont follow what race condiiton you are seeing? Prior > to this line, the "acquire_in_xmit" check would have only allowed > one thread to successfully increment c_send_gen, right? What did I > miss? Then there is locking protecting this counter increment and the comment is wrong. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
