On Tue, Aug 1, 2017 at 8:20 AM, maowenan <maowe...@huawei.com> wrote: > > + /* If needed, reset TLP/RTO timer; RACK may later override this. */ > [Mao Wenan] I have question about RACK, if there is no RACK feature > in lower version, who can clear this flag:FLAG_SET_XMIT_TIMER?
In the comment, "this" is referring to the xmit timer. The comment is referring to the fact that RACK (or similarly tcp_pause_early_retransmit() in earlier kernels) can override the value of the xmit timer set in tcp_set_xmit_timer(). The comment is not claiming that RACK clears the FLAG_SET_XMIT_TIMER bit in "flag". Note that "flag" is an argument to tcp_ack(). And while processing a given incoming ACK, the callers of tcp_ack() pass in either 0 or one or more constant bit flags. So FLAG_SET_XMIT_TIMER and all the other bit flags are implicitly set to zero at the beginning of processing each ACK. neal
