This is not how RCU works in OVS. Every thread is by default considered active. They rarely quiesce except implicitly inside poll_block(). Please read the large comment at the top of ovs-rcu.h.
Is your patch based on actual bugs that you have found, or is it just some kind of precaution? If it is the latter, then it is not needed. On Tue, Jun 02, 2020 at 11:22:57PM +0000, Yanqin Wei wrote: > Hi Ben, > > If my understanding is correct, the writer could not be a rcu thread because > it does not need report holding or not holding pointers. > So old memory will be freed after all rcu thread report quiesce. > > Best Regards, > Wei Yanqin > > > -----Original Message----- > > From: Ben Pfaff <b...@ovn.org> > > Sent: Wednesday, June 3, 2020 1:28 AM > > To: Linhaifeng <haifeng....@huawei.com> > > Cc: Yanqin Wei <yanqin....@arm.com>; d...@openvswitch.org; nd > > <n...@arm.com>; Lilijun (Jerry) <jerry.lili...@huawei.com>; chenchanghu > > <chenchan...@huawei.com>; Lichunhe <lichu...@huawei.com> > > Subject: Re: [ovs-dev] [PATCH v2] ovs rcu: update rcu pointer first > > > > On Tue, Jun 02, 2020 at 07:27:59AM +0000, Linhaifeng wrote: > > > We should update rcu pointer first then use ovsrcu_postpone to free > > > otherwise maybe cause use-after-free. > > > e.g.,reader indicates momentary quiescent and access old pointer after > > > writer postpone free old pointer and before setting new pointer. > > > > > > Signed-off-by: Linhaifeng <haifeng....@huawei.com> > > > > I don't see how that's possible, since the writer hasn't quiesced. _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev
