From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Gunthorpe Subject: Re: Netlink messages without NLM_F_REQUEST flag Date: Wed, 7 Jun 2017 10:47:50 -0600 Message-ID: <20170607164750.GA7507@obsidianresearch.com> References: <20170607161901.GD1127@mtr-leonro.local> <20170607163758.GA25313@obsidianresearch.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Leon Romanovsky Cc: Kaike Wan , John Fleck , Ira Weiny , Thomas Graf , Doug Ledford , Jiri Pirko , RDMA mailing list , linux-netdev List-Id: linux-rdma@vger.kernel.org On Wed, Jun 07, 2017 at 07:43:44PM +0300, Leon Romanovsky wrote: > On Wed, Jun 7, 2017 at 7:37 PM, Jason Gunthorpe > wrote: > > On Wed, Jun 07, 2017 at 07:19:01PM +0300, Leon Romanovsky wrote: > >> It makes me wonder if it is expected behavior for > >> ibnl_rcv_reply_skb() to handle !NLM_F_REQUEST messages and do we > >> really need it? What are the scenarios? In my use case, which is > >> for sure different from yours, I'm always setting NLM_F_REQUEST > >> while communicating with kernel. > > > > If I recall the user space SA code issues REQUESTS from the kernel to > > userspace, so userspace returns with the response format. This is > > abnormal for netlink hence the special function. > > In netlink semantics, kernel side is supposed to send netlink > notification message and userspace is supposed to send REQUEST. That pattern is for async communications, the SA stuff needs a sync protocol, unfortunately. Jason -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html