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[94.113.223.73]) by smtp.gmail.com with ESMTPSA id o15sm20167010wrj.59.2019.03.27.03.43.19 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 27 Mar 2019 03:43:19 -0700 (PDT) Date: Wed, 27 Mar 2019 11:43:19 +0100 From: Jiri Pirko To: Michal Kubecek Cc: David Miller , netdev@vger.kernel.org, Jakub Kicinski , Andrew Lunn , Florian Fainelli , John Linville , Stephen Hemminger , linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next v5 08/22] ethtool: support for netlink notifications Message-ID: <20190327104319.GG6979@nanopsycho> References: <3578e5f334acf11b84e75d0ee41c072340a7b085.1553532199.git.mkubecek@suse.cz> <20190326163400.GC4958@nanopsycho.orion> <20190326181720.GO26076@unicorn.suse.cz> <20190327093843.GB6979@nanopsycho> <20190327095950.GQ26076@unicorn.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190327095950.GQ26076@unicorn.suse.cz> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Wed, Mar 27, 2019 at 10:59:50AM CET, mkubecek@suse.cz wrote: >On Wed, Mar 27, 2019 at 10:38:43AM +0100, Jiri Pirko wrote: >> Tue, Mar 26, 2019 at 07:17:20PM CET, mkubecek@suse.cz wrote: >> >On Tue, Mar 26, 2019 at 05:34:00PM +0100, Jiri Pirko wrote: >> >> Mon, Mar 25, 2019 at 06:08:18PM CET, mkubecek@suse.cz wrote: >> >> >+void ethtool_notify(struct net_device *dev, struct netlink_ext_ack *extack, >> >> >+ unsigned int cmd, u32 req_mask, const void *data) >> >> >+{ >> >> >+ if (unlikely(!ethnl_ok)) >> >> >> >> Why do you need this? >> > >> >If genetlink family registration fails, ethtool_notify() can be still >> >called from other code (e.g. the ethtool ioctl interface). In such case, >> >better bail out right away than fail somewhere later (probably after >> >preparing the message which can't be sent anyway). >> >> Again, haven't seen this in any other gen netlink implementation. Why do >> they not need it? > >Do they have notifications triggered from other code by directly calling >a function (i.e. not through e.g. a netdev notifier)? Okay, got it. > >An alternative to a flag would be using a RCU pointer for this function >(initialized to null and set once the family is registered) which is >what e.g. netfilter is doing with its hooks but that would mean that >each external notification would use an indirect call. It's slow path, I don't think this kind of overhead is of any issue. Sounds good. > >> >> >diff --git a/net/ethtool/netlink.h b/net/ethtool/netlink.h >> >> >index b8a6cd3dc3e3..5f2299548915 100644 >> >> >--- a/net/ethtool/netlink.h >> >> >+++ b/net/ethtool/netlink.h >> >> >@@ -11,6 +11,8 @@ >> >> > #define ETHNL_SET_ERRMSG(info, msg) \ >> >> > do { if (info) GENL_SET_ERR_MSG(info, msg); } while (0) >> >> > >> >> >+extern u32 ethnl_bcast_seq; >> >> >> >> Why do you need to have this in header? Second, it is not used by >> >> anything. Please don't introduce variables that are not used. Introduce >> >> them only in patch where you use it. >> > >> >It's the same as with ethtool_genl_family. I'll make it static as well >> >until it's used in some other file. >> >> Not only static. You should remove it as you are not using it in this >> patch at all. > >OK > >Michal