From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shamir Rabinovitch Subject: Re: [PATCH v3] IB/IPoIB: ibX: failed to create mcg debug file Date: Tue, 28 Mar 2017 12:19:41 +0300 Message-ID: <20170328091940.GA14058@srabinov-linux.uk.oracle.com> References: <1490599139-12665-1-git-send-email-shamir.rabinovitch@oracle.com> <20170327195500.GH20443@mtr-leonro.local> <20170327201714.GB29831@srabinov-linux.uk.oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20170327201714.GB29831-t9juWtktDCT52KUv/Ok+f8QLKKaP9WJ9VpNB7YpNyf8@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Leon Romanovsky Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, vijay.ac.kumar-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org List-Id: linux-rdma@vger.kernel.org On Mon, Mar 27, 2017 at 11:17:14PM +0300, Shamir Rabinovitch wrote: > > > > > > > +#ifdef CONFIG_INFINIBAND_IPOIB_DEBUG > > > +static int ipoib_netdev_event(struct notifier_block *this, > > > + unsigned long event, void *ptr) > > > +{ > > > + struct netdev_notifier_info *ni = ptr; > > > + struct net_device *dev = ni->dev; > > > + > > > + if (dev->netdev_ops->ndo_open != ipoib_open) > > > + return NOTIFY_DONE; > > > + > > > + switch (event) { > > > + case NETDEV_REGISTER: > > > + ipoib_create_debug_files(dev); > > > + break; > > > + case NETDEV_CHANGENAME: > > > + ipoib_debugfs_rename(dev); > > > > Why do we need explicit ipoib_debugfs_rename function? > > Will it work by simply calling ipoib_delete_debug_files > > and immediately after that ipoib_create_debug_files? > > > > > > > + break; > > > + case NETDEV_UNREGISTER: > > > + ipoib_delete_debug_files(dev); > > > + break; > > > + } > > > + > > > + return NOTIFY_DONE; > > > +} > > > +#endif > > > + > > Hi Leon, > > Good point. > I will have look on this idea and get back to you. > > BR, Shamir Hi Leon, It seems that the difference between using debugfs_rename and a combination of debugfs_create_file and debugfs_remove is mainly the atomicy of the rename operation with regard to the file system. debugfs_rename is atomic operation while the above combination is not. As result I see kernel panic when the rename operation interleave with the delete due to module unload. So after carefully considering what you suggest I think it might introduce unexpected issues. BR, Shamir -- 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