From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver.Neukum@lrz.uni-muenchen.de Date: Wed, 13 Nov 2002 14:15:01 +0000 Subject: Re: hotplug (was devfs) Message-Id: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-hotplug@vger.kernel.org On Wed, 13 Nov 2002, Nick Craig-Wood wrote: > On Tue, Nov 12, 2002 at 01:51:08PM +0100, Oliver Neukum wrote: > > > Actually, here's a question: are /sbin/hotplug upcalls serialized in > > > some fashion? I'd hate to online a thousand devices in my disk array > > > and have the machine forkbomb itself. > > > > Nope, no serialisation. You don't have any guarantee even that > > addition will be delivered before removal. > > And that is why (we finally discovered) we were getting > non-deterministic device numbering of USB nodes. > > We have machines with 6 x 4 port USB <-> serial converters attached. > These would get randomly assigned usb device ids and hence random > /dev/ttyUSB nodes. Not very useful when there is a load of different > things attached to the 24 serial ports! Please clarify. Did this happen if you connected a hub these gadgets sit on? Do you use the same type of device six times ? > Sometimes we also found that one of the devices wouldn't get > initialised properly. > > We fixed these problems by removing hotplug and loading the relevant > kernel modules in the correct order and voila a perfectly Modules ? Plural? > deterministic order for the /dev/ttyUSBs with all devices initialised. > Plugging in our USB bus with 24 devices on it does indeed produce a > mini-forkbomb effect ;-) (Especially since these Keyspan devices are > initialised twice - once without firmware and once with firmware.) There's a further problem. > So - perhaps hotplug ought to be serialised? Definitely, but how far? Regards Oliver ------------------------------------------------------- This sf.net email is sponsored by: Are you worried about your web server security? Click here for a FREE Thawte Apache SSL Guide and answer your Apache SSL security needs: http://www.gothawte.com/rd523.html _______________________________________________ Linux-hotplug-devel mailing list http://linux-hotplug.sourceforge.net Linux-hotplug-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-hotplug-devel