From mboxrd@z Thu Jan 1 00:00:00 1970 From: Evgeniy Polyakov Subject: Re: [take23 3/5] kevent: poll/select() notifications. Date: Wed, 8 Nov 2006 20:03:59 +0300 Message-ID: <20061108170358.GA27557@2ka.mipt.ru> References: <11629182482792@2ka.mipt.ru> <20061108084554.GD2447@2ka.mipt.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=koi8-r Cc: David Miller , Ulrich Drepper , Andrew Morton , netdev , Zach Brown , Christoph Hellwig , Chase Venters , Johann Borck , Linux Kernel Mailing List , Jeff Garzik Return-path: Received: from relay.2ka.mipt.ru ([194.85.82.65]:17301 "EHLO 2ka.mipt.ru") by vger.kernel.org with ESMTP id S1753271AbWKHRGL (ORCPT ); Wed, 8 Nov 2006 12:06:11 -0500 To: Davide Libenzi Content-Disposition: inline In-Reply-To: <20061108084554.GD2447@2ka.mipt.ru> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Wed, Nov 08, 2006 at 11:45:54AM +0300, Evgeniy Polyakov (johnpol@2ka.mipt.ru) wrote: > > Are you sure you can safely call file->f_op->poll() from inside a callback > > based wakeup? The low level driver may be calling the wakeup with one of > > its locks held, and during the file->f_op->poll may be trying to acquire > > the same lock. I remember there was a discussion about this, and assuming > > the above not true, made epoll code more complex (and slower, since an > > extra O(R) loop was needed to fetch events). > > Indeed, I have not paid too much attention to poll/select notifications in > kevent actually. As far as I recall it should be called on behalf of process > doing kevent_get_event(). I will check and fix if that is not correct. > Thanks Davide. Indeed there was a bug. Actually poll/select patch was broken quite noticebly - patchset did not include major changes I made for it. I will put them all into next release. Thanks again Davide for pointing that out. -- Evgeniy Polyakov