Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754871AbXABPrL (ORCPT ); Tue, 2 Jan 2007 10:47:11 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755326AbXABPrK (ORCPT ); Tue, 2 Jan 2007 10:47:10 -0500 Received: from iolanthe.rowland.org ([192.131.102.54]:40942 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754871AbXABPrJ (ORCPT ); Tue, 2 Jan 2007 10:47:09 -0500 Date: Tue, 2 Jan 2007 10:47:08 -0500 (EST) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Oliver Neukum cc: Oliver Neukum , , , Subject: Re: error handling in sysfs, fill_read_buffer() In-Reply-To: <200701021638.49726.oliver@neukum.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1749 Lines: 48 On Tue, 2 Jan 2007, Oliver Neukum wrote: > Am Dienstag, 2. Januar 2007 16:26 schrieb Alan Stern: > > On Tue, 2 Jan 2007, Oliver Neukum wrote: > > > > > Hi, > > > > > > if a driver returns an error in fill_read_buffer(), the buffer will be > > > marked as filled. Subsequent reads will return eof. But there is > > > no data because of an error, not because it has been read. > > > Not marking the buffer filled is the obvious fix. > > > > > > Regards > > > Oliver > > > > > > Signed-off-by: Oliver Neukum > > > -- > > > > > > --- a/fs/sysfs/file.c 2006-12-24 05:00:32.000000000 +0100 > > > +++ b/fs/sysfs/file.c 2007-01-01 15:03:14.000000000 +0100 > > > @@ -70,7 +70,8 @@ > > > * Allocate @buffer->page, if it hasn't been already, then call the > > > * kobject's show() method to fill the buffer with this attribute's > > > * data. > > > - * This is called only once, on the file's first read. > > > + * This is called only once, on the file's first read unless an error > > > + * is returned. > > > */ > > > > I don't think this matches what people expect of sysfs. If a show method > > fails then the assumption is that the file cannot be read at all, so > > there's no point in trying to call the method again. > > This would make handling ENOMEM very hard. No harder than handling any other error: Close the sysfs file, then open it and try to read it again. On the other hand, I agree there's nothing substantively wrong with the patch. Alan Stern - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/