From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1M3Xdr-0006B8-LM for qemu-devel@nongnu.org; Mon, 11 May 2009 11:42:11 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1M3Xdm-000696-MG for qemu-devel@nongnu.org; Mon, 11 May 2009 11:42:11 -0400 Received: from [199.232.76.173] (port=51101 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1M3Xdm-00068z-IC for qemu-devel@nongnu.org; Mon, 11 May 2009 11:42:06 -0400 Received: from mtaout02-winn.ispmail.ntl.com ([81.103.221.48]:33584) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1M3Xdl-0000Hw-UX for qemu-devel@nongnu.org; Mon, 11 May 2009 11:42:06 -0400 Date: Mon, 11 May 2009 16:42:26 +0100 From: Stuart Brady Subject: Re: [Qemu-devel] [PATCH] suppress 'warn_unused_result' warning Message-ID: <20090511154226.GA29818@miranda.arrow> References: <20090510221500.GA27879@miranda.arrow> <20090510.195335.-1303462317.imp@bsdimp.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090510.195335.-1303462317.imp@bsdimp.com> Reply-To: Stuart Brady List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "M. Warner Losh" Cc: qemu-devel@nongnu.org On Sun, May 10, 2009 at 07:53:35PM -0600, M. Warner Losh wrote: > When a signal is received and you are waiting for data, you get > EINTR. If there's data available, then I believe the behavior is to > return that data and not EINTR. That's the way Unix works. So if I do a read() from a file over NFS, and there's an awful lot of latency (and perhaps even connection problems), and the process gets a signal -- does that mean that the signal will only be delivered once data is returned? If not, then I would really start to wonder whether /all/ code dealing with read(), write(), etc. should be written to cope with EINTR (and also partial reads/writes?) regardless of whatever is done with threads and signal masks, as doing otherwise seems only to be asking for trouble at some point. (I'd be especially concerned about signals intended for libraries that are not under the developer's control...) -- Stuart Brady