Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753685AbXFWL5X (ORCPT ); Sat, 23 Jun 2007 07:57:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750837AbXFWL5Q (ORCPT ); Sat, 23 Jun 2007 07:57:16 -0400 Received: from nic.NetDirect.CA ([216.16.235.2]:33939 "EHLO rubicon.netdirect.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750833AbXFWL5P (ORCPT ); Sat, 23 Jun 2007 07:57:15 -0400 X-Originating-Ip: 72.143.66.27 Date: Sat, 23 Jun 2007 07:52:51 -0400 (EDT) From: "Robert P. J. Day" X-X-Sender: rpjday@localhost.localdomain To: Arnd Bergmann cc: Florin Iucha , Linux Kernel Mailing List Subject: Re: "upping" a semaphore from interrupt context? In-Reply-To: <200706221934.18436.arnd@arndb.de> Message-ID: References: <20070622173839.GB8398@iucha.net> <200706221934.18436.arnd@arndb.de> MIME-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="8323328-343429529-1182599571=:4164" X-Net-Direct-Inc-MailScanner-Information: Please contact the ISP for more information X-Net-Direct-Inc-MailScanner: Found to be clean X-Net-Direct-Inc-MailScanner-SpamCheck: not spam, SpamAssassin (not cached, score=-16.8, required 5, autolearn=not spam, ALL_TRUSTED -1.80, BAYES_00 -15.00, INIT_RECVD_OUR_AUTH -20.00, RCVD_IN_SORBS_DUL 20.00) X-Net-Direct-Inc-MailScanner-From: rpjday@mindspring.com Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1547 Lines: 39 This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323328-343429529-1182599571=:4164 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT On Fri, 22 Jun 2007, Arnd Bergmann wrote: > On Friday 22 June 2007, Florin Iucha wrote: > > I am writing a USB driver for some custom hardware, and I need to > > synchronize between the user-space and the USB subsystem. ?Can I > > create a semaphore and "down" it in the reader then "up" it in the > > completion handler? > > yes, but you should not. The use of semaphores is not recommended > for new code, it should be replaced with either a mutex or a > completion. can you clarify this? it sounds like you're saying that the current implementation of semaphores is entirely superfluous. but surely it isn't possible to replace all semaphores with either mutexes or completions, is it? rday -- ======================================================================== Robert P. J. Day Linux Consulting, Training and Annoying Kernel Pedantry Waterloo, Ontario, CANADA http://fsdev.net/wiki/index.php?title=Main_Page ======================================================================== --8323328-343429529-1182599571=:4164-- - 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/