Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 13 Oct 2002 15:34:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 13 Oct 2002 15:34:21 -0400 Received: from svr-ganmtc-appserv-mgmt.ncf.coxexpress.com ([24.136.46.5]:54792 "EHLO svr-ganmtc-appserv-mgmt.ncf.coxexpress.com") by vger.kernel.org with ESMTP id ; Sun, 13 Oct 2002 15:34:20 -0400 Subject: Re: in_atomic() & spin_lock / spin_unlock in different functions From: Robert Love To: Pavel Machek Cc: kernel list In-Reply-To: <20021013203838.A122@elf.ucw.cz> References: <20021013203838.A122@elf.ucw.cz> Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Mailer: Ximian Evolution 1.0.8 (1.0.8-10) Date: 13 Oct 2002 15:40:09 -0400 Message-Id: <1034538009.753.4507.camel@phantasy> Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1018 Lines: 31 On Sun, 2002-10-13 at 14:38, Pavel Machek wrote: > I'm doing spin_lock_irqsave() then in another function > spin_unlock_irqrestore. Is that okay? If no, can it cause "scheduling > in atomic"? It is not OK if the function is run by a different process. Then one process will have a preempt_count one larger than it should and one would have a preempt_count one smaller. The task with the one smaller preempt_count will probably cause a crash when it preemptively reschedules erroneously. In other words, you have: Process A Process B preempt_count++ preempt_count-- When both of those routines need to be done by the same process. Also, you cannot use spin_lock_irqsave() in different functions at all on sparc as it contains stack information. Robert Love - 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/