Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030200AbWHZQHb (ORCPT ); Sat, 26 Aug 2006 12:07:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030218AbWHZQHb (ORCPT ); Sat, 26 Aug 2006 12:07:31 -0400 Received: from taganka54-host.corbina.net ([213.234.233.54]:60553 "EHLO screens.ru") by vger.kernel.org with ESMTP id S1030200AbWHZQHa (ORCPT ); Sat, 26 Aug 2006 12:07:30 -0400 Date: Sun, 27 Aug 2006 00:31:42 +0400 From: Oleg Nesterov To: Jens Axboe Cc: Andrew Morton , linux-kernel@vger.kernel.org Subject: [PATCH] exit_io_context: don't disable irqs Message-ID: <20060826203142.GA333@oleg> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1483 Lines: 46 We don't need to disable irqs to clear current->io_context, it is protected by ->alloc_lock. Even IF it was possible to submit I/O from IRQ on behalf of current this irq_disable() can't help: current_io_context() will re-instantiate ->io_context after irq_enable(). We don't need task_lock() or local_irq_disable() to clear ioc->task. This can't prevent other CPUs from playing with our io_context anyway. Signed-off-by: Oleg Nesterov --- 2.6.18-rc4/block/ll_rw_blk.c~6_exit 2006-08-27 00:10:53.000000000 +0400 +++ 2.6.18-rc4/block/ll_rw_blk.c 2006-08-27 00:11:47.000000000 +0400 @@ -3580,25 +3580,22 @@ EXPORT_SYMBOL(put_io_context); /* Called by the exitting task */ void exit_io_context(void) { - unsigned long flags; struct io_context *ioc; struct cfq_io_context *cic; - local_irq_save(flags); task_lock(current); ioc = current->io_context; current->io_context = NULL; - ioc->task = NULL; task_unlock(current); - local_irq_restore(flags); + ioc->task = NULL; if (ioc->aic && ioc->aic->exit) ioc->aic->exit(ioc->aic); if (ioc->cic_root.rb_node != NULL) { cic = rb_entry(rb_first(&ioc->cic_root), struct cfq_io_context, rb_node); cic->exit(ioc); } - + put_io_context(ioc); } - 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/