Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752762Ab0GYLaE (ORCPT ); Sun, 25 Jul 2010 07:30:04 -0400 Received: from smtp.nokia.com ([192.100.105.134]:43499 "EHLO mgw-mx09.nokia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752676Ab0GYL3g (ORCPT ); Sun, 25 Jul 2010 07:29:36 -0400 From: Artem Bityutskiy To: Jens Axboe Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCHv6 15/15] writeback: cleanup bdi_register Date: Sun, 25 Jul 2010 14:29:25 +0300 Message-Id: <1280057365-10297-16-git-send-email-dedekind1@gmail.com> X-Mailer: git-send-email 1.7.1.1 In-Reply-To: <1280057365-10297-1-git-send-email-dedekind1@gmail.com> References: <1280057365-10297-1-git-send-email-dedekind1@gmail.com> X-OriginalArrivalTime: 25 Jul 2010 11:29:30.0532 (UTC) FILETIME=[A5DEF640:01CB2BEC] X-Nokia-AV: Clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2709 Lines: 92 From: Artem Bityutskiy This patch makes sure we first initialize everything and set the BDI_registered flag, and only after this we add the bdi to 'bdi_list'. Current code adds the bdi to the list too early, and as a result I the WARN(!test_bit(BDI_registered, &bdi->state) in bdi forker is triggered. Also, it is in general good practice to make things visible only when they are fully initialized. Also, this patch does few micro clean-ups: 1. Removes the 'exit' label which does not do anything, just returns. This allows to get rid of few braces and 'ret' variable and make the code smaller. 2. If 'kthread_run()' fails, remove the error code it returns, not hard-coded '-ENOMEM'. Theoretically, some day 'kthread_run()' can return something else. Also, in case of failure it is not necessary to set 'bdi->wb.task' to NULL. Signed-off-by: Artem Bityutskiy --- mm/backing-dev.c | 30 +++++++++++------------------- 1 files changed, 11 insertions(+), 19 deletions(-) diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 9008c4e..0b8ee66 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -511,23 +511,16 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent, const char *fmt, ...) { va_list args; - int ret = 0; struct device *dev; if (bdi->dev) /* The driver needs to use separate queues per device */ - goto exit; + return 0; va_start(args, fmt); dev = device_create_vargs(bdi_class, parent, MKDEV(0, 0), bdi, fmt, args); va_end(args); - if (IS_ERR(dev)) { - ret = PTR_ERR(dev); - goto exit; - } - - spin_lock_bh(&bdi_lock); - list_add_tail_rcu(&bdi->bdi_list, &bdi_list); - spin_unlock_bh(&bdi_lock); + if (IS_ERR(dev)) + return PTR_ERR(dev); bdi->dev = dev; @@ -541,20 +534,19 @@ int bdi_register(struct backing_dev_info *bdi, struct device *parent, wb->task = kthread_run(bdi_forker_thread, wb, "bdi-%s", dev_name(dev)); - if (IS_ERR(wb->task)) { - wb->task = NULL; - ret = -ENOMEM; - - bdi_remove_from_list(bdi); - goto exit; - } + if (IS_ERR(wb->task)) + return PTR_ERR(wb->task); } bdi_debug_register(bdi, dev_name(dev)); set_bit(BDI_registered, &bdi->state); + + spin_lock_bh(&bdi_lock); + list_add_tail_rcu(&bdi->bdi_list, &bdi_list); + spin_unlock_bh(&bdi_lock); + trace_writeback_bdi_register(bdi); -exit: - return ret; + return 0; } EXPORT_SYMBOL(bdi_register); -- 1.7.1.1 -- 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/