From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753128AbaIGXFB (ORCPT ); Sun, 7 Sep 2014 19:05:01 -0400 Received: from mail-pd0-f173.google.com ([209.85.192.173]:58763 "EHLO mail-pd0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752720AbaIGXEN (ORCPT ); Sun, 7 Sep 2014 19:04:13 -0400 From: Tejun Heo To: axboe@kernel.dk Cc: linux-kernel@vger.kernel.org, Tejun Heo Subject: [PATCH 3/6] bdi: remove bdi->wb_lock locking around bdi->dev clearing in bdi_unregister() Date: Mon, 8 Sep 2014 08:03:58 +0900 Message-Id: <1410131041-1881-4-git-send-email-tj@kernel.org> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1410131041-1881-1-git-send-email-tj@kernel.org> References: <1410131041-1881-1-git-send-email-tj@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The only places where NULL test on bdi->dev is used are bdi_[un]register(). The functions can't be called in parallel anyway and there's no point in protecting bdi->dev clearing with a lock. Remove bdi->wb_lock grabbing around bdi->dev clearing and move it after device_unregister() call so that bdi->dev doesn't have to be cached in a local variable. This patch shouldn't introduce any behavior difference. Signed-off-by: Tejun Heo --- mm/backing-dev.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 1706cbb..4afeefe 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -402,21 +402,15 @@ static void bdi_prune_sb(struct backing_dev_info *bdi) void bdi_unregister(struct backing_dev_info *bdi) { - struct device *dev = bdi->dev; - - if (dev) { + if (bdi->dev) { bdi_set_min_ratio(bdi, 0); trace_writeback_bdi_unregister(bdi); bdi_prune_sb(bdi); bdi_wb_shutdown(bdi); bdi_debug_unregister(bdi); - - spin_lock_bh(&bdi->wb_lock); + device_unregister(bdi->dev); bdi->dev = NULL; - spin_unlock_bh(&bdi->wb_lock); - - device_unregister(dev); } } EXPORT_SYMBOL(bdi_unregister); -- 1.9.3