From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754081AbcJOMPQ (ORCPT ); Sat, 15 Oct 2016 08:15:16 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:35302 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752096AbcJOMPH (ORCPT ); Sat, 15 Oct 2016 08:15:07 -0400 Date: Sat, 15 Oct 2016 13:59:47 +0200 From: Vitaly Wool To: Vitaly Wool Cc: Linux-MM , linux-kernel@vger.kernel.org, Dan Streetman , Andrew Morton , Dave Chinner Subject: [PATCH v5 2/3] z3fold: remove redundant locking Message-Id: <20161015135947.5adf02bae01986ea8b79edd9@gmail.com> In-Reply-To: <20161015135632.541010b55bec496e2cae056e@gmail.com> References: <20161015135632.541010b55bec496e2cae056e@gmail.com> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The per-pool z3fold spinlock should generally be taken only when a non-atomic pool variable is modified. There's no need to take it to map/unmap an object. Signed-off-by: Vitaly Wool --- mm/z3fold.c | 17 +++++------------ 1 file changed, 5 insertions(+), 12 deletions(-) diff --git a/mm/z3fold.c b/mm/z3fold.c index 5197d7b..10513b5 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -580,6 +580,7 @@ next: if ((test_bit(PAGE_HEADLESS, &page->private) && ret == 0) || (zhdr->first_chunks == 0 && zhdr->last_chunks == 0 && zhdr->middle_chunks == 0)) { + spin_unlock(&pool->lock); /* * All buddies are now free, free the z3fold page and * return success. @@ -587,7 +588,6 @@ next: clear_bit(PAGE_HEADLESS, &page->private); free_z3fold_page(zhdr); atomic64_dec(&pool->pages_nr); - spin_unlock(&pool->lock); return 0; } else if (!test_bit(PAGE_HEADLESS, &page->private)) { if (zhdr->first_chunks != 0 && @@ -629,7 +629,6 @@ static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle) void *addr; enum buddy buddy; - spin_lock(&pool->lock); zhdr = handle_to_z3fold_header(handle); addr = zhdr; page = virt_to_page(zhdr); @@ -656,7 +655,6 @@ static void *z3fold_map(struct z3fold_pool *pool, unsigned long handle) break; } out: - spin_unlock(&pool->lock); return addr; } @@ -671,19 +669,14 @@ static void z3fold_unmap(struct z3fold_pool *pool, unsigned long handle) struct page *page; enum buddy buddy; - spin_lock(&pool->lock); zhdr = handle_to_z3fold_header(handle); page = virt_to_page(zhdr); - if (test_bit(PAGE_HEADLESS, &page->private)) { - spin_unlock(&pool->lock); - return; + if (!test_bit(PAGE_HEADLESS, &page->private)) { + buddy = handle_to_buddy(handle); + if (buddy == MIDDLE) + clear_bit(MIDDLE_CHUNK_MAPPED, &page->private); } - - buddy = handle_to_buddy(handle); - if (buddy == MIDDLE) - clear_bit(MIDDLE_CHUNK_MAPPED, &page->private); - spin_unlock(&pool->lock); } /** -- 2.4.2