From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f72.google.com (mail-pa0-f72.google.com [209.85.220.72]) by kanga.kvack.org (Postfix) with ESMTP id A658D6B0253 for ; Thu, 13 Oct 2016 12:51:23 -0400 (EDT) Received: by mail-pa0-f72.google.com with SMTP id fn2so84170070pad.7 for ; Thu, 13 Oct 2016 09:51:23 -0700 (PDT) Received: from mail-pf0-x241.google.com (mail-pf0-x241.google.com. [2607:f8b0:400e:c00::241]) by mx.google.com with ESMTPS id uj2si12680644pab.206.2016.10.13.09.50.56 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 13 Oct 2016 09:50:56 -0700 (PDT) Received: by mail-pf0-x241.google.com with SMTP id 128so5434521pfz.1 for ; Thu, 13 Oct 2016 09:50:56 -0700 (PDT) Date: Thu, 13 Oct 2016 18:50:49 +0200 From: Vitaly Wool Subject: [PATCH 2/3] z3fold: remove redundant locking Message-Id: <20161013185049.adaf153cc8bb1eb1408702f5@gmail.com> In-Reply-To: <20161013184758.9ecfd318fa542e14e2d2c5b1@gmail.com> References: <20161013184758.9ecfd318fa542e14e2d2c5b1@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Linux-MM , linux-kernel@vger.kernel.org Cc: Dan Streetman , Andrew Morton , Dave Chinner 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org