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Fri, 25 Sep 2020 02:40:53 +0000 (UTC) X-HE-Tag: wax24_4f0fb2627164 X-Filterd-Recvd-Size: 4188 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf02.hostedemail.com (Postfix) with ESMTP for ; Fri, 25 Sep 2020 02:40:53 +0000 (UTC) Received: from X1 (unknown [104.245.68.101]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 64FD520809; Fri, 25 Sep 2020 02:40:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601001652; bh=pQ6z0ir2xfCPVTr5SFHMaCkXwYdTbS6aBAi6ME84jmI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=anFlFAk26hM03/gZSTtDSTWfEbCDm6NCgWWmhIiYHOzGjLoYA71QVZq0sNyqzMUgo 9Zwufj2fRF4UjFOig14Yciftyjvpqbm9AfNqHcLBcSsdZI5YvqVK0fZieuRPqd2G7+ NBEQCrN9tudI1Az3ILeOCBk+fvWrZe47aa+iS/hs= Date: Thu, 24 Sep 2020 19:40:51 -0700 From: Andrew Morton To: Miaohe Lin Cc: , Subject: Re: [PATCH v2] mm/mempool: Add 'else' to split mutually exclusive case Message-Id: <20200924194051.6b1aa0470114d90c6ef665af@linux-foundation.org> In-Reply-To: <20200924111641.28922-1-linmiaohe@huawei.com> References: <20200924111641.28922-1-linmiaohe@huawei.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000222, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, 24 Sep 2020 07:16:41 -0400 Miaohe Lin wrote: > Add else to split mutually exclusive case and avoid some unnecessary check. > It doesn't seem to change code generation (compiler is smart), but I think > it helps readability. > > ... > > --- a/mm/mempool.c > +++ b/mm/mempool.c > @@ -58,11 +58,10 @@ static void __check_element(mempool_t *pool, void *element, size_t size) > static void check_element(mempool_t *pool, void *element) > { > /* Mempools backed by slab allocator */ > - if (pool->free == mempool_free_slab || pool->free == mempool_kfree) > + if (pool->free == mempool_free_slab || pool->free == mempool_kfree) { > __check_element(pool, element, ksize(element)); > - > /* Mempools backed by page allocator */ > - if (pool->free == mempool_free_pages) { > + } else if (pool->free == mempool_free_pages) { > int order = (int)(long)pool->pool_data; > void *addr = kmap_atomic((struct page *)element); > > @@ -82,11 +81,10 @@ static void __poison_element(void *element, size_t size) > static void poison_element(mempool_t *pool, void *element) > { > /* Mempools backed by slab allocator */ > - if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc) > + if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc) { > __poison_element(element, ksize(element)); > - > /* Mempools backed by page allocator */ > - if (pool->alloc == mempool_alloc_pages) { > + } else if (pool->alloc == mempool_alloc_pages) { > int order = (int)(long)pool->pool_data; > void *addr = kmap_atomic((struct page *)element); > OK, I guess. But the comments are now in the wrong place. --- a/mm/mempool.c~mm-mempool-add-else-to-split-mutually-exclusive-case-fix +++ a/mm/mempool.c @@ -60,8 +60,8 @@ static void check_element(mempool_t *poo /* Mempools backed by slab allocator */ if (pool->free == mempool_free_slab || pool->free == mempool_kfree) { __check_element(pool, element, ksize(element)); - /* Mempools backed by page allocator */ } else if (pool->free == mempool_free_pages) { + /* Mempools backed by page allocator */ int order = (int)(long)pool->pool_data; void *addr = kmap_atomic((struct page *)element); @@ -83,8 +83,8 @@ static void poison_element(mempool_t *po /* Mempools backed by slab allocator */ if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc) { __poison_element(element, ksize(element)); - /* Mempools backed by page allocator */ } else if (pool->alloc == mempool_alloc_pages) { + /* Mempools backed by page allocator */ int order = (int)(long)pool->pool_data; void *addr = kmap_atomic((struct page *)element); _