Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756312AbaGQJhY (ORCPT ); Thu, 17 Jul 2014 05:37:24 -0400 Received: from mail-wi0-f173.google.com ([209.85.212.173]:44436 "EHLO mail-wi0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755432AbaGQJhV (ORCPT ); Thu, 17 Jul 2014 05:37:21 -0400 Message-ID: <53C79949.7010201@gmail.com> Date: Thu, 17 Jul 2014 12:37:13 +0300 From: Boaz Harrosh User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Paul Bolle , Christoph Hellwig , viro@zeniv.linux.org.uk CC: Borislav Petkov , Sam Ravnborg , pramod.gurav.etc@gmail.com, Jason Cooper , Markus Mayer , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: direct-io: squelch maybe-uninitialized warning in do_direct_IO() References: <1404452632-10912-1-git-send-email-pramod.gurav.etc@gmail.com> <20140713115022.GA6054@infradead.org> <53C6B199.2070606@gmail.com> <20140716175803.GA3631@infradead.org> <1405536124.4357.17.camel@x41> In-Reply-To: <1405536124.4357.17.camel@x41> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Paul Bolle The following warnings: fs/direct-io.c: In function ‘__blockdev_direct_IO’: fs/direct-io.c:1011:12: warning: ‘to’ may be used uninitialized in this function [-Wmaybe-uninitialized] fs/direct-io.c:913:16: note: ‘to’ was declared here fs/direct-io.c:1011:12: warning: ‘from’ may be used uninitialized in this function [-Wmaybe-uninitialized] fs/direct-io.c:913:10: note: ‘from’ was declared here are false positive because dio_get_page() either fails, or sets both 'from' and 'to'. Maybe it's better to move initializing "to" and "from" out of dio_get_page(). That _might_ make it easier for both the the reader and the compiler to understand what's going on. Something like this: Christoph Hellwig said ... The fix of moving the code defintively looks nicer, while I think uninitialized_var is horrible wart that won't get anywhere near my code. Boaz Harrosh I agree with Christoph and Paul Signed-off-by: Paul Bolle Signed-off-by: Boaz Harrosh --- fs/direct-io.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/fs/direct-io.c b/fs/direct-io.c index 98040ba..2f024fc 100644 --- a/fs/direct-io.c +++ b/fs/direct-io.c @@ -198,9 +198,8 @@ static inline int dio_refill_pages(struct dio *dio, struct dio_submit *sdio) * L1 cache. */ static inline struct page *dio_get_page(struct dio *dio, - struct dio_submit *sdio, size_t *from, size_t *to) + struct dio_submit *sdio) { - int n; if (dio_pages_present(sdio) == 0) { int ret; @@ -209,10 +208,7 @@ static inline struct page *dio_get_page(struct dio *dio, return ERR_PTR(ret); BUG_ON(dio_pages_present(sdio) == 0); } - n = sdio->head++; - *from = n ? 0 : sdio->from; - *to = (n == sdio->tail - 1) ? sdio->to : PAGE_SIZE; - return dio->pages[n]; + return dio->pages[sdio->head]; } /** @@ -911,11 +907,15 @@ static int do_direct_IO(struct dio *dio, struct dio_submit *sdio, while (sdio->block_in_file < sdio->final_block_in_request) { struct page *page; size_t from, to; - page = dio_get_page(dio, sdio, &from, &to); + + page = dio_get_page(dio, sdio); if (IS_ERR(page)) { ret = PTR_ERR(page); goto out; } + from = sdio->head ? 0 : sdio->from; + to = (sdio->head == sdio->tail - 1) ? sdio->to : PAGE_SIZE; + sdio->head++; while (from < to) { unsigned this_chunk_bytes; /* # of bytes mapped */ -- 1.9.3 -- 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/