From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,T_DKIMWL_WL_HIGH,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D33BDC28CC1 for ; Thu, 30 May 2019 03:20:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ACC6E24972 for ; Thu, 30 May 2019 03:20:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559186446; bh=tZflS49DPNtO7Lc38JLA01S4YHi42nusf2afGwu/Y7Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=UC87N2DsvQ4bdezRjEhG+9Cd3c7UCYI6O3RAIy0G+ax5+iYvv83umsvPRH3YWucR+ OQmpA4OTnk1n/RiMgePvGMYVGg1BZuFb15nWRyhB5fvoBWeMVuBEQrv2kSNB4ln9CO Rt6Pj5Mgp1sp93dzjqUznqWB2kF2oj/yLtIQRvHE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731111AbfE3DUp (ORCPT ); Wed, 29 May 2019 23:20:45 -0400 Received: from mail.kernel.org ([198.145.29.99]:59750 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732312AbfE3DUo (ORCPT ); Wed, 29 May 2019 23:20:44 -0400 Received: from localhost (ip67-88-213-2.z213-88-67.customer.algx.net [67.88.213.2]) (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 1E9C524934; Thu, 30 May 2019 03:20:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559186444; bh=tZflS49DPNtO7Lc38JLA01S4YHi42nusf2afGwu/Y7Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=z38nWaLz4LH60RyyDxLeMkFQcv/sER9h34wnpjCYDXkAfJunR9fZtlqw/hscNcuIm mv3tgzecGGgLSwo0PCxQWeSP9yTldaoQfuV+2qn39wr9avw9Cl3IUwGFH/DwitH+eN 3FFBN8lBao6NqJ0Gp5tIvii95nkFd2Bpv0qMyY8M= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Arnd Bergmann , Nathan Chancellor , Coly Li , Jens Axboe , Sasha Levin Subject: [PATCH 4.9 049/128] bcache: avoid clang -Wunintialized warning Date: Wed, 29 May 2019 20:06:21 -0700 Message-Id: <20190530030443.598433870@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190530030432.977908967@linuxfoundation.org> References: <20190530030432.977908967@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org [ Upstream commit 78d4eb8ad9e1d413449d1b7a060f50b6efa81ebd ] clang has identified a code path in which it thinks a variable may be unused: drivers/md/bcache/alloc.c:333:4: error: variable 'bucket' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized] fifo_pop(&ca->free_inc, bucket); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ drivers/md/bcache/util.h:219:27: note: expanded from macro 'fifo_pop' #define fifo_pop(fifo, i) fifo_pop_front(fifo, (i)) ^~~~~~~~~~~~~~~~~~~~~~~~~ drivers/md/bcache/util.h:189:6: note: expanded from macro 'fifo_pop_front' if (_r) { \ ^~ drivers/md/bcache/alloc.c:343:46: note: uninitialized use occurs here allocator_wait(ca, bch_allocator_push(ca, bucket)); ^~~~~~ drivers/md/bcache/alloc.c:287:7: note: expanded from macro 'allocator_wait' if (cond) \ ^~~~ drivers/md/bcache/alloc.c:333:4: note: remove the 'if' if its condition is always true fifo_pop(&ca->free_inc, bucket); ^ drivers/md/bcache/util.h:219:27: note: expanded from macro 'fifo_pop' #define fifo_pop(fifo, i) fifo_pop_front(fifo, (i)) ^ drivers/md/bcache/util.h:189:2: note: expanded from macro 'fifo_pop_front' if (_r) { \ ^ drivers/md/bcache/alloc.c:331:15: note: initialize the variable 'bucket' to silence this warning long bucket; ^ This cannot happen in practice because we only enter the loop if there is at least one element in the list. Slightly rearranging the code makes this clearer to both the reader and the compiler, which avoids the warning. Signed-off-by: Arnd Bergmann Reviewed-by: Nathan Chancellor Signed-off-by: Coly Li Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- drivers/md/bcache/alloc.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/md/bcache/alloc.c b/drivers/md/bcache/alloc.c index dd344ee9e62b7..ebacd21714efa 100644 --- a/drivers/md/bcache/alloc.c +++ b/drivers/md/bcache/alloc.c @@ -322,10 +322,11 @@ static int bch_allocator_thread(void *arg) * possibly issue discards to them, then we add the bucket to * the free list: */ - while (!fifo_empty(&ca->free_inc)) { + while (1) { long bucket; - fifo_pop(&ca->free_inc, bucket); + if (!fifo_pop(&ca->free_inc, bucket)) + break; if (ca->discard) { mutex_unlock(&ca->set->bucket_lock); -- 2.20.1