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=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 0A165C282CE for ; Wed, 22 May 2019 19:33:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CF7CA20675 for ; Wed, 22 May 2019 19:33:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558553581; bh=r76SnZdYsqqjxF7jn7OHOjD4pNqn91ObB4C4LK5uPms=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=sNvOXDzxx5C1Zs8RZUCChQEfKGOahKlLZm1bz5hZluiGxJfgwAveBJvGQPJEiwz3g FWNUFhRMZSS01XTdqk3lZNwWOCJ//zoiTbMWlcoP5RRCBoL2ix78jQN3iaqKA76mhU x7m0YJbWTAfLtFswkSC4gwGvR+4cqP0wWu4bJVg8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387728AbfEVTcB (ORCPT ); Wed, 22 May 2019 15:32:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:55606 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387705AbfEVTb7 (ORCPT ); Wed, 22 May 2019 15:31:59 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1950821473; Wed, 22 May 2019 19:31:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558553517; bh=r76SnZdYsqqjxF7jn7OHOjD4pNqn91ObB4C4LK5uPms=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sgLotn9h9ZE2Euws+KkyCXU8PCK7X7ZtwWTjtXJBSFiTARlgOj8ev2p67l6vS5YVi i82MgnsSijQ56cIL4EpiHWqZrwwCJ3JpuAWT/+ttUNmzvGeZ+aJ7xaDMQZxBKp1d7/ WS6xymqNMvTJwzOOqNl9fxZAl29myCjVwfvtoRhs= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Arnd Bergmann , Nathan Chancellor , Coly Li , Jens Axboe , Sasha Levin , linux-bcache@vger.kernel.org Subject: [PATCH AUTOSEL 4.4 21/92] bcache: avoid clang -Wunintialized warning Date: Wed, 22 May 2019 15:30:16 -0400 Message-Id: <20190522193127.27079-21-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190522193127.27079-1-sashal@kernel.org> References: <20190522193127.27079-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Arnd Bergmann [ 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 16c3390e5d9f3..d82ae445c9ee3 100644 --- a/drivers/md/bcache/alloc.c +++ b/drivers/md/bcache/alloc.c @@ -324,10 +324,11 @@ 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