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=unavailable 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 77BCFC282CE for ; Wed, 22 May 2019 19:38:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4789B20675 for ; Wed, 22 May 2019 19:38:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558553925; bh=DhmiDpaApVO07Y6QTOeqICdGFhTwm3yFOL1mbaF/OIs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=GcUWvI9vakwKXIdcOEruwmqQ3D+hcviHJa+qDh5169zqCtVcH/X8PxGGmjREHYRvH mlDQkfknKOP4cAeM8Nq/BJZeOQJzLmWbhxmx3dVT0Yy4jps/M0UlcEWyN5fusOVlhf /CsksaW17O1zkM/0T5lrSxfZPQVrmjJdwGaSoZEM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731751AbfEVTij (ORCPT ); Wed, 22 May 2019 15:38:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:53022 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733039AbfEVT3u (ORCPT ); Wed, 22 May 2019 15:29:50 -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 6EAA221473; Wed, 22 May 2019 19:29:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1558553389; bh=DhmiDpaApVO07Y6QTOeqICdGFhTwm3yFOL1mbaF/OIs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=j5IRKbYM+k9djYp4aLrsKqsdux6Y8XS7RXqdV/xkP6SG7aYTk99cQe8iyDftF9MiZ ZIYBfBSFJfR7IJNJXHLMUIDTN0j5ONUrTcwah1kBuOsyOF6w8eIgjk/fnhOnTSMZ3v IoVpa6FX2WC7OajGry5WYRwwZgaBu3nz1m+BRoQc= 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 4.14 046/167] bcache: avoid clang -Wunintialized warning Date: Wed, 22 May 2019 15:26:41 -0400 Message-Id: <20190522192842.25858-46-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190522192842.25858-1-sashal@kernel.org> References: <20190522192842.25858-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@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 8c13a9036d07f..ada94a01e1423 100644 --- a/drivers/md/bcache/alloc.c +++ b/drivers/md/bcache/alloc.c @@ -325,10 +325,11 @@ 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