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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3ED75C433EF for ; Thu, 10 Feb 2022 18:35:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343493AbiBJSfy (ORCPT ); Thu, 10 Feb 2022 13:35:54 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:58756 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242663AbiBJSfv (ORCPT ); Thu, 10 Feb 2022 13:35:51 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 9529F25C2; Thu, 10 Feb 2022 10:35:51 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 47F3CD6E; Thu, 10 Feb 2022 10:35:51 -0800 (PST) Received: from [10.57.70.89] (unknown [10.57.70.89]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BA1683F70D; Thu, 10 Feb 2022 10:35:49 -0800 (PST) Message-ID: <7b2761d1-3b4e-d725-cd8d-79591fe9bd86@arm.com> Date: Thu, 10 Feb 2022 18:35:45 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Subject: Re: [PATCH] ACPI/IORT: Fix GCC 12 warning Content-Language: en-GB To: Victor Erminpour , lorenzo.pieralisi@arm.com Cc: guohanjun@huawei.com, sudeep.holla@arm.com, rafael@kernel.org, lenb@kernel.org, linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, trivial@kernel.org References: <1644453141-1181-1-git-send-email-victor.erminpour@oracle.com> <85bbc0e8-7709-71bc-41ba-9c2f0b2e717d@oracle.com> From: Robin Murphy In-Reply-To: <85bbc0e8-7709-71bc-41ba-9c2f0b2e717d@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022-02-10 18:27, Victor Erminpour wrote: > > On 2/10/22 10:06 AM, Robin Murphy wrote: >> On 2022-02-10 00:32, Victor Erminpour wrote: >>> When building with automatic stack variable initialization, GCC 12 >>> complains about variables defined outside of switch case statements. >>> Move the variable into the case that uses it, which silences the >>> warning: >>> >>> ./drivers/acpi/arm64/iort.c:1670:59: error: statement will never be >>> executed [-Werror=switch-unreachable] >>>    1670 |                         struct acpi_iort_named_component >>> *ncomp; >>> | ^~~~~ >> >> Notwithstanding the fact that that warning is nonsensical, this patch >> changes valid C code into invalid C code that doesn't even compile: >> >> drivers/acpi/arm64/iort.c: In function >> ‘acpi_iort_dma_get_max_cpu_address’: >> drivers/acpi/arm64/iort.c:1669:4: error: a label can only be part of a >> statement and a declaration is not a statement >>  1669 |    struct acpi_iort_named_component *ncomp; >>       |    ^~~~~~ >> drivers/acpi/arm64/iort.c:1676:4: error: a label can only be part of a >> statement and a declaration is not a statement >>  1676 |    struct acpi_iort_root_complex *rc; >>       |    ^~~~~~ >> >> Robin. >> > > Hi Robin, > > Thank you for your constructive criticism. > Could the solution be enclosing the case statement in curly braces? > > I know this isn't a big issue for you, but this is a legitimate error > for people > building the kernel with GCC 12 and CONFIG_INIT_STACK_ALL_ZERO enabled. As Ard pointed out first, it is not a legitimate error, it is a spurious error. The fact that you seemingly didn't get the label errors above, nor even "ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement]", implies that GCC 12 currently has a completely broken notion of declarations vs. statements with that option enabled, so GCC 12 needs fixing. Robin. > > Regards, > --Victor > > > >>> Signed-off-by: Victor Erminpour >>> --- >>>   drivers/acpi/arm64/iort.c | 8 +++----- >>>   1 file changed, 3 insertions(+), 5 deletions(-) >>> >>> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c >>> index 3b23fb775ac4..5c5d2e56d756 100644 >>> --- a/drivers/acpi/arm64/iort.c >>> +++ b/drivers/acpi/arm64/iort.c >>> @@ -1645,7 +1645,7 @@ void __init acpi_iort_init(void) >>>    */ >>>   phys_addr_t __init acpi_iort_dma_get_max_cpu_address(void) >>>   { >>> -    phys_addr_t limit = PHYS_ADDR_MAX; >>> +    phys_addr_t local_limit, limit = PHYS_ADDR_MAX; >>>       struct acpi_iort_node *node, *end; >>>       struct acpi_table_iort *iort; >>>       acpi_status status; >>> @@ -1667,17 +1667,15 @@ phys_addr_t __init >>> acpi_iort_dma_get_max_cpu_address(void) >>>               break; >>>             switch (node->type) { >>> -            struct acpi_iort_named_component *ncomp; >>> -            struct acpi_iort_root_complex *rc; >>> -            phys_addr_t local_limit; >>> - >>>           case ACPI_IORT_NODE_NAMED_COMPONENT: >>> +            struct acpi_iort_named_component *ncomp; >>>               ncomp = (struct acpi_iort_named_component >>> *)node->node_data; >>>               local_limit = DMA_BIT_MASK(ncomp->memory_address_limit); >>>               limit = min_not_zero(limit, local_limit); >>>               break; >>>             case ACPI_IORT_NODE_PCI_ROOT_COMPLEX: >>> +            struct acpi_iort_root_complex *rc; >>>               if (node->revision < 1) >>>                   break; >>> >>> _______________________________________________ >>> linux-arm-kernel mailing list >>> linux-arm-kernel@lists.infradead.org >>> https://urldefense.com/v3/__http://lists.infradead.org/mailman/listinfo/linux-arm-kernel__;!!ACWV5N9M2RV99hQ!ZcNRWTaQIb1uVqcZAusSzXd2kBnWuqAuICpxkOm6bOWBouQoFygbcIMJVUNp34LqhNrc$ >> >>