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=-24.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,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 E4005C433ED for ; Thu, 29 Apr 2021 15:10:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A78FD61447 for ; Thu, 29 Apr 2021 15:10:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235023AbhD2PK4 (ORCPT ); Thu, 29 Apr 2021 11:10:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:34462 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233480AbhD2PKy (ORCPT ); Thu, 29 Apr 2021 11:10:54 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D24A4613F8; Thu, 29 Apr 2021 15:10:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1619709007; bh=F83HiRYb/7vD0NCwP6T7zsoqGk6EPDrxndew4NKOdR0=; h=From:To:Cc:Subject:Date:From; b=Ed791e2JdBeC0+P66pUV1zAcp3U68ddtHMcjmSjyDOpfAef+xO2iAPqznf8WIbKZq XqJ8cdYBNI3Ota25TJ6nOlHjUcCWc4odfkE6NiiPEA986UfDuK2WmaBFUvtlBBmzX9 FPQsRefC/89GU7LHWpC7saLqmGrpkYGkl4jK6sbja9wpGeHzF81vYnUiK0jJif1p9K AhWkPseRCeF5UnHOGyK+gemHLjkWe7hm/KTVV10ubCtOsBY9Fq6uitz50iBbVYa+Wy YC/LaPEQaJxoF4NxRiOY5u2ykE1YP1VFQESC/+5+9oIFVGbZ34RtTV5D8vpSTSO3Pr 1WwPVYs/93wxw== From: Arnd Bergmann To: linux-kernel@vger.kernel.org Cc: Arnd Bergmann , Jens Axboe , Jian Cai , Guenter Roeck , Peter Zijlstra , "Huang, Ying" , Borislav Petkov , Eric Dumazet , Juergen Gross , Michael Ellerman , Thomas Gleixner Subject: [PATCH] smp: fix smp_call_function_single_async prototype Date: Thu, 29 Apr 2021 17:09:40 +0200 Message-Id: <20210429150940.3256656-1-arnd@kernel.org> X-Mailer: git-send-email 2.29.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Arnd Bergmann As of commit 966a967116e6 ("smp: Avoid using two cache lines for struct call_single_data"), the smp code prefers 32-byte aligned call_single_data objects for performance reasons, but the block layer includes an instance of this structure in the main 'struct request' that is more senstive to size than to performance here, see 4ccafe032005 ("block: unalign call_single_data in struct request"). The result is a violation of the calling conventions that clang correctly points out: block/blk-mq.c:630:39: warning: passing 8-byte aligned argument to 32-byte aligned parameter 2 of 'smp_call_function_single_async' may result in an unaligned pointer access [-Walign-mismatch] smp_call_function_single_async(cpu, &rq->csd); It does seem that the usage of the call_single_data without cache line alignment should still be allowed by the smp code, so just change the function prototype so it accepts both, but leave the default alignment unchanged for the other users. This seems better to me than adding a local hack to shut up an otherwise correct warning in the caller. Link: https://lore.kernel.org/linux-block/20210330230249.709221-1-jiancai@google.com/ Link: https://github.com/ClangBuiltLinux/linux/issues/1328 Cc: Jens Axboe Cc: Jian Cai Cc: Guenter Roeck Cc: Peter Zijlstra Cc: "Huang, Ying" Cc: Borislav Petkov Cc: Eric Dumazet Cc: Juergen Gross Cc: Michael Ellerman Cc: Thomas Gleixner Signed-off-by: Arnd Bergmann --- include/linux/smp.h | 2 +- kernel/smp.c | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/include/linux/smp.h b/include/linux/smp.h index 669e35c03be2..510519e8a1eb 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -53,7 +53,7 @@ int smp_call_function_single(int cpuid, smp_call_func_t func, void *info, void on_each_cpu_cond_mask(smp_cond_func_t cond_func, smp_call_func_t func, void *info, bool wait, const struct cpumask *mask); -int smp_call_function_single_async(int cpu, call_single_data_t *csd); +int smp_call_function_single_async(int cpu, struct __call_single_data *csd); /* * Cpus stopping functions in panic. All have default weak definitions. diff --git a/kernel/smp.c b/kernel/smp.c index e21074900006..1ec771d9f91c 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -401,7 +401,7 @@ static void __csd_lock_wait(call_single_data_t *csd) smp_acquire__after_ctrl_dep(); } -static __always_inline void csd_lock_wait(call_single_data_t *csd) +static __always_inline void csd_lock_wait(struct __call_single_data *csd) { if (static_branch_unlikely(&csdlock_debug_enabled)) { __csd_lock_wait(csd); @@ -501,7 +501,7 @@ void __smp_call_single_queue(int cpu, struct llist_node *node) * for execution on the given CPU. data must already have * ->func, ->info, and ->flags set. */ -static int generic_exec_single(int cpu, call_single_data_t *csd) +static int generic_exec_single(int cpu, struct __call_single_data *csd) { if (cpu == smp_processor_id()) { smp_call_func_t func = csd->func; @@ -784,7 +784,7 @@ EXPORT_SYMBOL(smp_call_function_single); * NOTE: Be careful, there is unfortunately no current debugging facility to * validate the correctness of this serialization. */ -int smp_call_function_single_async(int cpu, call_single_data_t *csd) +int smp_call_function_single_async(int cpu, struct __call_single_data *csd) { int err = 0; -- 2.29.2