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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 50725C19F2C for ; Tue, 16 Aug 2022 06:24:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date: Message-ID:From:References:To:Subject:CC:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=F3XAZvX2HTEUICX6LTpEjhLG6jJYFPIAtfRaj09IKXI=; b=F7bOLx3DzL70D1lH6r4Ox15jar helm+JkpxgVRbqxYmT+YZJcq9NWxlFSqMqGpevOTcDwTJJ7qKYr/SdpvOjbb2IajXgJruci+Ww78Y WpVzF9K98+O3xzi/I5U90YdwqqNIQfTXwSaeH9ZyWy0b+9pG8uL4W/GcCqNSYiAC8nYAb2ACaNS2v wktIYMp2zGHbWlOOsIIQond+4debjC1x/jLyzsWaiToXE+WAEM5tPX3aeqAYeXjsCzPBLRmfdcpQx Qr0xlpDUgSM/Kw7t/e2lNpoHbear4H1xLPaRHWsiJ0fxIGeFRjI2krJhc6MtTpyxFgKzEZv5dAqij OV7qY/Yw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oNpyP-00DSsX-3m; Tue, 16 Aug 2022 06:22:45 +0000 Received: from szxga02-in.huawei.com ([45.249.212.188]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oNpy1-00DS4T-SE for linux-arm-kernel@lists.infradead.org; Tue, 16 Aug 2022 06:22:26 +0000 Received: from canpemm500009.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4M6LYP6CCmzXdjj; Tue, 16 Aug 2022 14:18:01 +0800 (CST) Received: from [10.67.102.169] (10.67.102.169) by canpemm500009.china.huawei.com (7.192.105.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Tue, 16 Aug 2022 14:22:12 +0800 CC: , , , , , , , , , , , , , , , , , , Subject: Re: [PATCH] drivers/perf: Change WARN_ON() to dev_err() on irq_set_affinity() failure To: Jonathan Cameron References: <20220815092815.11597-1-yangyicong@huawei.com> <20220815103958.000016c9@huawei.com> From: Yicong Yang Message-ID: <7102b6dc-1721-46cd-bdb4-a3d39e12a82b@huawei.com> Date: Tue, 16 Aug 2022 14:22:12 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 MIME-Version: 1.0 In-Reply-To: <20220815103958.000016c9@huawei.com> X-Originating-IP: [10.67.102.169] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To canpemm500009.china.huawei.com (7.192.105.203) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220815_232223_968434_3E0AAFF3 X-CRM114-Status: GOOD ( 22.22 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2022/8/15 17:39, Jonathan Cameron wrote: > On Mon, 15 Aug 2022 17:28:15 +0800 > Yicong Yang wrote: > >> From: Yicong Yang >> >> The WARN_ON() on irq_set_affinity() failure is misused according to the [1] >> and may crash people's box unintentionally. This may also be redundant since >> in the failure case we may also trigger the WARN and dump the stack in the >> perf core[2] for a second time. >> >> So change the WARN_ON() to dev_err() to just print the failure message. >> >> [1] https://github.com/torvalds/linux/blob/master/include/asm-generic/bug.h#L74 >> [2] https://github.com/torvalds/linux/blob/master/kernel/events/core.c#L313 >> >> Suggested-by: Greg KH >> [https://lore.kernel.org/lkml/YuOi3i0XHV++z1YI@kroah.com/] >> Signed-off-by: Yicong Yang > > Looks like progress in a sensible direction to me. > > Reviewed-by: Jonathan Cameron > > Kind of unrelated question inline. > Thanks for the quick review! replies below. >> > > >> diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c >> index 00d4c45a8017..05e1b3e274d7 100644 >> --- a/drivers/perf/arm_smmuv3_pmu.c >> +++ b/drivers/perf/arm_smmuv3_pmu.c >> @@ -646,7 +646,8 @@ static int smmu_pmu_offline_cpu(unsigned int cpu, struct hlist_node *node) >> >> perf_pmu_migrate_context(&smmu_pmu->pmu, cpu, target); >> smmu_pmu->on_cpu = target; >> - WARN_ON(irq_set_affinity(smmu_pmu->irq, cpumask_of(target))); >> + if (irq_set_affinity(smmu_pmu->irq, cpumask_of(target))) >> + dev_err(smmu_pmu->dev, "Failed to set interrupt affinity\n"); >> >> return 0; >> } >> @@ -892,7 +893,8 @@ static int smmu_pmu_probe(struct platform_device *pdev) >> >> /* Pick one CPU to be the preferred one to use */ >> smmu_pmu->on_cpu = raw_smp_processor_id(); >> - WARN_ON(irq_set_affinity(smmu_pmu->irq, cpumask_of(smmu_pmu->on_cpu))); >> + if (irq_set_affinity(smmu_pmu->irq, cpumask_of(smmu_pmu->on_cpu))) >> + dev_err(dev, "Failed to set interrupt affinity\n"); > > In this case we have the option to fail probe. Failing to set affinity means > we are broken anyway, so perhaps that is cleaner than carrying on. > This patch only switch the way on error notification with no functional change intended. So if we need to change the behaviour here it should be in a separate patch. Indeed I'm not sure it's necessary to fail probe here since we can use the pmu if it fails here. > As a side note, I wonder if other drivers could benefit from what I think > is a micro optimization to short cut calling the hp handlers when the > decision of which CPU is easy... > It seems sensible to me but may differ in differenct pmu drivers since they may need the hp handlers called. Needs more check. Thanks. >> >> err = cpuhp_state_add_instance_nocalls(cpuhp_state_num, >> &smmu_pmu->node); > . > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel