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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 54E9CC3F2D2 for ; Mon, 2 Mar 2020 12:21:46 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 28ABF217F4 for ; Mon, 2 Mar 2020 12:21:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="oi1SRS7d" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 28ABF217F4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=uEDKhOBIUmfuLbJUai6MEelGOUC9fr1b7oMBhj3CTho=; b=oi1SRS7dRBzRvA BSxKWEZgea/7HpHGYCQdC3JZ0XJsPolcEfi/OyK7qQ24M/6i1eE8pHD+4YprtMMvecqPGUxEt/jhI jaeEndy9WltBy/JRVGBmPqeIE0v9MsNK34+z6lZ1Pn0sC0pttmZ2oztPucTdBu+G8AU6MLm0LLKpY DkMMqzrKsCHvf/Cl+5eVE8z6dW0/M+Qc+vwttF9BKzfayzw/nAsJ+sX6+0dJ+mHiEubqwxr9G0smX wKyaIZxp/ePUv/p4lEIH1LkJ3AHYUynmeCT+6I+Y0899uPM3ui3AWg4J/KJHkdUhlme9qgtor/6Nt vLZ8lZ0kgE1RWrseXsfg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j8k4v-0006Yo-L6; Mon, 02 Mar 2020 12:21:45 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j8k4s-0006Xr-0k for linux-arm-kernel@lists.infradead.org; Mon, 02 Mar 2020 12:21:43 +0000 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 C29C82F; Mon, 2 Mar 2020 04:21:38 -0800 (PST) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C34393F534; Mon, 2 Mar 2020 04:21:37 -0800 (PST) Date: Mon, 2 Mar 2020 12:21:35 +0000 From: Mark Rutland To: Gavin Shan Subject: Re: [PATCH] arm64/kernel: Simplify __cpu_up() by bailing out early Message-ID: <20200302122135.GB56497@lakrids.cambridge.arm.com> References: <20200302020340.119588-1-gshan@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200302020340.119588-1-gshan@redhat.com> User-Agent: Mutt/1.11.1+11 (2f07cb52) (2018-12-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200302_042142_154284_B4E9AFBE X-CRM114-Status: GOOD ( 23.10 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: catalin.marinas@arm.com, linux-kernel@vger.kernel.org, shan.gavin@gmail.com, maz@kernel.org, will@kernel.org, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Mar 02, 2020 at 01:03:40PM +1100, Gavin Shan wrote: > The function __cpu_up() is invoked to bring up the target CPU through > the backend, PSCI for example. The nested if statements won't be needed > if we bail out early on the following two conditions where the status > won't be checked. The code looks simplified in that case. > > * Error returned from the backend (e.g. PSCI) > * The target CPU has been marked as onlined > > Signed-off-by: Gavin Shan FWIW, this looks like a nice cleanup to me: Reviewed-by: Mark Rutland While this patch leaves secondary_data.{task,stack} stale on a successful onlining, that was already the case for a timeout, and should be fine (since the next attempt at onlining will configure those before poking the CPU). Thanks, Mark. > --- > arch/arm64/kernel/smp.c | 79 +++++++++++++++++++---------------------- > 1 file changed, 37 insertions(+), 42 deletions(-) > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c > index d4ed9a19d8fe..2a9d8f39dc58 100644 > --- a/arch/arm64/kernel/smp.c > +++ b/arch/arm64/kernel/smp.c > @@ -115,60 +115,55 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle) > update_cpu_boot_status(CPU_MMU_OFF); > __flush_dcache_area(&secondary_data, sizeof(secondary_data)); > > - /* > - * Now bring the CPU into our world. > - */ > + /* Now bring the CPU into our world */ > ret = boot_secondary(cpu, idle); > - if (ret == 0) { > - /* > - * CPU was successfully started, wait for it to come online or > - * time out. > - */ > - wait_for_completion_timeout(&cpu_running, > - msecs_to_jiffies(5000)); > - > - if (!cpu_online(cpu)) { > - pr_crit("CPU%u: failed to come online\n", cpu); > - ret = -EIO; > - } > - } else { > + if (ret) { > pr_err("CPU%u: failed to boot: %d\n", cpu, ret); > return ret; > } > > + /* > + * CPU was successfully started, wait for it to come online or > + * time out. > + */ > + wait_for_completion_timeout(&cpu_running, > + msecs_to_jiffies(5000)); > + if (cpu_online(cpu)) > + return 0; > + > + pr_crit("CPU%u: failed to come online\n", cpu); > secondary_data.task = NULL; > secondary_data.stack = NULL; > __flush_dcache_area(&secondary_data, sizeof(secondary_data)); > status = READ_ONCE(secondary_data.status); > - if (ret && status) { > - > - if (status == CPU_MMU_OFF) > - status = READ_ONCE(__early_cpu_boot_status); > + if (status == CPU_MMU_OFF) > + status = READ_ONCE(__early_cpu_boot_status); > > - switch (status & CPU_BOOT_STATUS_MASK) { > - default: > - pr_err("CPU%u: failed in unknown state : 0x%lx\n", > - cpu, status); > - cpus_stuck_in_kernel++; > - break; > - case CPU_KILL_ME: > - if (!op_cpu_kill(cpu)) { > - pr_crit("CPU%u: died during early boot\n", cpu); > - break; > - } > - pr_crit("CPU%u: may not have shut down cleanly\n", cpu); > - /* Fall through */ > - case CPU_STUCK_IN_KERNEL: > - pr_crit("CPU%u: is stuck in kernel\n", cpu); > - if (status & CPU_STUCK_REASON_52_BIT_VA) > - pr_crit("CPU%u: does not support 52-bit VAs\n", cpu); > - if (status & CPU_STUCK_REASON_NO_GRAN) > - pr_crit("CPU%u: does not support %luK granule \n", cpu, PAGE_SIZE / SZ_1K); > - cpus_stuck_in_kernel++; > + switch (status & CPU_BOOT_STATUS_MASK) { > + default: > + pr_err("CPU%u: failed in unknown state : 0x%lx\n", > + cpu, status); > + cpus_stuck_in_kernel++; > + break; > + case CPU_KILL_ME: > + if (!op_cpu_kill(cpu)) { > + pr_crit("CPU%u: died during early boot\n", cpu); > break; > - case CPU_PANIC_KERNEL: > - panic("CPU%u detected unsupported configuration\n", cpu); > } > + pr_crit("CPU%u: may not have shut down cleanly\n", cpu); > + /* Fall through */ > + case CPU_STUCK_IN_KERNEL: > + pr_crit("CPU%u: is stuck in kernel\n", cpu); > + if (status & CPU_STUCK_REASON_52_BIT_VA) > + pr_crit("CPU%u: does not support 52-bit VAs\n", cpu); > + if (status & CPU_STUCK_REASON_NO_GRAN) { > + pr_crit("CPU%u: does not support %luK granule\n", > + cpu, PAGE_SIZE / SZ_1K); > + } > + cpus_stuck_in_kernel++; > + break; > + case CPU_PANIC_KERNEL: > + panic("CPU%u detected unsupported configuration\n", cpu); > } > > return ret; > -- > 2.23.0 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel