From patchwork Thu Jul 27 10:21:11 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Thomas Gleixner X-Patchwork-Id: 9866539 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 4E8246038C for ; Thu, 27 Jul 2017 10:21:55 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3CA98287C8 for ; Thu, 27 Jul 2017 10:21:55 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2FA32287E7; Thu, 27 Jul 2017 10:21:55 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,RCVD_IN_DNSWL_NONE autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [65.50.211.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id A7664287C8 for ; Thu, 27 Jul 2017 10:21:54 +0000 (UTC) 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:MIME-Version: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:In-Reply-To:References: List-Owner; bh=+Zg84/zD8N9G7cHL1dfyRY0MrnC+EfbXQe1c0qPMDHY=; b=iLwIDWfsYwAhYJ kdZ/ytRUs5MrCcvH01YMfpjExywDu0/3Nx+wVGBR2I3JvtmYaQemq02OkqoIavPCPnr983LQAEkPu x+EN2YMJWAdLOBGMFAl/R5++S5vFK6sIPDfQrb2zKvojrs0qu2+LAnQdpWX/w2sjk03Xrs87AGNRl jOUXOBfxjXtRwgoLqbqTK6p/GXGUjgb39ZwC8WK2Blp4vPFNWOl2ruCrEnxEnT7cyfIiZOlWYnemR OKakmdl00x6CzaqeHiqvgZyL3cppP246RLCkHlS0sOpxwIReZT8rcqe/9ycdjkt9NOwwu/Gn8FhJ0 SnxXjWu96OfN0Hyswm9w==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1dafvQ-0007vM-7A; Thu, 27 Jul 2017 10:21:48 +0000 Received: from galois.linutronix.de ([2a01:7a0:2:106d:700::1]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1dafvK-0007tj-T0 for linux-arm-kernel@lists.infradead.org; Thu, 27 Jul 2017 10:21:46 +0000 Received: from localhost ([127.0.0.1]) by Galois.linutronix.de with esmtps (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1dafuQ-0004vA-A3; Thu, 27 Jul 2017 12:20:46 +0200 Date: Thu, 27 Jul 2017 12:21:11 +0200 (CEST) From: Thomas Gleixner To: LKML Subject: [PATCH] genirq/cpuhotplug: Revert "Set force affinity flag on hotplug migration" Message-ID: User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170727_032143_153846_1381FC27 X-CRM114-Status: GOOD ( 16.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Marc Zyngier , Russell King , Will Deacon , LAK Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP That commit was part of the changes moving x86 to the generic CPU hotplug interrupt migration code. The force flag was required on x86 before the hierarchical irqdomain rework, but invoking set_affinity() with force=true stayed and had no side effects. At some point in the past, the force flag got repurposed to support the exynos timer interrupt affinity setting to a not yet online CPU, so the interrupt controller callback does not verify the supplied affinity mask against cpu_online_mask. Setting the flag in the CPU hotplug code causes the cpu online masking to be blocked on these irq controllers and results in potentially affining an interrupt to the CPU which is unplugged, i.e. instead of moving it away, it's just reassigned to it. As the force flags is not longer needed on x86, it's safe to revert that patch so the ARM irqchips which use the force flag work again. Add comments to that effect, so this won't happen again. Note: The online mask handling should be done in the generic code and the force flag and the masking in the irq chips removed all together, but that's not a change possible for 4.13. Fixes: 77f85e66aa8b ("genirq/cpuhotplug: Set force affinity flag on hotplug migration") Reported-by: Will Deacon Signed-off-by: Thomas Gleixner Acked-by: Will Deacon --- include/linux/irq.h | 7 ++++++- kernel/irq/cpuhotplug.c | 9 +++++++-- 2 files changed, 13 insertions(+), 3 deletions(-) --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -388,7 +388,12 @@ static inline irq_hw_number_t irqd_to_hw * @irq_mask_ack: ack and mask an interrupt source * @irq_unmask: unmask an interrupt source * @irq_eoi: end of interrupt - * @irq_set_affinity: set the CPU affinity on SMP machines + * @irq_set_affinity: Set the CPU affinity on SMP machines. If the force + * argument is true, it tells the driver to + * unconditionally apply the affinity setting. Sanity + * checks against the supplied affinity mask are not + * required. This is used for CPU hotplug where the + * target CPU is not yet set in the cpu_online_mask. * @irq_retrigger: resend an IRQ to the CPU * @irq_set_type: set the flow type (IRQ_TYPE_LEVEL/etc.) of an IRQ * @irq_set_wake: enable/disable power-management wake-on of an IRQ --- a/kernel/irq/cpuhotplug.c +++ b/kernel/irq/cpuhotplug.c @@ -95,8 +95,13 @@ static bool migrate_one_irq(struct irq_d affinity = cpu_online_mask; brokeaff = true; } - - err = irq_do_set_affinity(d, affinity, true); + /* + * Do not set the force argument of irq_do_set_affinity() as this + * disables the masking of offline CPUs from the supplied affinity + * mask and therefor might keep/reassign the irq to the outgoing + * CPU. + */ + err = irq_do_set_affinity(d, affinity, false); if (err) { pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n", d->irq, err);