Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753982AbaBRXBN (ORCPT ); Tue, 18 Feb 2014 18:01:13 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:51136 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753311AbaBRWrI (ORCPT ); Tue, 18 Feb 2014 17:47:08 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lior Amsalem , Thomas Petazzoni , Jason Cooper Subject: [PATCH 3.13 10/40] irqchip: armada-370-xp: fix MSI race condition Date: Tue, 18 Feb 2014 14:47:11 -0800 Message-Id: <20140218224433.626357511@linuxfoundation.org> X-Mailer: git-send-email 1.8.5.1.163.gd7aced9 In-Reply-To: <20140218224433.337299968@linuxfoundation.org> References: <20140218224433.337299968@linuxfoundation.org> User-Agent: quilt/0.61-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lior Amsalem commit c7f7bd4a136e4b02dd2a66bf95aec545bd93e8db upstream. In the Armada 370/XP driver, when we receive an IRQ 1, we read the list of doorbells that caused the interrupt from register ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS. This gives the list of MSIs that were generated. However, instead of acknowledging only the MSIs that were generated, we acknowledge *all* the MSIs, by writing ~MSI_DOORBELL_MASK in the ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS register. This creates a race condition: if a new MSI that isn't part of the ones read into the temporary "msimask" variable is fired before we acknowledge all MSIs, then we will simply loose it. It is important to mention that this ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS register has the following behavior: "A CPU write of 0 clears the bits in this field. A CPU write of 1 has no effect". This is what allows us to simply write ~msimask to acknoledge the handled MSIs. Notice that the same problem is present in the IPI implementation, but it is fixed as a separate patch, so that this IPI fix can be pushed to older stable versions as appropriate (all the way to 3.8), while the MSI code only appeared in 3.13. Signed-off-by: Lior Amsalem Signed-off-by: Thomas Petazzoni Signed-off-by: Jason Cooper Signed-off-by: Greg Kroah-Hartman --- drivers/irqchip/irq-armada-370-xp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/irqchip/irq-armada-370-xp.c +++ b/drivers/irqchip/irq-armada-370-xp.c @@ -381,7 +381,7 @@ armada_370_xp_handle_irq(struct pt_regs ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS) & PCI_MSI_DOORBELL_MASK; - writel(~PCI_MSI_DOORBELL_MASK, per_cpu_int_base + + writel(~msimask, per_cpu_int_base + ARMADA_370_XP_IN_DRBEL_CAUSE_OFFS); for (msinr = PCI_MSI_DOORBELL_START; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/