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=-19.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT 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 B67D2C43216 for ; Mon, 26 Jul 2021 16:26:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9A09D604AC for ; Mon, 26 Jul 2021 16:26:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239300AbhGZPpR (ORCPT ); Mon, 26 Jul 2021 11:45:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:41244 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231362AbhGZP2I (ORCPT ); Mon, 26 Jul 2021 11:28:08 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9419E60FE3; Mon, 26 Jul 2021 16:06:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1627315610; bh=J4AhUA7x+vqG2sywfhNOO/+6xAQSl/Bi+CKhBLBFGoY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ubd/LJ+bNkAOlPV0b8cj6uCdvq0E+1xZhG331VvPV2Aiq68d5c/kav2O5b0Nl+bzS wBiJtsdklOJ/zYOd6FyBQJ09x3ME2oINV9BVkySPvsfHzPqLRs8wepQjngZJQ5SyBp Dod4HxVU+fCpsuivcb2P7U3uDt2nbqFDnGEabDOg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Laurence Oberman , Andy Shevchenko , Alan Stern , David Jeffery Subject: [PATCH 5.10 164/167] usb: ehci: Prevent missed ehci interrupts with edge-triggered MSI Date: Mon, 26 Jul 2021 17:39:57 +0200 Message-Id: <20210726153844.911987832@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210726153839.371771838@linuxfoundation.org> References: <20210726153839.371771838@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Jeffery commit 0b60557230adfdeb8164e0b342ac9cd469a75759 upstream. When MSI is used by the ehci-hcd driver, it can cause lost interrupts which results in EHCI only continuing to work due to a polling fallback. But the reliance of polling drastically reduces performance of any I/O through EHCI. Interrupts are lost as the EHCI interrupt handler does not safely handle edge-triggered interrupts. It fails to ensure all interrupt status bits are cleared, which works with level-triggered interrupts but not the edge-triggered interrupts typical from using MSI. To fix this problem, check if the driver may have raced with the hardware setting additional interrupt status bits and clear status until it is in a stable state. Fixes: 306c54d0edb6 ("usb: hcd: Try MSI interrupts on PCI devices") Tested-by: Laurence Oberman Reviewed-by: Andy Shevchenko Acked-by: Alan Stern Signed-off-by: David Jeffery Link: https://lore.kernel.org/r/20210715213744.GA44506@redhat Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/ehci-hcd.c | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-) --- a/drivers/usb/host/ehci-hcd.c +++ b/drivers/usb/host/ehci-hcd.c @@ -703,7 +703,8 @@ EXPORT_SYMBOL_GPL(ehci_setup); static irqreturn_t ehci_irq (struct usb_hcd *hcd) { struct ehci_hcd *ehci = hcd_to_ehci (hcd); - u32 status, masked_status, pcd_status = 0, cmd; + u32 status, current_status, masked_status, pcd_status = 0; + u32 cmd; int bh; unsigned long flags; @@ -715,19 +716,22 @@ static irqreturn_t ehci_irq (struct usb_ */ spin_lock_irqsave(&ehci->lock, flags); - status = ehci_readl(ehci, &ehci->regs->status); + status = 0; + current_status = ehci_readl(ehci, &ehci->regs->status); +restart: /* e.g. cardbus physical eject */ - if (status == ~(u32) 0) { + if (current_status == ~(u32) 0) { ehci_dbg (ehci, "device removed\n"); goto dead; } + status |= current_status; /* * We don't use STS_FLR, but some controllers don't like it to * remain on, so mask it out along with the other status bits. */ - masked_status = status & (INTR_MASK | STS_FLR); + masked_status = current_status & (INTR_MASK | STS_FLR); /* Shared IRQ? */ if (!masked_status || unlikely(ehci->rh_state == EHCI_RH_HALTED)) { @@ -737,6 +741,12 @@ static irqreturn_t ehci_irq (struct usb_ /* clear (just) interrupts */ ehci_writel(ehci, masked_status, &ehci->regs->status); + + /* For edge interrupts, don't race with an interrupt bit being raised */ + current_status = ehci_readl(ehci, &ehci->regs->status); + if (current_status & INTR_MASK) + goto restart; + cmd = ehci_readl(ehci, &ehci->regs->command); bh = 0;