From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754871AbaC3XvF (ORCPT ); Sun, 30 Mar 2014 19:51:05 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:37332 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754732AbaC3Xno (ORCPT ); Sun, 30 Mar 2014 19:43:44 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Stanislaw Gruszka" , "Alan Stern" , "Greg Kroah-Hartman" Date: Mon, 31 Mar 2014 00:23:35 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 145/200] usb: ehci: fix deadlock when threadirqs option is used In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.56-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Stanislaw Gruszka commit a1227f3c1030e96ebc51d677d2f636268845c5fb upstream. ehci_irq() and ehci_hrtimer_func() can deadlock on ehci->lock when threadirqs option is used. To prevent the deadlock use spin_lock_irqsave() in ehci_irq(). This change can be reverted when hrtimer callbacks become threaded. Signed-off-by: Stanislaw Gruszka Acked-by: Alan Stern Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/usb/host/ehci-hcd.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) --- a/drivers/usb/host/ehci-hcd.c +++ b/drivers/usb/host/ehci-hcd.c @@ -807,8 +807,15 @@ static irqreturn_t ehci_irq (struct usb_ struct ehci_hcd *ehci = hcd_to_ehci (hcd); u32 status, masked_status, pcd_status = 0, cmd; int bh; + unsigned long flags; - spin_lock (&ehci->lock); + /* + * For threadirqs option we use spin_lock_irqsave() variant to prevent + * deadlock with ehci hrtimer callback, because hrtimer callbacks run + * in interrupt context even when threadirqs is specified. We can go + * back to spin_lock() variant when hrtimer callbacks become threaded. + */ + spin_lock_irqsave(&ehci->lock, flags); status = ehci_readl(ehci, &ehci->regs->status); @@ -826,7 +833,7 @@ static irqreturn_t ehci_irq (struct usb_ /* Shared IRQ? */ if (!masked_status || unlikely(ehci->rh_state == EHCI_RH_HALTED)) { - spin_unlock(&ehci->lock); + spin_unlock_irqrestore(&ehci->lock, flags); return IRQ_NONE; } @@ -929,7 +936,7 @@ dead: if (bh) ehci_work (ehci); - spin_unlock (&ehci->lock); + spin_unlock_irqrestore(&ehci->lock, flags); if (pcd_status) usb_hcd_poll_rh_status(hcd); return IRQ_HANDLED;