From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754336Ab1HDUqS (ORCPT ); Thu, 4 Aug 2011 16:46:18 -0400 Received: from www.linutronix.de ([62.245.132.108]:33754 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753234Ab1HDUqM (ORCPT ); Thu, 4 Aug 2011 16:46:12 -0400 Date: Thu, 4 Aug 2011 22:46:06 +0200 From: Sebastian Andrzej Siewior To: "Michael S. Tsirkin" Cc: Chris Wright , "Hans J. Koch" , Jesse Barnes , Greg Kroah-Hartman , Anthony Foiani , linux-kernel@vger.kernel.org Subject: [PATCH] uio/gen-pci: don't enable interrupts in ISR Message-ID: <20110804204606.GA19724@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline X-Key-Id: 97C4700B X-Key-Fingerprint: 09E2 D1F3 9A3A FF13 C3D3 961C 0688 1C1E 97C4 700B User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org As reported by Anthony in a short way: |irq 17 handler uio_interrupt+0x0/0x68 enabled interrupts |NIP [c0069d84] handle_irq_event_percpu+0x260/0x26c The problem here is that spin_unlock_irq() enables the interrupts which is a no-no in interrupt context because they always run with interrupts disabled. This is the case even if IRQF_DISABLED has not been specified since v2.6.35. Therefore this patch uses simple spin_locks(). Looking at it further here is only one spot where the lock is hold. So giving the fact that an ISR is not reentrant and is not executed on two cpus at the same time why do we need a lock here? The driver lacks of ->irqcontrol function so I guess the interrupt is enabled via direct PCI-access in userland. So there is _no_ protection against read-modify-write of user vs kernel so even that pci_block_user_cfg_access() is kinda pointless. pci_block_user_cfg_access() in open() + ->irqcontrol() should fix this. Since changes the API of this driver I leave it up to the relevant users what to do. Cc: # .35 and later Reported-and-Tested-by: Anthony Foiani Signed-off-by: Sebastian Andrzej Siewior --- drivers/uio/uio_pci_generic.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/uio/uio_pci_generic.c b/drivers/uio/uio_pci_generic.c index fc22e1e..5c82681 100644 --- a/drivers/uio/uio_pci_generic.c +++ b/drivers/uio/uio_pci_generic.c @@ -57,7 +57,7 @@ static irqreturn_t irqhandler(int irq, struct uio_info *info) BUILD_BUG_ON(PCI_COMMAND % 4); BUILD_BUG_ON(PCI_COMMAND + 2 != PCI_STATUS); - spin_lock_irq(&gdev->lock); + spin_lock(&gdev->lock); pci_block_user_cfg_access(pdev); /* Read both command and status registers in a single 32-bit operation. @@ -83,7 +83,7 @@ static irqreturn_t irqhandler(int irq, struct uio_info *info) done: pci_unblock_user_cfg_access(pdev); - spin_unlock_irq(&gdev->lock); + spin_unlock(&gdev->lock); return ret; } -- 1.7.4.4