From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752187Ab1HJIkR (ORCPT ); Wed, 10 Aug 2011 04:40:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:1221 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751235Ab1HJIkP (ORCPT ); Wed, 10 Aug 2011 04:40:15 -0400 Date: Wed, 10 Aug 2011 11:40:12 +0300 From: "Michael S. Tsirkin" To: "Hans J. Koch" Cc: Sebastian Andrzej Siewior , Chris Wright , Jesse Barnes , Greg Kroah-Hartman , Anthony Foiani , linux-kernel@vger.kernel.org, stable@kernel.org Subject: Re: [PATCH] uio/gen-pci: don't enable interrupts in ISR Message-ID: <20110810084012.GD13911@redhat.com> References: <20110804204606.GA19724@linutronix.de> <20110804210413.GA29222@redhat.com> <20110805001507.GA5987@local> <20110808062431.GB5182@redhat.com> <20110808171931.GB867@local> <20110809113743.GA32299@redhat.com> <20110809185341.GD4229@local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110809185341.GD4229@local> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 09, 2011 at 08:53:41PM +0200, Hans J. Koch wrote: > On Tue, Aug 09, 2011 at 02:37:43PM +0300, Michael S. Tsirkin wrote: > > > > > > Should I hack up a patch to remove the lock, or do you have anything in your > > > pipeline? > > > > > > Please do. > > > > Here it is: > > Greg (and anyone else...), you can also pull this from branch "uio-for-greg" from > > git://hansjkoch.de/git/linux-hjk > > > >From ff74627ade002d40fe1f902b7aadab8b1f15f889 Mon Sep 17 00:00:00 2001 > From: "Hans J. Koch" > Date: Tue, 9 Aug 2011 20:34:31 +0200 > Subject: [PATCH] uio: uio_pci_generic: Remove useless spin_lock > > The spin_lock in uio_pci_generic.c is only used in the interrupt > handler, which cannot be executed twice at the same time. > That makes the lock rather pointless. This patch removes it. > > Cc: "Michael S. Tsirkin" > Cc: Chris Wright > Cc: Jesse Barnes > Cc: Sebastian Andrzej Siewior > Cc: Anthony Foiani > Reported-by: Anthony Foiani > Reported-by: Sebastian Andrzej Siewior > Signed-off-by: Hans J. Koch Acked-by: Michael S. Tsirkin I also suggest this for the stable trees. > --- > drivers/uio/uio_pci_generic.c | 5 ----- > 1 files changed, 0 insertions(+), 5 deletions(-) > > diff --git a/drivers/uio/uio_pci_generic.c b/drivers/uio/uio_pci_generic.c > index fc22e1e..02bd47b 100644 > --- a/drivers/uio/uio_pci_generic.c > +++ b/drivers/uio/uio_pci_generic.c > @@ -24,7 +24,6 @@ > #include > #include > #include > -#include > > #define DRIVER_VERSION "0.01.0" > #define DRIVER_AUTHOR "Michael S. Tsirkin " > @@ -33,7 +32,6 @@ > struct uio_pci_generic_dev { > struct uio_info info; > struct pci_dev *pdev; > - spinlock_t lock; /* guards command register accesses */ > }; > > static inline struct uio_pci_generic_dev * > @@ -57,7 +55,6 @@ 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); > pci_block_user_cfg_access(pdev); > > /* Read both command and status registers in a single 32-bit operation. > @@ -83,7 +80,6 @@ static irqreturn_t irqhandler(int irq, struct uio_info *info) > done: > > pci_unblock_user_cfg_access(pdev); > - spin_unlock_irq(&gdev->lock); > return ret; > } > > @@ -158,7 +154,6 @@ static int __devinit probe(struct pci_dev *pdev, > gdev->info.irq_flags = IRQF_SHARED; > gdev->info.handler = irqhandler; > gdev->pdev = pdev; > - spin_lock_init(&gdev->lock); > > if (uio_register_device(&pdev->dev, &gdev->info)) > goto err_register; > -- > 1.7.5.4