linux-kernel - Re: [PATCH 01/18] char: moxa: call disable_pci_device() if pci

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Message-ID: <20100807085512.GA5783@albatros>
Date:	Sat, 7 Aug 2010 12:55:12 +0400
From:	Vasiliy Kulikov <segooon@...il.com>
To:	Dan Carpenter <error27@...il.com>, kernel-janitors@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...e.de>,
	Alan Cox <alan@...ux.intel.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rakib Mullick <rakib.mullick@...il.com>,
	Ben Hutchings <ben@...adent.org.uk>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/18] char: moxa: call disable_pci_device() if
 pci_probe() failed

On Sat, Aug 07, 2010 at 09:22 +0200, Dan Carpenter wrote:
> On Fri, Aug 06, 2010 at 11:49:10PM +0400, Kulikov Vasiliy wrote:
> > Driver should call disable_pci_device() if it returns from pci_probe()
> > with error. Also it must not be called if pci_request_region() fails as
> > it means that somebody uses device resources and rules the device.
> > 
> 
> I think we should disable it actually.  The comments on
> pci_enable_device() and pci_disable_device() say that only the first and
> last callers actually enable and disable it.  The others just increment
> or decrement a counter.

See this thread: http://lkml.org/lkml/2005/2/13/82

Specifically this mail:

    Date    Mon, 14 Feb 2005 14:51:26 -0500
    From    Jeff Garzik <>

    ...
    You also need to consider situations such as out-of-tree drivers 
    for the same hardware (might not use PCI API), and situations where you 
    have peer devices discovered and used (PCI API doesn't have "hey, <this> 
    device is associated with <current driver>, too" capability).
    ...

Searching for 'pci_disable_device() inurl:lkml' doesn't give me newer info
aboud this problem, so I think it's better to play safe.


> 
> regards,
> dan carpenter
> 
> > Move pci_enable_device() after checking moxa_boards[] to remove senseless
> > pci_enable_device()/pci_disable_device().
> > 
> > Signed-off-by: Kulikov Vasiliy <segooon@...il.com>
> > ---
> >  drivers/char/moxa.c |   12 +++++++-----
> >  1 files changed, 7 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/char/moxa.c b/drivers/char/moxa.c
> > index 107b0bd..0ea5aeb 100644
> > --- a/drivers/char/moxa.c
> > +++ b/drivers/char/moxa.c
> > @@ -939,11 +939,6 @@ static int __devinit moxa_pci_probe(struct pci_dev *pdev,
> >  	int board_type = ent->driver_data;
> >  	int retval;
> >  
> > -	retval = pci_enable_device(pdev);
> > -	if (retval) {
> > -		dev_err(&pdev->dev, "can't enable pci device\n");
> > -		goto err;
> > -	}
> >  
> >  	for (i = 0; i < MAX_BOARDS; i++)
> >  		if (moxa_boards[i].basemem == NULL)
> > @@ -956,6 +951,12 @@ static int __devinit moxa_pci_probe(struct pci_dev *pdev,
> >  		goto err;
> >  	}
> >  
> > +	retval = pci_enable_device(pdev);
> > +	if (retval) {
> > +		dev_err(&pdev->dev, "can't enable pci device\n");
> > +		goto err;
> > +	}
> > +
> >  	board = &moxa_boards[i];
> >  
> >  	retval = pci_request_region(pdev, 2, "moxa-base");
> > @@ -1001,6 +1002,7 @@ err_base:
> >  	board->basemem = NULL;
> >  err_reg:
> >  	pci_release_region(pdev, 2);
> > +	pci_disable_device(pdev);
> >  err:
> >  	return retval;
> >  }
> > -- 
> > 1.7.0.4
> > 
> > --
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