linux-kernel - Re: [PATCH] ibmvnic: Use -EBUSY in __ibmvnic

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Message-ID: <da19d324-3c66-4bb1-8fa2-dc26dbea622b@moroto.mountain>
Date: Tue, 23 Apr 2024 14:55:10 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Paolo Abeni <pabeni@...hat.com>
Cc: Markus Elfring <Markus.Elfring@....de>, linuxppc-dev@...ts.ozlabs.org,
	netdev@...r.kernel.org, kernel-janitors@...r.kernel.org,
	"Aneesh Kumar K.V" <aneesh.kumar@...nel.org>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Haren Myneni <haren@...ux.ibm.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	"Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
	Nicholas Piggin <npiggin@...il.com>,
	Nick Child <nnac123@...ux.ibm.com>,
	Rick Lindsley <ricklind@...ux.ibm.com>,
	Thomas Falcon <tlfalcon@...ux.ibm.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ibmvnic: Use -EBUSY in __ibmvnic_reset()

On Tue, Apr 23, 2024 at 12:54:55PM +0200, Paolo Abeni wrote:
> On Fri, 2024-04-19 at 16:08 +0200, Markus Elfring wrote:
> > From: Markus Elfring <elfring@...rs.sourceforge.net>
> > Date: Fri, 19 Apr 2024 15:46:17 +0200
> > 
> > Add a minus sign before the error code “EBUSY”
> > so that a negative value will be used as in other cases.
> > 
> > This issue was transformed by using the Coccinelle software.
> > 
> > Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> > ---
> >  drivers/net/ethernet/ibm/ibmvnic.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
> > index 5e9a93bdb518..737ae83a836a 100644
> > --- a/drivers/net/ethernet/ibm/ibmvnic.c
> > +++ b/drivers/net/ethernet/ibm/ibmvnic.c
> > @@ -3212,7 +3212,7 @@ static void __ibmvnic_reset(struct work_struct *work)
> >  		    adapter->state == VNIC_REMOVED) {
> >  			spin_unlock_irqrestore(&adapter->state_lock, flags);
> >  			kfree(rwi);
> > -			rc = EBUSY;
> > +			rc = -EBUSY;
> >  			break;
> > 
> 
> AFAICS the error is always used as bool, so this will not change any
> behavior in practice. I tend to think we should not merge this kind of
> change outside some larger work in the same area, but I'd love a second
> opinion from the driver owners.

I missed the original patch due to my procmail filters...

You're right that it doesn't affect the behavior of the driver except
for the debug output when we do:

	netdev_dbg(adapter->netdev, "Reset failed, rc=%d\n", rc);

But the - was left off uninitentionally so I think we should apply it.

I have been trying to look for similar bugs where the - is left off.
It's a bit challenging because there places where we use positive
error codes deliberately.  But in this case a static checker could
easily detect the bug with a low false positive ratio by saying, "We're
mixing normal negative error codes with positive EBUSY".

regards,
dan carpenter