linux-kernel - Re: [PATCH] platform/mellanox: mlxreg-lc: fix error code in mlxreg_lc_create_static

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Date:   Thu, 11 Nov 2021 10:39:50 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Mark Gross <markgross@...nel.org>
Cc:     Hans de Goede <hdegoede@...hat.com>,
        Vadim Pasternak <vadimp@...dia.com>,
        Michael Shych <michaelsh@...dia.com>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] platform/mellanox: mlxreg-lc: fix error code in
 mlxreg_lc_create_static_devices()

On Thu, Nov 11, 2021 at 10:33:41AM +0300, Dan Carpenter wrote:
> On Wed, Nov 10, 2021 at 02:31:47PM -0800, Mark Gross wrote:
> > On Wed, Nov 10, 2021 at 10:43:46AM +0300, Dan Carpenter wrote:
> > > This code should be using PTR_ERR() instead of IS_ERR().  And because
> > > it's using the wrong "dev->client" pointer, the IS_ERR() check will be
> > > false, meaning the function returns success.
> > > 
> > > Fixes: 62f9529b8d5c ("platform/mellanox: mlxreg-lc: Add initial support for Nvidia line card devices")
> > > Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> > > ---
> > >  drivers/platform/mellanox/mlxreg-lc.c | 5 +++--
> > >  1 file changed, 3 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/drivers/platform/mellanox/mlxreg-lc.c b/drivers/platform/mellanox/mlxreg-lc.c
> > > index 0b7f58feb701..c897a2f15840 100644
> > > --- a/drivers/platform/mellanox/mlxreg-lc.c
> > > +++ b/drivers/platform/mellanox/mlxreg-lc.c
> > > @@ -413,7 +413,7 @@ mlxreg_lc_create_static_devices(struct mlxreg_lc *mlxreg_lc, struct mlxreg_hotpl
> > >  				int size)
> > >  {
> > >  	struct mlxreg_hotplug_device *dev = devs;
> > > -	int i;
> > > +	int i, ret;
> > >  
> > >  	/* Create static I2C device feeding by auxiliary or main power. */
> > >  	for (i = 0; i < size; i++, dev++) {
> > > @@ -423,6 +423,7 @@ mlxreg_lc_create_static_devices(struct mlxreg_lc *mlxreg_lc, struct mlxreg_hotpl
> > >  				dev->brdinfo->type, dev->nr, dev->brdinfo->addr);
> > >  
> > >  			dev->adapter = NULL;
> > > +			ret = PTR_ERR(dev->client);
> > ret is only set on this error path.
> > can we get to the return without setting ret?
> > 
> 
> No.
> 
> :P
> 
> There two ways to read that question is if the patch introduces an
> uninitialized variable bug and I would be super embarrassed if I did
> something like that with all the QC scripts that I have to prevent it.
> The other way to read that question is if it's possible to not introduce
> the "ret" variable but instead figure it out at the end.  But the error
> code needs to be preserved at this point because we change change the
> "dev" pointer and set "dev->adapter" to NULL.
                         ^^^^^^^^^^^^
I meant "dev->client" not "dev->adapter".

regards,
dan carpenter