linux-kernel - Re: [PATCH net-next] mlx5: Restore err assignment in mlx5_mdev

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Message-ID: <20200602070730.GA12686@unreal>
Date:   Tue, 2 Jun 2020 10:07:30 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Nathan Chancellor <natechancellor@...il.com>
Cc:     Saeed Mahameed <saeedm@...lanox.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        linux-rdma@...r.kernel.org, Parav Pandit <parav@...lanox.com>,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: Re: [PATCH net-next] mlx5: Restore err assignment in mlx5_mdev_init

On Mon, Jun 01, 2020 at 09:07:48PM -0700, Nathan Chancellor wrote:
> On Sun, May 31, 2020 at 12:58:10PM +0300, Leon Romanovsky wrote:
> > On Fri, May 29, 2020 at 10:54:48PM -0700, Nathan Chancellor wrote:
> > > Clang warns:
> > >
> > > drivers/net/ethernet/mellanox/mlx5/core/main.c:1278:6: warning: variable
> > > 'err' is used uninitialized whenever 'if' condition is true
> > > [-Wsometimes-uninitialized]
> > >         if (!priv->dbg_root) {
> > >             ^~~~~~~~~~~~~~~
> > > drivers/net/ethernet/mellanox/mlx5/core/main.c:1303:9: note:
> > > uninitialized use occurs here
> > >         return err;
> > >                ^~~
> > > drivers/net/ethernet/mellanox/mlx5/core/main.c:1278:2: note: remove the
> > > 'if' if its condition is always false
> > >         if (!priv->dbg_root) {
> > >         ^~~~~~~~~~~~~~~~~~~~~~
> > > drivers/net/ethernet/mellanox/mlx5/core/main.c:1259:9: note: initialize
> > > the variable 'err' to silence this warning
> > >         int err;
> > >                ^
> > >                 = 0
> > > 1 warning generated.
> > >
> > > This path previously returned -ENOMEM, restore that error code so that
> > > it is not uninitialized.
> > >
> > > Fixes: 810cbb25549b ("net/mlx5: Add missing mutex destroy")
> > > Link: https://github.com/ClangBuiltLinux/linux/issues/1042
> > > Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
> > > ---
> > >  drivers/net/ethernet/mellanox/mlx5/core/main.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/main.c b/drivers/net/ethernet/mellanox/mlx5/core/main.c
> > > index df46b1fce3a7..ac68445fde2d 100644
> > > --- a/drivers/net/ethernet/mellanox/mlx5/core/main.c
> > > +++ b/drivers/net/ethernet/mellanox/mlx5/core/main.c
> > > @@ -1277,6 +1277,7 @@ static int mlx5_mdev_init(struct mlx5_core_dev *dev, int profile_idx)
> > >  					    mlx5_debugfs_root);
> > >  	if (!priv->dbg_root) {
> > >  		dev_err(dev->device, "mlx5_core: error, Cannot create debugfs dir, aborting\n");
> > > +		err = -ENOMEM;
> > >  		goto err_dbg_root;
> >                 ^^^^^^^^^^^^^^^^^^ this is wrong.
> > Failure to create debugfs should never fail the driver.
>
> Fair enough, could you guys deal with this then to make sure it gets
> fixed properly? It appears to be introduced in 11f3b84d7068 ("net/mlx5:
> Split mdev init and pci init").

Thanks, I will send it today.

>
> > >  	}
> > >
> > >
> > > base-commit: c0cc73b79123e67b212bd537a7af88e52c9fbeac
> > > --
> > > 2.27.0.rc0
> > >