linux-kernel - Re: [PATCH -next] RDMA/mlx5: fix type warning of sizeof in __mlx5_ib_alloc

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Message-ID: <20200917172451.GK8409@ziepe.ca>
Date:   Thu, 17 Sep 2020 14:24:51 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Leon Romanovsky <leon@...nel.org>
Cc:     Liu Shixin <liushixin2@...wei.com>,
        Doug Ledford <dledford@...hat.com>, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH -next] RDMA/mlx5: fix type warning of sizeof in
 __mlx5_ib_alloc_counters()

On Thu, Sep 17, 2020 at 08:05:11PM +0300, Leon Romanovsky wrote:
> On Thu, Sep 17, 2020 at 09:38:06AM -0300, Jason Gunthorpe wrote:
> > On Thu, Sep 17, 2020 at 12:08:10PM +0300, Leon Romanovsky wrote:
> > > On Thu, Sep 17, 2020 at 05:10:08PM +0800, Liu Shixin wrote:
> > > > sizeof() when applied to a pointer typed expression should give the
> > > > size of the pointed data, even if the data is a pointer.
> > > >
> > > > Signed-off-by: Liu Shixin <liushixin2@...wei.com>
> >
> > Needs a fixes line
> >
> > > >  	if (!cnts->names)
> > > >  		return -ENOMEM;
> > > >
> > > >  	cnts->offsets = kcalloc(num_counters,
> > > > -				sizeof(cnts->offsets), GFP_KERNEL);
> > > > +				sizeof(*cnts->offsets), GFP_KERNEL);
> > >
> > > This is not.
> >
> > Why not?
> 
> cnts->offsets is array of pointers that we will set later.
> The "sizeof(*cnts->offsets)" will return the size of size_t, while we
> need to get "size_t *".

Then why isn't a pointer to size **?

Something is rotten here

Jason