From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Julia Lawall <julia.lawall@inria.fr>
Cc: kernel-janitors@vger.kernel.org,
Jiri Slaby <jirislaby@kernel.org>,
linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 01/14] pch_uart: drop double zeroing
Date: Sun, 27 Sep 2020 14:11:36 +0200 [thread overview]
Message-ID: <20200927121136.GA164938@kroah.com> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2009201443590.2966@hadrien>
On Sun, Sep 20, 2020 at 02:47:11PM +0200, Julia Lawall wrote:
>
>
> On Sun, 20 Sep 2020, Greg Kroah-Hartman wrote:
>
> > On Sun, Sep 20, 2020 at 01:26:13PM +0200, Julia Lawall wrote:
> > > sg_init_table zeroes its first argument, so the allocation of that argument
> > > doesn't have to.
> > >
> > > the semantic patch that makes this change is as follows:
> > > (http://coccinelle.lip6.fr/)
> > >
> > > // <smpl>
> > > @@
> > > expression x,n,flags;
> > > @@
> > >
> > > x =
> > > - kcalloc
> > > + kmalloc_array
> > > (n,sizeof(struct scatterlist),flags)
> > > ...
> > > sg_init_table(x,n)
> > > // </smpl>
> > >
> > > Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
> >
> > It inits the first entry in the array, but what about all of the other
> > ones? Is that "safe" to have uninitialized data in them like your
> > change causes to happen?
>
> Sorry, I don't follow. The complete code is:
>
> priv->sg_tx_p = kcalloc(num, sizeof(struct scatterlist), GFP_ATOMIC);
> if (!priv->sg_tx_p) {
> dev_err(priv->port.dev, "%s:kzalloc Failed\n", __func__);
> return 0;
> }
>
> sg_init_table(priv->sg_tx_p, num); /* Initialize SG table */
>
> and the definition of sg_init_table is:
>
> void sg_init_table(struct scatterlist *sgl, unsigned int nents)
> {
> memset(sgl, 0, sizeof(*sgl) * nents);
> sg_init_marker(sgl, nents);
> }
Ah, missed the "* nents" thing there, sorry, my fault.
greg k-h
next prev parent reply other threads:[~2020-09-27 12:11 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-20 11:26 [PATCH 00/14] drop double zeroing Julia Lawall
2020-09-20 11:26 ` [PATCH 01/14] pch_uart: " Julia Lawall
2020-09-20 12:14 ` Greg Kroah-Hartman
2020-09-20 12:47 ` Julia Lawall
2020-09-27 12:11 ` Greg Kroah-Hartman [this message]
2020-09-21 16:58 ` [PATCH 00/14] " Mark Brown
2020-09-23 15:10 ` Rolf Reintjes
2020-09-23 15:16 ` Mark Brown
2020-10-13 22:42 ` Martin K. Petersen
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