Messages in this thread | | | Date | Sun, 20 Sep 2020 14:47:11 +0200 (CEST) | From | Julia Lawall <> | Subject | Re: [PATCH 01/14] pch_uart: drop double zeroing |
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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); }
It looks to me like it zeroes all of the elements? The same file does contain a call:
sg_init_table(&priv->sg_rx, 1);
But that's not the one associated with the patch.
julia
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