linux-kernel - Re: [PATCH 01/14] pch_uart: drop double zeroing

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Date:   Sun, 20 Sep 2020 14:14:04 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Julia Lawall <Julia.Lawall@...ia.fr>
Cc:     kernel-janitors@...r.kernel.org, Jiri Slaby <jirislaby@...nel.org>,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/14] pch_uart: drop double zeroing

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@...ia.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?

thanks,

greg k-h