Re: [PATCH] Fix some sparse warnings

From: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Date: Jul 20, 2013, 19:26 UTC
Message-ID: <51EAE463.4010705@ramsay1.demon.co.uk>
In-Reply-To: <20130718203640.GB15735@sigill.intra.peff.net>

Jeff King wrote:

Show 14 quoted lines

> On Thu, Jul 18, 2013 at 09:25:50PM +0100, Ramsay Jones wrote:
> 
>> Sparse issues some "Using plain integer as NULL pointer" warnings.
>> Each warning relates to the use of an '{0}' initialiser expression
>> in the declaration of an 'struct object_info'. The first field of
>> this structure has pointer type. Thus, in order to suppress these
>> warnings, we replace the initialiser expression with '{NULL}'.
>>
>> Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
> 
> Acked-by: Jeff King <peff@peff.net>
> 
> I thought at first we would need one more for the new callsite I added
> in my series, but we use memset() in that instance, so it is fine.

On an almost unrelated note ... I am now getting the following sparse warnings:

    pack-revindex.c:105:23: warning: memset with byte count of 262144

This is a little annoying, since there is no way to turn this off. :( (which I consider a bug in sparse).

Sparse has special-case code to check calls to memset(), memcpy(), copy_to_user() and copy_from_user(). The code that checks the byte count argument looks like:

static void check_byte_count(struct instruction *insn, pseudo_t count)
{
        if (!count)
                return;
        if (count->type == PSEUDO_VAL) {
                long long val = count->value;
                if (val <= 0 || val > 100000)
                        warning(insn->pos, "%s with byte count of %lld",
                                show_ident(insn->func->sym->ident), val);
                return;
        }
        /* OK, we could try to do the range analysis here */
}

I will just ignore this for now. ;-)

ATB, Ramsay Jones