From: Arnd Bergmann <arnd@arndb.de>
To: Namhyung Kim <namhyung@gmail.com>
Subject: Re: [PATCH 2/3 RESEND] ptrace: cleanup address space conversion on ptrace_request()
Date: Tue, 24 Aug 2010 13:45:06 +0200
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Cc: Christoph Hellwig <hch@infradead.org>, Roland McGrath <roland@redhat.com>,
        Oleg Nesterov <oleg@redhat.com>, linux-kernel@vger.kernel.org
References: <201008222206.18523.arnd@arndb.de> <20100823162105.GA19164@infradead.org> <1282581489.1659.13.camel@leonhard>
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On Monday 23 August 2010, Namhyung Kim wrote:
> But removing __force results in following sparse warning:
> 
>  ptrace.c:567:40: warning: cast adds address space to expression
> (<asn:1>)

The problem is that ptrace takes a 'long' argument, not 'unsigned long'.
Sparse complains about adding address spaces in all casts except those
from/to unsigned long, which we often use as an opaque token that can
fit anything.

I don't think we ever rely on 'data' being signed, and user space
sees it as 'void *' anyway, so it should be possible to just turn
it into 'unsigned long'.

	Arnd
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