To: linux-kernel@vger.kernel.org
From: Roland Dreier <roland@topspin.com>
Date: Mon, 04 Oct 2004 22:28:55 -0700
Message-ID: <52u0t9u414.fsf@topspin.com>
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Subject: proper way to annotate kernel use of sys_xxx?
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What is the correct way to annotate kernel code that calls a sys_xxx
function that expects a __user pointer as an argument?

To give a concrete example, sparse (among lots of other warnings for
do_mounts.c) says:

	init/do_mounts.c:69:16: warning: incorrect type in argument 1 (different address spaces)
	init/do_mounts.c:69:16:    expected char const [noderef] *filename<asn:1>
	init/do_mounts.c:69:16:    got char [addressable] *<noident>

The code in question is the following:

	char path[64];

	/* ... */

	sprintf(path, "/sys/block/%s/dev", name);
	fd = sys_open(path, 0, 0);                 /* LINE 69 */

This is an abuse of sys_open(), but we know it's OK.  Is the right way
to shut up sparse to just change it to:

	fd = sys_open((const char __user *) path, 0, 0);

Thanks,
  Roland
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