linux-kernel - Re: [PATCH] direct-io: squelch maybe-uninitialized warning in do_direct

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Date:	Mon, 23 Jun 2014 12:54:08 -0700
From:	Markus Mayer <markus.mayer@...aro.org>
To:	Alexander Viro <viro@...iv.linux.org.uk>,
	Jason Cooper <jason@...edaemon.net>
CC:	Linux Filesystem Mailing List <linux-fsdevel@...r.kernel.org>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] direct-io: squelch maybe-uninitialized warning in do_direct_IO()

I did a bit of digging on this and I am wondering if the initialization
of "to" and "from" to 0 should instead be done in dio_get_page().

The warning is caused by the return in dio_get_page():

		ret = dio_refill_pages(dio, sdio);
		if (ret)
			return ERR_PTR(ret);

This code path would leave "to" and "from" uninitialized (even though the
caller currently never uses the variables in that case).

If both variables are initialized to 0 in dio_get_page(), it would
guarantee that any future callers of dio_get_page() also get to take
advantage of the initialization. If, however, the variables are only
initialized in do_direct_IO(), other callers would have to take care of
this themselves (or the same warnings will pop up there).

There aren't currently any other callers to dio_get_page(), so the
choice is probably not a terribly critical one right now, but I wanted
to at least point this out.

Regards,
-Markus
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