From: "Chris Friesen" <cfriesen@nortel.com>
To: LKML <linux-kernel@vger.kernel.org>
Subject: question on type conversions in show_map_vma()
Date: Wed, 02 Dec 2009 12:34:21 -0600 [thread overview]
Message-ID: <4B16B32D.9030106@nortel.com> (raw)
Another developer and I were looking at show_map_vma() and started
wondering about the "pgoff" value:
pgoff = ((loff_t)vma->vm_pgoff) << PAGE_SHIFT;
Here we take a variable of type "unsigned long", we cast it to "long
long", shift it, then assign the result to a variable of type "unsigned
long long".
I realize that there isn't any danger of invalid sign extension, but it
does seem a bit odd to be casting to a signed value when the result is
going to be unsigned.
Is there a historical reason why pgoff is unsigned rather than just of
type "loff_t"?
Chris
reply other threads:[~2009-12-02 18:36 UTC|newest]
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