From: alfred@leakybucket.org
To: linux-kernel@vger.kernel.org
Subject: [patch] Re: 2 futex questions
Date: Tue, 24 Sep 2002 18:14:01 -0700 [thread overview]
Message-ID: <20020925011401.GA15543@closet.leakybucket.org> (raw)
In-Reply-To: <Pine.LNX.4.44.0209251015320.4690-100000@localhost.localdomain>
On Wed, Sep 25, 2002 at 10:23:16AM +0200, Ingo Molnar wrote:
>
> what it says: 'uaddr must be naturally aligned, and the word must be on a
> single page'. In theory it's possible that __alignof__(int) !=
> sizeof(int).
>
Ok, would the following actually save some cycles then?
diff -u a/kernel/futex.c b/kernel/futex.c
--- a/kernel/futex.c Tue Sep 24 15:25:01 2002
+++ b/kernel/futex.c Tue Sep 24 18:09:09 2002
@@ -321,9 +321,10 @@
pos_in_page = ((unsigned long)uaddr) % PAGE_SIZE;
- /* Must be "naturally" aligned, and not on page boundary. */
+ /* Must be "naturally" aligned, and must not cross a page boundary. */
if ((pos_in_page % __alignof__(int)) != 0
- || pos_in_page + sizeof(int) > PAGE_SIZE)
+ || ((sizeof(int) != __alignof__(int))
+ && (pos_in_page + sizeof(int) > PAGE_SIZE)))
return -EINVAL;
/* Simpler if it doesn't vanish underneath us. */
Alfred Landrum
prev parent reply other threads:[~2002-09-25 8:36 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-09-25 0:33 alfred
2002-09-25 8:23 ` Ingo Molnar
2002-09-25 1:14 ` alfred [this message]
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