From: Al Viro <viro@ZenIV.linux.org.uk>
To: David Howells <dhowells@redhat.com>
Cc: linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [RFC] get_write_access()/deny_write_access() without inode->i_lock
Date: Mon, 20 Jun 2011 14:18:18 +0100 [thread overview]
Message-ID: <20110620131818.GR11521@ZenIV.linux.org.uk> (raw)
In-Reply-To: <21839.1308574037@redhat.com>
On Mon, Jun 20, 2011 at 01:47:17PM +0100, David Howells wrote:
> Al Viro <viro@ZenIV.linux.org.uk> wrote:
>
> > + for (v = atomic_read(&inode->i_writecount); v >= 0; v = v1) {
> > + v1 = atomic_cmpxchg(&inode->i_writecount, v, v + 1);
> > + if (likely(v1 == v))
> > + return 0;
> > + }
>
> You don't need to reissue the atomic_read(). atomic_cmpxchg() returns the
> current value of the memory location. Just set v to v1 before going round the
> loop again.
That's precisely what that loop is doing...
next prev parent reply other threads:[~2011-06-20 13:18 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-19 23:51 [RFC] get_write_access()/deny_write_access() without inode->i_lock Al Viro
2011-06-20 12:47 ` David Howells
2011-06-20 13:18 ` Al Viro [this message]
2011-06-20 13:20 ` David Howells
2011-06-20 13:20 ` David Howells
2011-06-20 13:21 ` Frantisek Hrbata
2011-06-20 14:15 ` Al Viro
2011-06-20 15:55 ` Linus Torvalds
2011-06-20 15:55 ` Linus Torvalds
2011-06-20 16:13 ` Al Viro
2011-06-20 16:22 ` Linus Torvalds
2011-06-20 16:42 ` Al Viro
2011-06-20 17:03 ` Al Viro
2011-06-20 19:47 ` Andi Kleen
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