From: Nick Piggin <nickpiggin@yahoo.com.au>
To: David Howells <dhowells@redhat.com>
Cc: torvalds@osdl.org, akpm@osdl.org, keyrings@linux-nfs.org,
linux-kernel@vger.kernel.org,
"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH] Keys: Improve usage of memory barriers and remove IRQ disablement
Date: Tue, 04 Apr 2006 20:58:39 +1000 [thread overview]
Message-ID: <4432515F.4030108@yahoo.com.au> (raw)
In-Reply-To: <20060404095529.31311.3892.stgit@warthog.cambridge.redhat.com>
David Howells wrote:
> diff --git a/security/keys/key.c b/security/keys/key.c
> index 99781b7..d8a6e00 100644
> --- a/security/keys/key.c
> +++ b/security/keys/key.c
> @@ -619,6 +619,7 @@ void key_put(struct key *key)
> if (key) {
> key_check(key);
>
> + smp_mb__before_atomic_dec();
> if (atomic_dec_and_test(&key->usage))
> schedule_work(&key_cleanup_task);
Shouldn't be needed: Documentation/atomic_ops.txt specifies that any atomic_
which both modifies its atomic operand and returns something is to be a full
barrier before and after the operation.
This misuse occurs a few times in core code, which makes it a bit confusing.
However, I think it is nice to add a comment if these implicit barriers are
used, if the purpose is not really obvious.
--
SUSE Labs, Novell Inc.
Send instant messages to your online friends http://au.messenger.yahoo.com
next prev parent reply other threads:[~2006-04-05 4:38 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-04 9:55 [PATCH] Keys: Improve usage of memory barriers and remove IRQ disablement David Howells
2006-04-04 10:23 ` [Keyrings] " David Howells
2006-04-04 10:58 ` Nick Piggin [this message]
2006-04-05 8:46 ` David Howells
2006-04-05 9:23 ` Nick Piggin
2006-04-05 22:51 ` David S. Miller
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