From: Oliver Hartkopp <socketcan@hartkopp•net>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: David Miller <davem@davemloft•net>,
Linux Netdev List <netdev@vger•kernel.org>,
Kurt Van Dijck <kurt.van.dijck@eia•be>,
Urs Thuermann <urs@isnogud•escape.de>
Subject: Re: [RFC net-next-2.6] can: replace spinlocks with mutexes
Date: Wed, 20 Apr 2011 18:18:40 +0200 [thread overview]
Message-ID: <4DAF0760.6000904@hartkopp.net> (raw)
In-Reply-To: <1303313954.3186.117.camel@edumazet-laptop>
On 20.04.2011 17:39, Eric Dumazet wrote:
> Le mercredi 20 avril 2011 à 17:31 +0200, Oliver Hartkopp a écrit :
>> This patch removes spinlocks for the CAN netdevice specific receive lists.
>> The RCU-based receive lists can be modified from process context or from the
>> netdevice notifier call. As both might sleep we can safely replace the
>> spinlocks with mutexes.
>>
>> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp•net>
>>
>> ---
>
> But... why ?
>
> A spinlock is faster/smaller than a mutex.
Hm, i expected the mutex to have some advantages especially in multicore
systems ...
But if it doesn't has any vital advantage, we can leave it as-is.
> Maybe you wanted to _remove_ spinlock, since/if writer hold RTNL and
> doesnt need to exclude another writer(s) ?
That's an interesting idea. The filters are modified at socket
creation/removal time and can also be modified in between using sockopts by
_ordinary_ users. Could that be a problem?
> Note : I did not check the RTNL assertion, you might add appropriate
> ASSERT_RTNL() calls just to be 100% safe.
I'll investigate some similar places in the networking code and then replace
the spinlocks with rtnl_locks for some testing.
Thanks for the feedback,
Oliver
next prev parent reply other threads:[~2011-04-20 16:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-20 15:31 [RFC net-next-2.6] can: replace spinlocks with mutexes Oliver Hartkopp
2011-04-20 15:39 ` Eric Dumazet
2011-04-20 16:18 ` Oliver Hartkopp [this message]
2011-04-21 13:00 ` Oliver Hartkopp
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