From mboxrd@z Thu Jan  1 00:00:00 1970
From: Oliver Hartkopp <socketcan@hartkopp.net>
Subject: Re: [RFC net-next-2.6] can: replace spinlocks with mutexes
Date: Thu, 21 Apr 2011 15:00:45 +0200
Message-ID: <4DB02A7D.4010909@hartkopp.net>
References: <4DAEFC55.2010500@hartkopp.net> <1303313954.3186.117.camel@edumazet-laptop>
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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>
To: Eric Dumazet <eric.dumazet@gmail.com>
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On 20.04.2011 17:39, Eric Dumazet wrote:
> Le mercredi 20 avril 2011 =C3=A0 17:31 +0200, Oliver Hartkopp a =C3=A9=
crit :
>> 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 t=
he
>> spinlocks with mutexes.
>>
>> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
>>
>> ---
>=20
> But... why ?
>=20
> A spinlock is faster/smaller than a mutex.
>=20
> Maybe you wanted to _remove_ spinlock, since/if writer hold RTNL and
> doesnt need to exclude another writer(s) ?
>=20
> Note : I did not check the RTNL assertion, you might add appropriate
> ASSERT_RTNL() calls just to be 100% safe.
>=20

I played a bit with rtnl locks but ran into problems with a lock sock w=
hen
enabling all locking debug techniques. Therefore i pull back my RFC for=
 now
and leave the locking using spinlocks as-is.

Thanks,
Oliver