From: Keir Fraser <keir@xensource.com>
To: Kieran Mansley <kmansley@solarflare.com>,
Keir Fraser <keir@xensource.com>
Cc: <muli@il.ibm.com>, <netdev@vger.kernel.org>,
<xen-devel@lists.xensource.com>,
Stephen Hemminger <shemminger@linux-foundation.org>,
<herbert@gondor.apana.org.au>
Subject: Re: [Xen-devel] Re: [PATCH 3/4] [Net] Support Xen accelerated network plugin modules
Date: Tue, 22 May 2007 15:07:09 +0100 [thread overview]
Message-ID: <C278B79D.F53F%keir@xensource.com> (raw)
In-Reply-To: <1179837868.28562.22.camel@moonstone.uk.level5networks.com>
On 22/5/07 13:44, "Kieran Mansley" <kmansley@solarflare.com> wrote:
>> Eagerly zap the function pointers, then wait one RCU period so every CPU
>> goes through a quiescent point before unloading the module?
>>
>> -- Keir
>
> Am I right in thinking that if one of the functions that was protected
> by RCU was to block, that would be a bad thing? Clearly the data path
> hooks can't/don't block, but I'm not sure it's so obvious for things
> like probing a new device.
Are there still module reference counts? If so, functions which may block
can manipulate their module's reference count.
Or if not, I guess the accelerator module can have a private reference count
checked by whatever unload function gets called from the RCU subsystem. So
that unload becomes deferred until *both* an RCU phase has passed *and* a
reference count has fallen to zero.
-- Keir
next prev parent reply other threads:[~2007-05-22 14:07 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-18 13:16 [PATCH 3/4] [Net] Support Xen accelerated network plugin modules Kieran Mansley
2007-05-21 17:50 ` Stephen Hemminger
2007-05-22 7:00 ` Kieran Mansley
2007-05-21 17:52 ` Stephen Hemminger
2007-05-22 7:15 ` Kieran Mansley
2007-05-22 7:28 ` Kieran Mansley
2007-05-22 7:48 ` [Xen-devel] " Keir Fraser
2007-05-22 7:59 ` Kieran Mansley
2007-05-22 12:44 ` Kieran Mansley
2007-05-22 14:07 ` Keir Fraser [this message]
2007-05-22 14:20 ` Kieran Mansley
2007-05-22 15:05 ` Stephen Hemminger
2007-05-22 16:06 ` Kieran Mansley
2007-05-25 6:53 ` Andi Kleen
2007-05-21 17:54 ` Stephen Hemminger
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