From: Casey Leedom <leedom@chelsio.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: David Miller <davem@davemloft.net>,
rongqing.li@windriver.com, netdev@vger.kernel.org,
hariprasad@chelsio.com, greearb@candelatech.com
Subject: Re: [PATCH][RFC] cxgb4: Not need to hold the adap_rcu_lock lock when read adap_rcu_list
Date: Tue, 24 Jun 2014 09:42:10 -0700 [thread overview]
Message-ID: <53A9AA62.7070503@chelsio.com> (raw)
In-Reply-To: <1403591903.27425.4.camel@edumazet-glaptop2.roam.corp.google.com>
Okay, so it looks like everyone is happy with Li's patch. So I think
I'm supposed to say:
Acked-by: Casey Leedom <leedom@chelsio.com>
Casey
On 06/23/14 23:38, Eric Dumazet wrote:
> On Mon, 2014-06-23 at 15:35 -0700, Casey Leedom wrote:
>> On 06/23/14 14:50, David Miller wrote:
>>> From: <rongqing.li@windriver.com>
>>> Date: Fri, 20 Jun 2014 17:32:36 +0800
>>>
>>>> cxgb4_netdev maybe lead to dead lock, since it uses a spin lock, and be called
>>>> in both thread and softirq context, but not disable BH, the lockdep report is
>>>> below; In fact, cxgb4_netdev only reads adap_rcu_list with RCU protection, so
>>>> not need to hold spin lock again.
>>> I think this change is fine, and correct, but I would like to see some
>>> reviews from the cxgb4 maintainers.
>> Thanks David. Hari is gone on PTO so I think I'm the next logical
>> person ... :-)
>>
>> I've gone back and reviewed the original patch, Eric Dumazet6's reply
>> and revised patch and compared that against this proposed patch. Li
>> RongQing is submitting the same patch that Eric suggested with the
>> addition of a call to synchronize_rcu() the in driver remove()
>> function. I'm not super familiar with the RCU system but that addition
>> certainly seems innocuous enough. Other than that, everything looks fine.
> Yes, the synchronize_rcu() is needed.
>
> In fact I do not really understand why RCU was even used in this slow
> path...
>
>
>
next prev parent reply other threads:[~2014-06-24 16:42 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-20 9:32 [PATCH][RFC] cxgb4: Not need to hold the adap_rcu_lock lock when read adap_rcu_list rongqing.li
2014-06-23 21:50 ` David Miller
2014-06-23 22:35 ` Casey Leedom
2014-06-24 0:20 ` Li RongQing
2014-06-24 6:38 ` Eric Dumazet
2014-06-24 16:42 ` Casey Leedom [this message]
2014-06-24 22:54 ` David Miller
2014-06-24 22:56 ` Casey Leedom
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