linux-kernel - Re: [RFC PATCH 09/11] IB/Verbs: Use management helper has_ipoib() and, cap

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Message-ID: <5515822E.2020207@profitbricks.com>
Date:	Fri, 27 Mar 2015 17:15:42 +0100
From:	Michael Wang <yun.wang@...fitbricks.com>
To:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
CC:	Roland Dreier <roland@...nel.org>,
	Sean Hefty <sean.hefty@...el.com>,
	Hal Rosenstock <hal.rosenstock@...il.com>,
	Ira Weiny <ira.weiny@...el.com>, linux-rdma@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-nfs@...r.kernel.org,
	netdev@...r.kernel.org, "J. Bruce Fields" <bfields@...ldses.org>,
	Trond Myklebust <trond.myklebust@...marydata.com>,
	"David S. Miller" <davem@...emloft.net>,
	Or Gerlitz <ogerlitz@...lanox.com>,
	Moni Shoua <monis@...lanox.com>,
	PJ Waskiewicz <pj.waskiewicz@...idfire.com>,
	Tatyana Nikolova <Tatyana.E.Nikolova@...el.com>,
	Yan Burman <yanb@...lanox.com>,
	Jack Morgenstein <jackm@....mellanox.co.il>,
	Bart Van Assche <bvanassche@....org>,
	Yann Droneaud <ydroneaud@...eya.com>,
	Colin Ian King <colin.king@...onical.com>,
	Majd Dibbiny <majd@...lanox.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Matan Barak <matanb@...lanox.com>,
	Alex Estrin <alex.estrin@...el.com>,
	Doug Ledford <dledford@...hat.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Erez Shitrit <erezsh@...lanox.com>,
	Sagi Grimberg <sagig@...lanox.com>,
	Haggai Eran <haggaie@...lanox.com>,
	Shachar Raindel <raindel@...lanox.com>,
	Mike Marciniszyn <mike.marciniszyn@...el.com>,
	Steve Wise <swise@...ngridcomputing.com>,
	Tom Tucker <tom@....us>, Chuck Lever <chuck.lever@...cle.com>
Subject: Re: [RFC PATCH 09/11] IB/Verbs: Use management helper has_ipoib()
 and, cap_ipoib() for ipoib-check

On 03/27/2015 05:06 PM, Jason Gunthorpe wrote:
> On Fri, Mar 27, 2015 at 04:48:22PM +0100, Michael Wang wrote:
>
>> diff --git a/drivers/infiniband/ulp/ipoib/ipoib_main.c b/drivers/infiniband/ulp/ipoib/ipoib_main.c
>> index 3341754..fcd7558 100644
>> +++ b/drivers/infiniband/ulp/ipoib/ipoib_main.c
>> @@ -1655,7 +1655,7 @@ static void ipoib_add_one(struct ib_device *device)
>>      struct ipoib_dev_priv *priv;
>>      int s, e, p;
>>  
>> -    if (!rdma_transport_is_ib(device))
>> +    if (!has_ipoib(device))
>>          return;
> This is a good example of a test that doesn't really make sense, IPoIB
> is certainly a port specific attribute.
According to my understanding, seems like the logical is:

    if 'device have no port need ipoib initialization'
            return
>
>>      dev_list = kmalloc(sizeof *dev_list, GFP_KERNEL);
>> @@ -1673,7 +1673,7 @@ static void ipoib_add_one(struct ib_device *device)
>>      }
>>  
>>      for (p = s; p <= e; ++p) {
>> -        if (!rdma_port_ll_is_ib(device, p))
>> +        if (!cap_ipoib(device, p))
>>              continue;
> And down here we test every port.
>
> The routine should just test every port and do nothing if no ports
> need IPoIB.
And here since there are some initial work to do, it iterate all the
port to find out which one need to be initialized.

>
>>          dev = ipoib_add_port("ib%d", device, p);
>>          if (!IS_ERR(dev)) {
>> @@ -1690,7 +1690,7 @@ static void ipoib_remove_one(struct ib_device *device)
>>      struct ipoib_dev_priv *priv, *tmp;
>>      struct list_head *dev_list;
>>  
>> -    if (!rdma_transport_is_ib(device))
>> +    if (!has_ipoib(device))
>>          return;
> This test should be made redundant by having ib_get_client_data return
> null if ipoib_add_one didn't do anything. Maybe that already happens?
Here if we have done nothing when add a device, then nothing
need to be cleanup when remove it.

I'm not sure if it's a good idea, but seems like the idea is use twice
check on different level to save some cycles?

Regards,
Michael Wang
>
> Jason

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