linux-kernel - Re: Re: [PATCH 2/3] block: Fix not tracing all device plug-operation.

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Message-ID: <201209150935486569381@gmail.com>
Date:	Sat, 15 Sep 2012 09:35:52 +0800
From:	"Jianpeng Ma" <majianpeng@...il.com>
To:	"Jens Axboe" <jaxboe@...ionio.com>
Cc:	shli <shli@...nel.org>, linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: Re: [PATCH 2/3] block: Fix not tracing all device plug-operation.

On 2012-08-10 21:09 Jens Axboe <jaxboe@...ionio.com> Wrote:
>On 08/10/2012 01:46 PM, Jianpeng Ma wrote:
>> If process handled two or more devices,there will not be trace some
>> devices plug-operation.
>> 
>> Signed-off-by: Jianpeng Ma <majianpeng@...il.com>
>> ---
>>  block/blk-core.c |   16 +++++++++++++++-
>>  1 file changed, 15 insertions(+), 1 deletion(-)
>> 
>> diff --git a/block/blk-core.c b/block/blk-core.c
>> index 7a3abc6..034f186 100644
>> --- a/block/blk-core.c
>> +++ b/block/blk-core.c
>> @@ -1521,11 +1521,25 @@ get_rq:
>>  				struct request *__rq;
>>  
>>  				__rq = list_entry_rq(plug->list.prev);
>> -				if (__rq->q != q)
>> +				if (__rq->q != q) {
>>  					plug->should_sort = 1;
>> +					trace_block_plug(q);
>> +				}
>> +			} else {
>> +				struct request *__rq;
>> +				list_for_each_entry_reverse(__rq, &plug->list,
>> +					queuelist) {
>> +					if (__rq->q == q) {
>> +						list_add_tail(&req->queuelist,
>> +							&__rq->queuelist);
>> +						goto stat_acct;
>
>Did you verify this? It doesn't look right to me. You browse the list in
>reverse, which means __rq is the first one that has a matching q. Then
>you add the new req IN FRONT of that. You would want list_add() here
>instead, adding it as the last member of that q string, not in the
>middle.
>
>-- 
>Jens Axboe
>
Hi all:
	How about those patches? Ok or wrong? 
Thanks!