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Message-ID: <5025080A.1040001@fusionio.com>
Date: Fri, 10 Aug 2012 15:09:30 +0200
From: Jens Axboe <jaxboe@...ionio.com>
To: Jianpeng Ma <majianpeng@...il.com>
CC: shli <shli@...nel.org>, linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] block: Fix not tracing all device plug-operation.
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
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