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Re: [Qemu-devel] qemu/xendisk: properly update stats in ioreq_release()
From: |
Jan Beulich |
Subject: |
Re: [Qemu-devel] qemu/xendisk: properly update stats in ioreq_release() |
Date: |
Mon, 14 May 2012 08:39:03 +0100 |
>>> On 11.05.12 at 18:01, Stefano Stabellini <address@hidden>
wrote:
> On Thu, 10 May 2012, Jan Beulich wrote:
>> While for the "normal" case (called from blk_send_response_all())
>> decrementing requests_finished is correct, doing so in the parse error
>> case is wrong; requests_inflight needs to be decremented instead.
>>
>> Signed-off-by: Jan Beulich <address@hidden>
>>
>> --- a/hw/xen_disk.c
>> +++ b/hw/xen_disk.c
>> @@ -154,7 +154,7 @@ static void ioreq_finish(struct ioreq *i
>> blkdev->requests_finished++;
>> }
>>
>> -static void ioreq_release(struct ioreq *ioreq)
>> +static void ioreq_release(struct ioreq *ioreq, bool finish)
>> {
>> struct XenBlkDev *blkdev = ioreq->blkdev;
>>
>> @@ -162,7 +162,10 @@ static void ioreq_release(struct ioreq *
>> memset(ioreq, 0, sizeof(*ioreq));
>> ioreq->blkdev = blkdev;
>> QLIST_INSERT_HEAD(&blkdev->freelist, ioreq, list);
>> - blkdev->requests_finished--;
>> + if (finish)
>> + blkdev->requests_finished--;
>> + else
>> + blkdev->requests_inflight--;
>> }
>>
>> /*
>> @@ -449,7 +452,7 @@ static void blk_send_response_all(struct
>> while (!QLIST_EMPTY(&blkdev->finished)) {
>> ioreq = QLIST_FIRST(&blkdev->finished);
>> send_notify += blk_send_response_one(ioreq);
>> - ioreq_release(ioreq);
>> + ioreq_release(ioreq, true);
>> }
>> if (send_notify) {
>> xen_be_send_notify(&blkdev->xendev);
>> @@ -505,7 +508,7 @@ static void blk_handle_requests(struct X
>> if (blk_send_response_one(ioreq)) {
>> xen_be_send_notify(&blkdev->xendev);
>> }
>> - ioreq_release(ioreq);
>> + ioreq_release(ioreq, false);
>> continue;
>> }
>
> In case of an error returned by ioreq_parse requests_finished should
> also be decremented.
I don't think so - it gets incremented in ioreq_finish(), and that gets
called only when I/O was at least attempted (which isn't the case
when parse failed).
Jan