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Re: [Qemu-devel] [PATCH for-2.4 06/12] etsec: Flush queue when rx buffer
From: |
Jason Wang |
Subject: |
Re: [Qemu-devel] [PATCH for-2.4 06/12] etsec: Flush queue when rx buffer is consumed |
Date: |
Wed, 15 Jul 2015 13:10:57 +0800 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 |
On 07/14/2015 05:48 PM, Fam Zheng wrote:
> On Tue, 07/14 17:33, Jason Wang wrote:
>>
>> On 07/14/2015 03:53 PM, Fam Zheng wrote:
>>> The BH will be scheduled when etsec->rx_buffer_len is becoming 0, which
>>> is the condition of queuing.
>>>
>>> Signed-off-by: Fam Zheng <address@hidden>
>> I suggest to squash this into patch 05/12 to unbreak bisection.
> 05/12 didn't change the logic, it just moved the semantics from returning 0 in
> .can_receive() to .receive(). So I think it's OK to split to make reviewing
> easier.
Ok.
>
>> And can we do this without a bh? Otherwise, we may need to stop and
>> restart the bh during vm stop and start?
> A bh doesn't hurt when vm stop and restart (we get superfluous flush),
The problem is qemu_flush_queued_packets() does not check runstate. So
it may call .receive() which may modify guest state (DMA or registers).
> otherwise the call stack could go very deap with a long queue, something like:
>
> etsec_receive
> etsec_rx_ring_write
> etsec_walk_rx_ring
> etsec_flush_rx_queue
> qemu_flush_queued_packets
> ...
> etsec_receive
> etsec_rx_ring_write
> etsec_walk_rx_ring
> etsec_flush_rx_queue
> qemu_flush_queued_packets
> /* loop */
> ...
I get the point, thanks.
>>> ---
>>> hw/net/fsl_etsec/etsec.c | 9 +++++++++
>>> hw/net/fsl_etsec/etsec.h | 2 ++
>>> hw/net/fsl_etsec/rings.c | 1 +
>>> 3 files changed, 12 insertions(+)
>>>
>>> diff --git a/hw/net/fsl_etsec/etsec.c b/hw/net/fsl_etsec/etsec.c
>>> index f5170ae..fcde9b4 100644
>>> --- a/hw/net/fsl_etsec/etsec.c
>>> +++ b/hw/net/fsl_etsec/etsec.c
>>> @@ -366,6 +366,13 @@ static NetClientInfo net_etsec_info = {
>>> .link_status_changed = etsec_set_link_status,
>>> };
>>>
>>> +static void etsec_flush_rx_queue(void *opaque)
>>> +{
>>> + eTSEC *etsec = opaque;
>>> +
>>> + qemu_flush_queued_packets(qemu_get_queue(etsec->nic));
>>> +}
>>> +
>>> static void etsec_realize(DeviceState *dev, Error **errp)
>>> {
>>> eTSEC *etsec = ETSEC_COMMON(dev);
>>> @@ -378,6 +385,8 @@ static void etsec_realize(DeviceState *dev, Error
>>> **errp)
>>> etsec->bh = qemu_bh_new(etsec_timer_hit, etsec);
>>> etsec->ptimer = ptimer_init(etsec->bh);
>>> ptimer_set_freq(etsec->ptimer, 100);
>>> +
>>> + etsec->flush_bh = qemu_bh_new(etsec_flush_rx_queue, etsec);
>>> }
>>>
>>> static void etsec_instance_init(Object *obj)
>>> diff --git a/hw/net/fsl_etsec/etsec.h b/hw/net/fsl_etsec/etsec.h
>>> index fc41773..05bb7f8 100644
>>> --- a/hw/net/fsl_etsec/etsec.h
>>> +++ b/hw/net/fsl_etsec/etsec.h
>>> @@ -144,6 +144,8 @@ typedef struct eTSEC {
>>> QEMUBH *bh;
>>> struct ptimer_state *ptimer;
>>>
>>> + QEMUBH *flush_bh;
>>> +
>>> } eTSEC;
>>>
>>> #define TYPE_ETSEC_COMMON "eTSEC"
>>> diff --git a/hw/net/fsl_etsec/rings.c b/hw/net/fsl_etsec/rings.c
>>> index a11280b..7aae93e 100644
>>> --- a/hw/net/fsl_etsec/rings.c
>>> +++ b/hw/net/fsl_etsec/rings.c
>>> @@ -646,6 +646,7 @@ void etsec_walk_rx_ring(eTSEC *etsec, int ring_nbr)
>>> } else {
>>> etsec->rx_buffer_len = 0;
>>> etsec->rx_buffer = NULL;
>>> + qemu_bh_schedule(etsec->flush_bh);
>>> }
>>>
>>> RING_DEBUG("eTSEC End of ring_write: remaining_data:%zu\n",
>>> remaining_data);
- [Qemu-devel] [PATCH for-2.4 01/12] xgmac: Drop packets with eth_can_rx is false., (continued)
- [Qemu-devel] [PATCH for-2.4 01/12] xgmac: Drop packets with eth_can_rx is false., Fam Zheng, 2015/07/14
- [Qemu-devel] [PATCH for-2.4 02/12] pcnet: Drop pcnet_can_receive, Fam Zheng, 2015/07/14
- [Qemu-devel] [PATCH for-2.4 03/12] eepro100: Drop nic_can_receive, Fam Zheng, 2015/07/14
- [Qemu-devel] [PATCH for-2.4 04/12] usbnet: Drop usbnet_can_receive, Fam Zheng, 2015/07/14
- [Qemu-devel] [PATCH for-2.4 05/12] etsec: Move etsec_can_receive into etsec_receive, Fam Zheng, 2015/07/14
- [Qemu-devel] [PATCH for-2.4 06/12] etsec: Flush queue when rx buffer is consumed, Fam Zheng, 2015/07/14
[Qemu-devel] [PATCH for-2.4 07/12] mcf_fec: Drop mcf_fec_can_receive, Fam Zheng, 2015/07/14
[Qemu-devel] [PATCH for-2.4 09/12] mipsnet: Flush queued packets when receiving is enabled, Fam Zheng, 2015/07/14
[Qemu-devel] [PATCH for-2.4 10/12] stellaris_enet: Flush queued packets when read done, Fam Zheng, 2015/07/14
[Qemu-devel] [PATCH for-2.4 11/12] dp8393x: Flush packets when link comes up, Fam Zheng, 2015/07/14
[Qemu-devel] [PATCH for-2.4 12/12] axienet: Flush queued packets when rx is done, Fam Zheng, 2015/07/14
[Qemu-devel] [PATCH for-2.4 08/12] milkymist-minimac2: Flush queued packets when link comes up, Fam Zheng, 2015/07/14