Hi,
Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx> writes:
>>> >> Reverting that commit is not the best idea. Let's start with the usual:
>>> >>
>>> >> - Kernel version
>>> >> - dmesg on both sides (host and device)
>>> >> - dwc3 tracepoints:
>>> >>
>>> >> # mkdir -p /t
>>> >> # mount -t tracefs none /t
>>> >> # echo 8192 > /t/buffer_size_kb
>>> >> # echo 1 > /t/events/dwc3/enable
>>> >> # echo 0 > /t/events/dwc3/dwc3_readl/enable
>>> >> # echo 0 > /t/events/dwc3/dwc3_writel/enable
>>> >>
>>> >> This should be enough to tell me what's really going on.
>>> >
>>> > I've attached the (compressed due to size) dmesgs/traces from the device.
>>> > For my test I just did 'for i in `seq 1 5` ; dmesg ; done' in an ssh
>>> > session, and I did get the lag in the bad run, so presumably the trace
>>> > should have caught it. Both were on 4.8 (+ the revert for the good run).
>>> >
>>> > Host side dmesg just showes me:
>>> > usb 3-3.4: new high-speed USB device number 25 using xhci_hcd
>>> > cdc_ether 3-3.4:1.0 usb0: register 'cdc_ether' at usb-0000:00:14.0-3.4, CDC Ethernet Device, ...
>>> > when I boot the device. Nothing extra appears when things lag around.
>>> > I'm running 4.5.something on the host.
>>>
>>> Looking at your logs what I can see is that "revert.trace" doesn't
>>> respect gadget driver's IRQ throttling, which means you get an interrupt
>>> for each and every request, while "bad.trace" shows dwc3 respecting
>>> "no_interrupt" flag passed in by g_ether.
>>>
>>> The only explanation I have for this behavior when we start respecting
>>> gadget driver's flags, is that there's a possible race in u_ether.c
>>> where it can go for a long time without an interrupt due to that
>>> throttling.
>>>
>>> This only happens with IN endpoints (the ones which are throttled) and
>>> the behavior can be seen in log snippet below:
>>>
>>> 27782: irq/17-dwc3-2524 [000] d... 666.891969: tx_complete: req ffff88016da1a6c0 length 1514/1514 flags ZsI tx_qlen 4 qmult 5
>>> 27802: ksoftirqd/0-3 [000] .Ns1 666.892047: eth_start_xmit: req ffff88016da1a6c0 length 0/1514 flags Zsi tx_qlen 5 qmult 5
>>> 27808: ksoftirqd/0-3 [000] .Ns2 666.892062: eth_start_xmit: req ffff88016da1a300 length 0/1514 flags ZsI tx_qlen 6 qmult 5
>>> 27814: ksoftirqd/0-3 [000] .Ns2 666.892069: eth_start_xmit: req ffff88016da1ab40 length 0/1514 flags Zsi tx_qlen 7 qmult 5
>>> 27820: ksoftirqd/0-3 [000] .Ns2 666.892075: eth_start_xmit: req ffff88016da1acc0 length 0/1514 flags Zsi tx_qlen 8 qmult 5
>>> 27826: ksoftirqd/0-3 [000] .Ns2 666.892082: eth_start_xmit: req ffff88016da1ae40 length 0/1514 flags Zsi tx_qlen 9 qmult 5
>>> 27832: ksoftirqd/0-3 [000] .Ns2 666.892088: eth_start_xmit: req ffff88016da1a780 length 0/1514 flags Zsi tx_qlen 10 qmult 5
>>> 27884: irq/17-dwc3-2524 [000] d... 666.892213: tx_complete: req ffff88016da1a840 length 1514/1514 flags Zsi tx_qlen 9 qmult 5
>>> 27889: irq/17-dwc3-2524 [000] d... 666.892215: tx_complete: req ffff88016da1a600 length 1514/1514 flags Zsi tx_qlen 8 qmult 5
>>> 27897: sshd-2684 [002] ..s1 666.892223: eth_start_xmit: req ffff88016da1a840 length 0/1514 flags Zsi tx_qlen 9 qmult 5
>>> 27898: irq/17-dwc3-2524 [000] d... 666.892223: tx_complete: req ffff88016da1a180 length 1514/1514 flags Zsi tx_qlen 8 qmult 5
>>> 27903: irq/17-dwc3-2524 [000] d... 666.892225: tx_complete: req ffff88016da1a240 length 1514/1514 flags Zsi tx_qlen 7 qmult 5
>>> 27910: sshd-2684 [002] ..s1 666.892230: eth_start_xmit: req ffff88016da1a180 length 0/1514 flags Zsi tx_qlen 8 qmult 5
>>> 27913: irq/17-dwc3-2524 [000] d... 666.892231: tx_complete: req ffff88016da1a6c0 length 1514/1514 flags Zsi tx_qlen 7 qmult 5
>>> 27920: sshd-2684 [002] ..s1 666.892236: eth_start_xmit: req ffff88016da1a6c0 length 0/1514 flags Zsi tx_qlen 8 qmult 5
>>> 27923: irq/17-dwc3-2524 [000] d... 666.892238: tx_complete: req ffff88016da1a300 length 1514/1514 flags ZsI tx_qlen 7 qmult 5
>>> 27928: sshd-2684 [002] ..s1 666.892242: eth_start_xmit: req ffff88016da1a240 length 0/1514 flags Zsi tx_qlen 8 qmult 5
>>> 27944: sshd-2684 [002] ..s1 666.892253: eth_start_xmit: req ffff88016da1a300 length 0/1514 flags Zsi tx_qlen 9 qmult 5
>>> 27953: sshd-2684 [002] ..s1 666.892262: eth_start_xmit: req ffff88016da1a600 length 0/1514 flags Zsi tx_qlen 10 qmult 5
>>>
>>> Note here that we reached tx_qlen = 10 without any interrupts being requested.
>>>
>>> I patched u_ether with below to capture log above:
>>>
>>> diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c
>>> index 5f562c1ec795..e34c26ffcdf4 100644
>>> --- a/drivers/usb/gadget/function/u_ether.c
>>> +++ b/drivers/usb/gadget/function/u_ether.c
>>> @@ -465,6 +465,15 @@ static void tx_complete(struct usb_ep *ep, struct usb_request *req)
>>> dev_kfree_skb_any(skb);
>>>
>>> atomic_dec(&dev->tx_qlen);
>>> +
>>> + trace_printk("req %p length %d/%d flags %c%c%c tx_qlen %d qmult %d\n",
>>> + req, req->actual, req->length,
>>> + req->zero ? 'Z' : 'z',
>>> + req->short_not_ok ? 'S' : 's',
>>> + req->no_interrupt ? 'i' : 'I',
>>> + atomic_read(&dev->tx_qlen),
>>> + dev->qmult);
>>> +
>>> if (netif_carrier_ok(dev->net))
>>> netif_wake_queue(dev->net);
>>> }
>>> @@ -600,6 +609,12 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
>>> case 0:
>>> netif_trans_update(net);
>>> atomic_inc(&dev->tx_qlen);
>>> + trace_printk("req %p length %d/%d flags %c%c%c tx_qlen %d qmult %d\n",
>>> + req, req->actual, req->length, req->zero ? 'Z' : 'z',
>>> + req->short_not_ok ? 'S' : 's',
>>> + req->no_interrupt ? 'i' : 'I',
>>> + atomic_read(&dev->tx_qlen),
>>> + dev->qmult);
>>> }
>>>
>>> if (retval) {
>>>
>>> The only way I can think of to avoid this problem is to make sure we
>>> don't starve our request queue with something like:
>>>
>>> diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c
>>> index 5f562c1ec795..ddfa866c2cba 100644
>>> --- a/drivers/usb/gadget/function/u_ether.c
>>> +++ b/drivers/usb/gadget/function/u_ether.c
>>> @@ -587,8 +596,9 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb,
>>>
>>> /* throttle high/super speed IRQ rate back slightly */
>>> if (gadget_is_dualspeed(dev->gadget))
>>> - req->no_interrupt = (dev->gadget->speed == USB_SPEED_HIGH ||
>>> - dev->gadget->speed == USB_SPEED_SUPER)
>>> + req->no_interrupt = (((dev->gadget->speed == USB_SPEED_HIGH ||
>>> + dev->gadget->speed == USB_SPEED_SUPER)) &&
>>> + !list_empty(&dev->tx_reqs))
>>> ? ((atomic_read(&dev->tx_qlen) % dev->qmult) != 0)
>>> : 0;
>>>
>>> I have been testing this for about half an hour and I can't see delays
>>> or link getting stuck. Care to test ? If it works for your setup, I'll
>>> send this with Cc: stable and your Reported-by and Tested-by tags.
>>
>> That doesn't appear to cure the problem unfortunately. I've attached another
>> trace, with your u_ether trace_printks included.
>
> Now I only seem to find delays on ep1out. Here are a few instances:
>
> irq/22-dwc3-803 [001] d..1 19.446979: dwc3_gadget_ep_cmd: ep1out: cmd 'Update Transfer' [131079] params 00000000 00000000 00000000 --> status: Successful
> irq/22-dwc3-803 [001] d..1 20.452232: dwc3_event: event (00006084): ep1out: Transfer In-Progress
>
> irq/22-dwc3-803 [001] d..1 20.761702: dwc3_gadget_ep_cmd: ep1out: cmd 'Update Transfer' [131079] params 00000000 00000000 00000000 --> status: Successful
> irq/22-dwc3-803 [001] d..1 21.044345: dwc3_event: event (00006084): ep1out: Transfer In-Progress
>
> irq/22-dwc3-803 [001] d..1 21.999383: dwc3_gadget_ep_cmd: ep1out: cmd 'Update Transfer' [131079] params 00000000 00000000 00000000 --> status: Successful
> [...]
> irq/22-dwc3-803 [001] d..1 22.239576: dwc3_event: event (00006084): ep1out: Transfer In-Progress
>
> irq/22-dwc3-803 [001] d..1 22.979703: dwc3_gadget_ep_cmd: ep1out: cmd 'Update Transfer' [131079] params 00000000 00000000 00000000 --> status: Successful
> [...]
> irq/22-dwc3-803 [001] d..1 23.125096: dwc3_event: event (00006084): ep1out: Transfer In-Progress
>
> irq/22-dwc3-803 [001] d..1 23.820697: dwc3_gadget_ep_cmd: ep1out: cmd 'Update Transfer' [131079] params 00000000 00000000 00000000 --> status: Successful
> irq/22-dwc3-803 [001] d..1 24.461117: dwc3_event: event (00006084): ep1out: Transfer In-Progress
>
> irq/22-dwc3-803 [001] d..1 24.882567: dwc3_gadget_ep_cmd: ep1out: cmd 'Update Transfer' [131079] params 00000000 00000000 00000000 --> status: Successful
> irq/22-dwc3-803 [001] d..1 25.693330: dwc3_event: event (00006084): ep1out: Transfer In-Progress
>
> irq/22-dwc3-803 [001] d..1 25.702107: dwc3_gadget_ep_cmd: ep1out: cmd 'Update Transfer' [131079] params 00000000 00000000 00000000 --> status: Successful
> irq/22-dwc3-803 [001] d..1 26.045495: dwc3_event: event (00006084): ep1out: Transfer In-Progress
>
> Based on this, it would seem that host side isn't sending the data; but
> that's quite odd. Let's put a sniffer here tomorrow and look at this
> more carefully, I couldn't reproduce this with SKL as I was testing this
> today.
Okay, I have found a regression on dwc3 and another patch follows:
commit 5e1a2af3e46248c55098cdae643c4141851b703e
Author: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Date: Wed Oct 5 14:24:37 2016 +0300
usb: dwc3: gadget: properly account queued requests
Some requests could be accounted for multiple
times. Let's fix that so each and every requests is
accounted for only once.
Cc: <stable@xxxxxxxxxxxxxxx> # v4.8
Fixes: 55a0237f8f47 ("usb: dwc3: gadget: use allocated/queued reqs for LST bit")
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 07cc8929f271..3c3ced128c77 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -783,6 +783,7 @@ static void dwc3_prepare_one_trb(struct dwc3_ep *dep,
req->trb = trb;
req->trb_dma = dwc3_trb_dma_offset(dep, trb);
req->first_trb_index = dep->trb_enqueue;
+ dep->queued_requests++;
}
dwc3_ep_inc_enq(dep);
@@ -833,8 +834,6 @@ static void dwc3_prepare_one_trb(struct dwc3_ep *dep,
trb->ctrl |= DWC3_TRB_CTRL_HWO;
- dep->queued_requests++;
-
trace_dwc3_prepare_trb(dep, trb);
}
@@ -1861,8 +1860,11 @@ static int __dwc3_cleanup_done_trbs(struct dwc3 *dwc, struct dwc3_ep *dep,
unsigned int s_pkt = 0;
unsigned int trb_status;
- dep->queued_requests--;
dwc3_ep_inc_deq(dep);
+
+ if (req->trb == trb)
+ dep->queued_requests--;
+
trace_dwc3_complete_trb(dep, trb);
/*
I have also built a branch which you can use for testing. Here's a pull
request, once you tell me it works for you, then I can send proper
patches out:
The following changes since commit c8d2bc9bc39ebea8437fd974fdbc21847bb897a3:
Linux 4.8 (2016-10-02 16:24:33 -0700)
are available in the git repository at:
git://git.kernel.org/pub/scm/linux/kernel/git/balbi/usb.git tmp-test-v4.8
for you to fetch changes up to c968b8d1effe64a7980802d1eef29f4e1922faca:
usb: dwc3: gadget: properly account queued requests (2016-10-06 10:16:37 +0300)
----------------------------------------------------------------
Felipe Balbi (2):
usb: gadget: function: u_ether: don't starve tx request queue
usb: dwc3: gadget: properly account queued requests
drivers/usb/dwc3/gadget.c | 7 ++++---
drivers/usb/gadget/function/u_ether.c | 5 +++--
2 files changed, 7 insertions(+), 5 deletions(-)
--
balbi
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