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Subject: Re: [PATCH v3] usb: dwc3: gadget: Prevent EP queuing while stopping
 transfers
To:     Andy Shevchenko <andy.shevchenko@gmail.com>
Cc:     Felipe Balbi <balbi@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        USB <linux-usb@vger.kernel.org>
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From:   Wesley Cheng <wcheng@codeaurora.org>
Message-ID: <eb91f1dc-d9ae-136d-4074-f1f70d666064@codeaurora.org>
Date:   Tue, 23 Mar 2021 14:53:10 -0700
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On 3/23/2021 10:27 AM, Andy Shevchenko wrote:
> On Tue, Mar 23, 2021 at 1:19 AM Wesley Cheng <wcheng@codeaurora.org> wrote:
>>
>> Hi Andy,
>>
>> On 3/22/2021 2:14 PM, Andy Shevchenko wrote:
>>> On Mon, Mar 22, 2021 at 10:06 PM Wesley Cheng <wcheng@codeaurora.org> wrote:
>>>>
>>>> Hi Andy,
>>>>
>>>> On 3/22/2021 12:34 PM, Andy Shevchenko wrote:
>>>>> On Mon, Mar 22, 2021 at 8:49 PM Wesley Cheng <wcheng@codeaurora.org> wrote:
>>>>>>
>>>>>> Hi Andy,
>>>>>>
>>>>>> On 3/22/2021 5:48 AM, Andy Shevchenko wrote:
>>>>>>> On Fri, Mar 12, 2021 at 2:01 AM Wesley Cheng <wcheng@codeaurora.org> wrote:
>>>>>>>>
>>>>>>>> In the situations where the DWC3 gadget stops active transfers, once
>>>>>>>> calling the dwc3_gadget_giveback(), there is a chance where a function
>>>>>>>> driver can queue a new USB request in between the time where the dwc3
>>>>>>>> lock has been released and re-aquired.  This occurs after we've already
>>>>>>>> issued an ENDXFER command.  When the stop active transfers continues
>>>>>>>> to remove USB requests from all dep lists, the newly added request will
>>>>>>>> also be removed, while controller still has an active TRB for it.
>>>>>>>> This can lead to the controller accessing an unmapped memory address.
>>>>>>>>
>>>>>>>> Fix this by ensuring parameters to prevent EP queuing are set before
>>>>>>>> calling the stop active transfers API.
>>>>>>>
>>>>>>>
>>>>>>> commit f09ddcfcb8c569675066337adac2ac205113471f
>>>>>>> Author: Wesley Cheng <wcheng@codeaurora.org>
>>>>>>> Date:   Thu Mar 11 15:59:02 2021 -0800
>>>>>>>
>>>>>>>    usb: dwc3: gadget: Prevent EP queuing while stopping transfers
>>>>>>>
>>>>>>> effectively broke my gadget setup.
>>>>>>>
>>>>>>> The output of the kernel (followed by non responsive state of USB controller):
>>>>>>>
>>>>>>> [  195.228586] using random self ethernet address
>>>>>>> [  195.233104] using random host ethernet address
>>>>>>> [  195.245306] usb0: HOST MAC aa:bb:cc:dd:ee:f2
>>>>>>> [  195.249732] usb0: MAC aa:bb:cc:dd:ee:f1
>>>>>>> # [  195.773594] IPv6: ADDRCONF(NETDEV_CHANGE): usb0: link becomes ready
>>>>>>> [  195.780585] ------------[ cut here ]------------
>>>>>>> [  195.785217] dwc3 dwc3.0.auto: No resource for ep2in
>>>>>>> [  195.790162] WARNING: CPU: 0 PID: 217 at
>>>>>>> drivers/usb/dwc3/gadget.c:360 dwc3_send_gadget_ep_cmd+0x4b9/0x670
>>>>>>> [  195.799760] Modules linked in: usb_f_eem u_ether libcomposite
>>>>>>> brcmfmac brcmutil mmc_block pwm_lpss_pci pwm_lps
>>>>>>> s snd_sof_pci_intel_tng snd_sof_pci snd_sof_acpi_intel_byt
>>>>>>> snd_sof_intel_ipc snd_sof_acpi snd_sof snd_sof_nocodec
>>>>>>> spi_pxa2xx_platform snd_sof_xtensa_dsp spi_pxa2xx_pci
>>>>>>> extcon_intel_mrfld intel_mrfld_adc sdhci_pci cqhci sdhci m
>>>>>>> mc_core intel_mrfld_pwrbtn intel_soc_pmic_mrfld hci_uart btbcm btintel
>>>>>>> [  195.835604] CPU: 0 PID: 217 Comm: irq/16-dwc3 Not tainted 5.12.0-rc4+ #60
>>>>>>> [  195.842403] Hardware name: Intel Corporation Merrifield/BODEGA BAY,
>>>>>>> BIOS 542 2015.01.21:18.19.48
>>>>>>> [  195.851191] RIP: 0010:dwc3_send_gadget_ep_cmd+0x4b9/0x670
>>>>>>> [  195.856608] Code: cd 00 00 00 44 89 44 24 20 48 89 4c 24 18 e8 ee
>>>>>>> f7 e4 ff 48 8b 4c 24 18 4c 89 f2 48 c7 c7 b9
>>>>>>> ed 4f a0 48 89 c6 e8 ef 24 43 00 <0f> 0b 41 be ea ff ff ff 44 8b 44 24
>>>>>>> 20 e9 80 fc ff ff 41 83 fe 92
>>>>>>> [  195.875381] RSP: 0000:ffffa53c00373ba8 EFLAGS: 00010086
>>>>>>> [  195.880617] RAX: 0000000000000000 RBX: 0000000000001387 RCX: 00000000ffffdfff
>>>>>>> [  195.887755] RDX: 00000000ffffdfff RSI: 00000000ffffffea RDI: 0000000000000000
>>>>>>> [  195.894893] RBP: ffff9ce8c8f2b028 R08: ffffffffa0732288 R09: 0000000000009ffb
>>>>>>> [  195.902034] R10: 00000000ffffe000 R11: 3fffffffffffffff R12: 0000000000041006
>>>>>>> [  195.909170] R13: ffffa53c00373c24 R14: ffff9ce8c11dadb0 R15: ffff9ce8c2861700
>>>>>>> [  195.916310] FS:  0000000000000000(0000) GS:ffff9ce8fe200000(0000)
>>>>>>> knlGS:0000000000000000
>>>>>>> [  195.924409] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>>>>> [  195.930161] CR2: 00000000f7f694a0 CR3: 0000000038e0c000 CR4: 00000000001006f0
>>>>>>> [  195.937300] Call Trace:
>>>>>>> [  195.939755]  __dwc3_gadget_ep_enable+0x2d4/0x4e0
>>>>>>> [  195.944393]  ? dwc3_remove_requests.constprop.0+0x86/0x170
>>>>>>
>>>>>> Odd that this change would affect the USB enablment path, as they were
>>>>>> focused on the pullup disable path.  Would you happen to have any
>>>>>> downstream changes on top of v5.12-rc4 we could review to see if they
>>>>>> are still required? (ie where is the dwc3_remove_requests() coming from
>>>>>> during ep enable)
>>>>>
>>>>> You may check my branch [1] on GH. Basically you may be interested in
>>>>> the commit:
>>>>> 0f86df1294ee7523060cc16eafaf4898c693eab0 REVERTME: usb: dwc3: gadget:
>>>>> skip endpoints ep[18]{in,out}
>>>>> Otherwise it's a clean v5.12-rc4 with a revert and another USB PHY
>>>>> suspend fix (which also shouldn't affect this).
>>>>
>>>> Can you link your GH reference?
>>>
>>> Oops, sorry.
>>> Here we are:
>>>
>>> [1]: https://github.com/andy-shev/linux/tree/eds-acpi
>>>
>> Thanks, I took a look and even tried it on my device running 5.12-rc4,
>> but wasn't able to see the same problem.  Could you help collect the
>> ftrace after enabling the tracing KCONFIG and running the below sequence?
>>
>> 1.  Mount debugfs
>> 2.  Set up tracing instance
>>
>> mkdir /sys/kernel/debug/tracing/instances/usb
>> echo 1 >
>> /sys/kernel/debug/tracing/instances/usb/events/dwc3/dwc3_complete_trb/enable
>> echo 1 >
>> /sys/kernel/debug/tracing/instances/usb/events/dwc3/dwc3_ctrl_req/enable
>> echo 1 >
>> /sys/kernel/debug/tracing/instances/usb/events/dwc3/dwc3_ep_dequeue/enable
>> echo 1 >
>> /sys/kernel/debug/tracing/instances/usb/events/dwc3/dwc3_ep_queue/enable
>> echo 1 >
>> /sys/kernel/debug/tracing/instances/usb/events/dwc3/dwc3_gadget_ep_cmd/enable
>> echo 1 >
>> /sys/kernel/debug/tracing/instances/usb/events/dwc3/dwc3_gadget_ep_disable/enable
>> echo 1 >
>> /sys/kernel/debug/tracing/instances/usb/events/dwc3/dwc3_gadget_ep_enable/enable
>> echo 1 >
>> /sys/kernel/debug/tracing/instances/usb/events/dwc3/dwc3_gadget_giveback/enable
>> echo 1 >
>> /sys/kernel/debug/tracing/instances/usb/events/dwc3/dwc3_prepare_trb/enable
>> echo 1 > /sys/kernel/debug/tracing/instances/usb/tracing_on
>>
>> 3.  Run your test, which should include:
>>         - echo "" > /sys/kernel/config/usb_gadget/g1/UDC
>>         - echo <UDC name> > /sys/kernel/config/usb_gadget/g1/UDC
>>
>> 4.  Collect the trace output:
>> cat /sys/kernel/debug/tracing/instances/usb/trace
> 
> Here we are (I cherry-picked again reverted patch, other stays the same) [2].
> On top I put a warning, so you may see timestamps.
> 
> Dunno how long it will stay there, please confirm that you got it.
> 
> [2]: https://paste.ubuntu.com/p/jNF565ypPp/
> 

Hi Andy,

Would you be able to give the below change a try?

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 80606b8..cd58bd5 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -791,10 +791,6 @@ static int __dwc3_gadget_ep_disable(struct dwc3_ep
*dep)
     reg &= ~DWC3_DALEPENA_EP(dep->number);
     dwc3_writel(dwc->regs, DWC3_DALEPENA, reg);

-    dep->stream_capable = false;
-    dep->type = 0;
-    dep->flags = 0;
-
     /* Clear out the ep descriptors for non-ep0 */
     if (dep->number > 1) {
         dep->endpoint.comp_desc = NULL;
@@ -803,6 +799,10 @@ static int __dwc3_gadget_ep_disable(struct dwc3_ep
*dep)

     dwc3_remove_requests(dwc, dep);

+    dep->stream_capable = false;
+    dep->type = 0;
+    dep->flags = 0;
+
     return 0;
 }

Thanks
Wesley Cheng

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