Date:   Mon, 22 Mar 2021 13:06:13 -0700
From:   Wesley Cheng <wcheng@...eaurora.org>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        USB <linux-usb@...r.kernel.org>
Subject: Re: [PATCH v3] usb: dwc3: gadget: Prevent EP queuing while stopping
 transfers

Hi Andy,

On 3/22/2021 12:34 PM, Andy Shevchenko wrote:
> On Mon, Mar 22, 2021 at 8:49 PM Wesley Cheng <wcheng@...eaurora.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@...eaurora.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@...eaurora.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?

> 
> But I don't believe it should have affected this.
> 
>>> [  195.949897]  dwc3_gadget_ep_enable+0x5d/0x120
>>> [  195.954274]  usb_ep_enable+0x27/0x80
>>> [  195.957869]  gether_connect+0x32/0x1f0 [u_ether]
>>> [  195.962512]  eem_set_alt+0x6d/0x140 [usb_f_eem]
>>> [  195.967061]  composite_setup+0x224/0x1ba0 [libcomposite]
>>> [  195.972405]  ? debug_dma_unmap_page+0x79/0x80
>>> [  195.976782]  ? configfs_composite_setup+0x6b/0x90 [libcomposite]
>>> [  195.982811]  configfs_composite_setup+0x6b/0x90 [libcomposite]
>>> [  195.988668]  dwc3_ep0_interrupt+0x459/0xa50
>>> [  195.992869]  dwc3_thread_interrupt+0x8e2/0xee0
>>> [  195.997327]  ? __schedule+0x237/0x6d0
>>> [  196.001005]  ? disable_irq_nosync+0x10/0x10
>>> [  196.005200]  irq_thread_fn+0x1b/0x60
>>> [  196.008789]  irq_thread+0xd6/0x170
>>> [  196.012202]  ? irq_thread_check_affinity+0x70/0x70
>>> [  196.017004]  ? irq_forced_thread_fn+0x70/0x70
>>> [  196.021373]  kthread+0x116/0x130
>>> [  196.024617]  ? kthread_create_worker_on_cpu+0x60/0x60
>>> [  196.029680]  ret_from_fork+0x22/0x30
>>> [  196.033272] ---[ end trace 8dd104a950d8d248 ]---
>>>
>>>
>> Also, as I mentioned above, the changes should affect the pullup disable
>> path, so when you 'echo "" > UDC' or something similar to that
>> operation, did you see any errors?
> 
> After your patch I see a warning as above. Before — no errors or warnings.
> 
>> Can you provide a ftrace output w/
>> the DWC3 tracing enabled once removing the UDC?
> 
> Can you provide step-by-step instructions what should I do?
> 
Let me try with your kernel, and steps below first.

Thanks
Wesley Cheng

>>> Revert helps (I'm on v5.12-rc4 now with a revert).
>>>
>>> The script to enable gadget:
>>>
>>> #!/bin/sh -efu
>>>
>>> # Mounting CONFIGFS
>>> grep -q -w /sys/kernel/config /proc/mounts || mount -t configfs none
>>> /sys/kernel/config
>>>
>>> # Addresses and files
>>> readonly GADGET_BASE_DIR="/sys/kernel/config/usb_gadget/g1"
>>> readonly DEV_ETH_ADDR="aa:bb:cc:dd:ee:f1"
>>> readonly HOST_ETH_ADDR="aa:bb:cc:dd:ee:f2"
>>> readonly USBDISK="/usbdisk.img"
>>>
>>> # Insert modules
>>> modprobe libcomposite
>>>
>>> # Create directory structure
>>> mkdir "${GADGET_BASE_DIR}"
>>> cd "${GADGET_BASE_DIR}"
>>> mkdir -p configs/c.1/strings/0x409
>>> mkdir -p strings/0x409
>>>
>>> # Ethernet device
>>> mkdir functions/eem.usb0
>>> echo "${DEV_ETH_ADDR}" > functions/eem.usb0/dev_addr
>>> echo "${HOST_ETH_ADDR}" > functions/eem.usb0/host_addr
>>> ln -s functions/eem.usb0 configs/c.1/
>>>
>>> # Composite Gadget Setup
>>> echo 0x1d6b > idVendor          # Linux Foundation
>>> echo 0x0104 > idProduct         # Multifunction Composite Gadget
>>> echo 0x0100 > bcdDevice         # v1.0.0
>>> echo 0x0200 > bcdUSB            # USB2
>>> echo "0123456789abcdef" > strings/0x409/serialnumber
>>> echo "USBArmory"        > strings/0x409/manufacturer
>>> echo "USBArmory Gadget" > strings/0x409/product
>>> echo "Conf1"            > configs/c.1/strings/0x409/configuration
>>> echo 120                > configs/c.1/MaxPower
>>>
>>> # Activate gadgets
>>> echo dwc3.0.auto > UDC
>>>
>>> Please, tell me how to fix this, otherwise I will have to send a revert.
>>>
>> This also fixes a potential SMMU fault on targets with that enabled.  It
>> causes the controller to access a stale TRB DMA address after it has
>> already been unmapped.  I think we should figure out what is causing the
>> issue on your set up instead of reverting the entire change.
> 
> If we find a cause and have a fix during this week, otherwise it's
> rc5:ish timing when we may not have more time to play.
> 

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