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[v2,0/2] Fix ep command fail issue in dequeue

Message ID 1644836933-141376-1-git-send-email-dh10.jung@samsung.com
Headers show
Series Fix ep command fail issue in dequeue | expand

Message

Jung Daehwan Feb. 14, 2022, 11:08 a.m. UTC 
It always sets DWC3_EP_END_TRANSFER_PENDING in dwc3_stop_active_transfer
even if dwc3_send_gadget_ep_cmd fails. It can cause some problems like
skipping clear stall commmand or giveback from dequeue. It could cause
hung task if ENDTRANSFER command should not be completed. It seems
like HW(Controller) issue but SW can prevent it.

Changes in v2:
- fix coding rule

Daehwan Jung (2):
  usb: dwc3: Not set DWC3_EP_END_TRANSFER_PENDING in ep cmd fails
  usb: dwc3: Prevent cleanup cancelled requests at the same time.

 drivers/usb/dwc3/gadget.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

Comments

Greg KH Feb. 14, 2022, 11:30 a.m. UTC | #1 
On Mon, Feb 14, 2022 at 08:08:53PM +0900, Daehwan Jung wrote:
> We added cleanup cancelled requests when ep cmd timeout on ep dequeue
> because there's no complete interrupt then. But, we find out new case
> that complete interrupt comes up later. list_for_each_entry_safe is
> used when cleanup cancelled requests and it has vulnerabilty on multi-core
> environment. dwc3_gadget_giveback unlocks dwc->lock temporarily and other
> core(ISR) can get lock and try to cleanup them again. It could cause
> list_del corruption and we use DWC3_EP_END_TRANSFER_PENDING to prevent it.
> 
> 1. MTP server cancels -> ep dequeue -> ep cmd timeout(END_TRANSFER)
> 	-> cleanup cancelled requests -> dwc3_gadget_giveback ->
> 	list_del -> release lock temporarily
> 2. Complete with END_TRANSFER -> ISR(dwc3_gadget_endpoint_command_complete)
> 	gets lock -> cleanup cancelled requests -> dwc3_gadget_giveback
> 	-> list_del
> 3. MTP server process gets lock again
> 	-> tries to access POISON list(list_del corruption)
> 
> [2: MtpServer: 5032] dwc3 10b00000.dwc3: request cancelled
> 						with wrong reason:5
> [2: MtpServer: 5032] list_del corruption,
> 		ffffff88b6963968->next is LIST_POISON1 (dead000000000100)
> 
> Signed-off-by: Daehwan Jung <dh10.jung@samsung.com>
> ---
>  drivers/usb/dwc3/gadget.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)

What commit id does this fix?

thanks,

greg k-h