From: linyyuan@codeaurora.org
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Felipe Balbi <balbi@kernel.org>,
Thinh Nguyen <Thinh.Nguyen@synopsys.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
Jack Pham <jackp@codeaurora.org>
Subject: Re: [PATCH v3 1/2] usb: udc: core: hide struct usb_gadget_driver to gadget driver
Date: Sun, 20 Jun 2021 11:53:18 +0800 [thread overview]
Message-ID: <018a4e222c2c3d6f5ca63b5f2036f8d8@codeaurora.org> (raw)
In-Reply-To: <42b3ebc2316495328e2d0061af81ef17@codeaurora.org>
On 2021-06-20 11:46, linyyuan@codeaurora.org wrote:
> On 2021-06-20 10:13, Alan Stern wrote:
>> On Sat, Jun 19, 2021 at 11:43:08PM +0800, Linyu Yuan wrote:
>>> currently most gadget driver have a pointer to save
>>> struct usb_gadget_driver from upper layer,
>>> it allow upper layer set and unset of the pointer.
>>>
>>> there is race that upper layer unset the pointer first,
>>> but gadget driver use the pointer later,
>>> and it cause system crash due to NULL pointer access.
>>
>> This race has already been fixed in Greg's usb-next branch. See
>> commit
>> 7dc0c55e9f30 ("USB: UDC core: Add udc_async_callbacks gadget op") and
>> following commits 04145a03db9d ("USB: UDC: Implement
>> udc_async_callbacks in dummy-hcd") and b42e8090ba93 ("USB: UDC:
>> Implement udc_async_callbacks in net2280").
>>
> thanks, this is better, lower driver only need change several places.
>> You just need to write a corresponding patch implementing the
>> async_callbacks op for dwc3.
> yes, i will do.
>>
Alan, i want to discuss your suggestion again in b42e8090ba93 ("USB:
UDC:
Implement udc_async_callbacks in net2280")
+ if (dev->async_callbacks) { ----> if CPU1 saw
this is true
+ spin_unlock(&dev->lock); ---> CPU2 get
lock after this unlock,
it will set async_callbacks to false, then follow call also crash, right
?
+ tmp = dev->driver->setup(&dev->gadget,
&u.r);
+ spin_lock(&dev->lock);
+ }
>> Alan Stern
next prev parent reply other threads:[~2021-06-20 3:53 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-19 15:43 [PATCH v3 0/2] usb: udc: indroduce more api for lower gadget driver Linyu Yuan
2021-06-19 15:43 ` [PATCH v3 1/2] usb: udc: core: hide struct usb_gadget_driver to " Linyu Yuan
2021-06-20 2:13 ` Alan Stern
2021-06-20 3:46 ` linyyuan
2021-06-20 3:53 ` linyyuan [this message]
2021-06-20 13:47 ` Alan Stern
2021-06-21 1:37 ` linyyuan
2021-06-21 13:53 ` Alan Stern
2021-06-19 15:43 ` [PATCH v3 2/2] usb: dwc3: fix race of usb_gadget_driver operation Linyu Yuan
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