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b1a71c9047
usb_composite_setup_continue() may be called before composite_setup()
return USB_GADGET_DELAYED_STATUS, then the controller driver will
delay status stage after composite_setup() finish, but the class driver
don't ask the controller to continue delayed status anymore, this will
cause control transfer timeout.
happens when use mass storage (also enabled other class driver):
cpu1: cpu2
handle_setup(SET_CONFIG) //gadget driver
unlock (g->lock)
gadget_driver->setup()
composite_setup()
lock(cdev->lock)
set_config()
fsg_set_alt() // maybe some times due to many class are enabled
raise FSG_STATE_CONFIG_CHANGE
return USB_GADGET_DELAYED_STATUS
handle_exception()
usb_composite_setup_continue()
unlock(cdev->lock)
lock(cdev->lock)
ep0_queue()
lock (g->lock)
//no delayed status, nothing todo
unlock (g->lock)
unlock(cdev->lock)
return USB_GADGET_DELAYED_STATUS // composite_setup
lock (g->lock)
get USB_GADGET_DELAYED_STATUS //handle_setup [1]
Try to fix the race condition as following:
After the driver gets USB_GADGET_DELAYED_STATUS at [1], if we find
there is a usb_request in ep0 request list, it means composite already
asked us to continue delayed status by usb_composite_setup_continue(),
so we skip request about delayed_status by composite_setup() and still
do status stage.
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1570611900-7112-2-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.