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db8686b24a
commit 634775a752a86784511018a108f3b530cc3399a7 upstream.
The role switch registration and set_role() can happen in parallel as they
are invoked independent of each other. There is a possibility that a driver
might spend significant amount of time in usb_role_switch_register() API
due to the presence of time intensive operations like component_add()
which operate under common mutex. This leads to a time window after
allocating the switch and before setting the registered flag where the set
role notifications are dropped. Below timeline summarizes this behavior
Thread1 | Thread2
usb_role_switch_register() |
| |
---> allocate switch |
| |
---> component_add() | usb_role_switch_set_role()
| | |
| | --> Drop role notifications
| | since sw->registered
| | flag is not set.
| |
--->Set registered flag.|
To avoid this, set the registered flag early on in the switch register
API.
Fixes: b787a3e78175 ("usb: roles: don't get/set_role() when usb_role_switch is unregistered")
Cc: stable <stable@kernel.org>
Signed-off-by: Elson Roy Serrao <quic_eserrao@quicinc.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20250206193950.22421-1-quic_eserrao@quicinc.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
``make pdfdocs``. The formatted documentation can also be read online at:
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.