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0443b3f443
Following the device's documentation guidance, reading a packet from the device or writing a packet to it must be atomic. Previously, only reading device's vacancy (before writing on it) or occupancy (before reading from it) was locked. Hence, effectively reading the packet or writing the packet wasn't locked at all. However, reading a packet (and writing one, to a lesser extent) requires to read 3 different registers in a specific order, without missing one or else we should reset the device. This patch fixes the device's locking mechanism on the FIFO character device. As the device was using copy_from_user() and copy_to_user(), we need to replace spinlocks with mutexes. Signed-off-by: Quentin Deslandes <quentin.deslandes@itdev.co.uk> Link: https://lore.kernel.org/r/20200121103958.12941-1-quentin.deslandes@itdev.co.uk 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.