With CONFIG_KASAN enabled and gcc-7, we get a warning about rather high
stack usage (with a private patch set I have to turn on this warning,
which I intend to get into the next kernel release):
wireless/ralink/rt2x00/rt2800lib.c: In function 'rt2800_bw_filter_calibration':
wireless/ralink/rt2x00/rt2800lib.c:7990:1: error: the frame size of 2144 bytes is larger than 1536 bytes [-Werror=frame-larger-than=]
The problem is that KASAN inserts a redzone around each local variable
that gets passed by reference, and the newly added function has a lot
of them.
This is a semi-automated conversion to change rt2800_rfcsr_read to return
the register contents instead of passing them by value, resulting in
much better object code. The majority of the patch was done using: