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/openbmc/linux/drivers/net/can/usb/
H A Dgs_usb.cdiff 29a8c9ec9090b335ece3bd58d779af7f569b5a65 Mon Sep 19 02:53:45 CDT 2022 Marc Kleine-Budde <mkl@pengutronix.de> can: gs_usb: add missing lock to protect struct timecounter::cycle_last

The struct timecounter::cycle_last is a 64 bit variable, read by
timecounter_cyc2time(), and written by timecounter_read(). On 32 bit
architectures this is not atomic.

Add a spinlock to protect access to struct timecounter::cycle_last. In
the gs_usb_timestamp_read() callback the lock is dropped to execute a
sleeping synchronous USB transfer. This is safe, as the variable we
want to protect is accessed during this call.

Fixes: 45dfa45f52e6 ("can: gs_usb: add RX and TX hardware timestamp support")
Link: https://lore.kernel.org/all/20220920100416.959226-3-mkl@pengutronix.de
Cc: John Whittington <git@jbrengineering.co.uk>
Tested-by: John Whittington <git@jbrengineering.co.uk>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>