On 28.06.2022 11:48:48, Dario Binacchi wrote: > Hi Marc, > > On Tue, Jun 28, 2022 at 11:28 AM Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> wrote: > > > > On 14.06.2022 14:28:14, Dario Binacchi wrote: > > > As suggested by commit [1], now the driver uses the functions and the > > > data structures provided by the CAN network device driver interface. > > > > > > Currently the driver doesn't implement a way to set bitrate for SLCAN > > > based devices via ip tool, so you'll have to do this by slcand or > > > slcan_attach invocation through the -sX parameter: > > > > > > - slcan_attach -f -s6 -o /dev/ttyACM0 > > > - slcand -f -s8 -o /dev/ttyUSB0 > > > > > > where -s6 in will set adapter's bitrate to 500 Kbit/s and -s8 to > > > 1Mbit/s. > > > See the table below for further CAN bitrates: > > > - s0 -> 10 Kbit/s > > > - s1 -> 20 Kbit/s > > > - s2 -> 50 Kbit/s > > > - s3 -> 100 Kbit/s > > > - s4 -> 125 Kbit/s > > > - s5 -> 250 Kbit/s > > > - s6 -> 500 Kbit/s > > > - s7 -> 800 Kbit/s > > > - s8 -> 1000 Kbit/s > > > > > > In doing so, the struct can_priv::bittiming.bitrate of the driver is not > > > set and since the open_candev() checks that the bitrate has been set, it > > > must be a non-zero value, the bitrate is set to a fake value (-1U) > > > before it is called. > > > > > > The patch also changes the slcan_devs locking from rtnl to spin_lock. The > > > change was tested with a kernel with the CONFIG_PROVE_LOCKING option > > > enabled that did not show any errors. > > > > You're not allowed to call alloc_candev() with a spin_lock held. See > > today's kernel test robot mail: > > > > | https://lore.kernel.org/all/YrpqO5jepAvv4zkf@xsang-OptiPlex-9020 > > > > I think it's best to keep the rtnl for now. > > The rtnl_lock() uses a mutex while I used a spin_lock. > > static DEFINE_MUTEX(rtnl_mutex); > > void rtnl_lock(void) > { > mutex_lock(&rtnl_mutex); > } > EXPORT_SYMBOL(rtnl_lock); > > So might it be worth trying with a mutex instead of rtnl_lock(), or do > you think it is > safer to return to rtn_lock () anyway? As Max pointed out the whole static dev array is not needed at all. Just keep the rtnl, until removing the array altogether. regards, Marc -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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