On 11.07.2023 17:26:47, Mike Looijmans wrote: > When there's an error attempting to store the BER counter, don't abort > but continue shutting down the chip as required. If you refer to an error by __mcp251xfd_get_berr_counter(), it's not a store error, but a failure of regmap_read(priv->map_reg, MCP251XFD_REG_TREC, &trec). By default the SPI transfers are CRC enabled and no/wrong data from the chip will be detected and return an error here (after 3 retires). In out of memory conditions or other kernel errors might be possible here, too. Have you seen a problem here? But as we shut down the chip here anyways, we can ignore the error here. > After disabling communications, also stop the TX queue with a call to > netif_stop_queue. can_bus_off() will call netif_carrier_off(), isn't this sufficient? Have you enabled automatic restart in case of bus off? I think the netdev watchdog will kick you, if the interface has a stooped queue for too long (IIRC 5 seconds). > When the interface restarts, mcp251xfd_set_mode will > call netif_wake_queue and resume. > > This fixes a hangup in either send() or poll() from userspace. To > reproduce: I ran "cansequence can0 -p" to flood the system with packets. > While running that, I shorted the CAN signals, causing a bus error. > Usually communications would resume after the CAN bus restarted, but > sometimes the system got stuck and refused to send any more packets. > The sending process would be in either poll() or send(), waiting for > the queue to resume. To "unstuck" the process from send() it was > sufficient to send any packet on the can interface from another > process. To get it out of the poll() hang, only bringing the can > interface down (and up) would work. > > After adding the netif_stop_queue call, I was unable to reproduce the > problem. The newly added netif_stop_queue() will cause the netif_wake_queue() in the mcp251xfd_set_mode() to actually wake the queue. If you observe a problem, I think it's a general problem, so all drivers would be effected. > Signed-off-by: Mike Looijmans <mike.looijmans@xxxxxxxx> Marc -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung Nürnberg | Phone: +49-5121-206917-129 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-9 |
Attachment:
signature.asc
Description: PGP signature
