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  1. 17 Jul, 2023 2 commits
    • Marc Kleine-Budde's avatar
      can: gs_usb: fix time stamp counter initialization · 5886e4d5
      Marc Kleine-Budde authored 
      If the gs_usb device driver is unloaded (or unbound) before the
interface is shut down, the USB stack first calls the struct
usb_driver::disconnect and then the struct net_device_ops::ndo_stop
callback.

In gs_usb_disconnect() all pending bulk URBs are killed, i.e. no more
RX'ed CAN frames are send from the USB device to the host. Later in
gs_can_close() a reset control message is send to each CAN channel to
remove the controller from the CAN bus. In this race window the USB
device can still receive CAN frames from the bus and internally queue
them to be send to the host.

At least in the current version of the candlelight firmware, the queue
of received CAN frames is not emptied during the reset command. After
loading (or binding) the gs_usb driver, new URBs are submitted during
the struct net_device_ops::ndo_open callback and the candlelight
firmware starts sending its already queued CAN frames to the host.

However, this scenario was not considered when implementing the
hardware timestamp function. The cycle counter/time counter
infrastructure is set up (gs_usb_timestamp_init()) after the USBs are
submitted, resulting in a NULL pointer dereference if
timecounter_cyc2time() (via the call chain:
gs_usb_receive_bulk_callback() -> gs_usb_set_timestamp() ->
gs_usb_skb_set_timestamp()) is called too early.

Move the gs_usb_timestamp_init() function before the URBs are
submitted to fix this problem.

For a comprehensive solution, we need to consider gs_usb devices with
more than 1 channel. The cycle counter/time counter infrastructure is
setup per channel, but the RX URBs are per device. Once gs_can_open()
of _a_ channel has been called, and URBs have been submitted, the
gs_usb_receive_bulk_callback() can be called for _all_ available
channels, even for channels that are not running, yet. As cycle
counter/time counter has not set up, this will again lead to a NULL
pointer dereference.

Convert the cycle counter/time counter from a "per channel" to a "per
device" functionality. Also set it up, before submitting any URBs to
the device.

Further in gs_usb_receive_bulk_callback(), don't process any URBs for
not started CAN channels, only resubmit the URB.

Fixes: 45dfa45f ("can: gs_usb: add RX and TX hardware timestamp support")
Closes: https://github.com/candle-usb/candleLight_fw/issues/137#issuecomment-1623532076
Cc: stable@vger.kernel.org
Cc: John Whittington <git@jbrengineering.co.uk>
Link: https://lore.kernel.org/all/20230716-gs_usb-fix-time-stamp-counter-v1-2-9017cefcd9d5@pengutronix.deSigned-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
      5886e4d5
    • Marc Kleine-Budde's avatar
      can: gs_usb: gs_can_open(): improve error handling · 2603be9e
      Marc Kleine-Budde authored 
      The gs_usb driver handles USB devices with more than 1 CAN channel.
The RX path for all channels share the same bulk endpoint (the
transmitted bulk data encodes the channel number). These per-device
resources are allocated and submitted by the first opened channel.

During this allocation, the resources are either released immediately
in case of a failure or the URBs are anchored. All anchored URBs are
finally killed with gs_usb_disconnect().

Currently, gs_can_open() returns with an error if the allocation of a
URB or a buffer fails. However, if usb_submit_urb() fails, the driver
continues with the URBs submitted so far, even if no URBs were
successfully submitted.

Treat every error as fatal and free all allocated resources
immediately.

Switch to goto-style error handling, to prepare the driver for more
per-device resource allocation.

Cc: stable@vger.kernel.org
Cc: John Whittington <git@jbrengineering.co.uk>
Link: https://lore.kernel.org/all/20230716-gs_usb-fix-time-stamp-counter-v1-1-9017cefcd9d5@pengutronix.deSigned-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
      2603be9e
  3. 15 Jul, 2023 10 commits
  5. 14 Jul, 2023 9 commits
  7. 13 Jul, 2023 17 commits
  9. 12 Jul, 2023 2 commits
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