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The handling of CAN bus errors typically consist of allocating a CAN
error SKB using alloc_can_err_skb() followed by stats handling and
filling the error details in the newly allocated CAN error SKB. Even
if the allocation of the SKB fails the stats handling should not be
skipped.
The common pattern in CAN drivers is to allocate the skb and work on
the struct can_frame pointer "cf", if it has been assigned by
alloc_can_err_skb().
| skb = alloc_can_err_skb(priv->ndev, &cf);
|
| /* RX errors */
| if (bdiag1 & (MCP251XFD_REG_BDIAG1_DCRCERR |
| MCP251XFD_REG_BDIAG1_NCRCERR)) {
| netdev_dbg(priv->ndev, "CRC error\n");
|
| stats->rx_errors++;
| if (cf)
| cf->data[3] |= CAN_ERR_PROT_LOC_CRC_SEQ;
| }
In case of an OOM alloc_can_err_skb() returns NULL, but doesn't set
"cf" to NULL as well. For the above pattern to work the "cf" has to be
initialized to NULL, which is easily forgotten.
To solve this kind of problems, set "cf" to NULL if
alloc_can_err_skb() returns NULL.
Link: https://lore.kernel.org/r/20210402102245.1512583-1-mkl@pengutronix.de
Suggested-by: Vincent MAILHOL <mailhol.vincent@wanadoo.fr>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
In order to implement byte queue limits (bql) in CAN drivers, the
length of the CAN frame needs to be passed into the networking stack
even if the transmission failed for some reason.
To avoid to calculate this length twice, extend can_free_echo_skb() to
return that value. Convert all users of this function, too.
This patch is the natural extension of commit:
| 9420e1d495e2 ("can: dev: can_get_echo_skb(): extend to return can
| frame length")
Link: https://lore.kernel.org/r/20210319142700.305648-3-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
A out of bounds access to "struct can_priv::echo_skb" leads to a
kernel crash. Better print a sensible warning message instead and try
to recover.
This patch is similar to:
| e7a6994d043a ("can: dev: __can_get_echo_skb(): Don't crash the kernel
| if can_priv::echo_skb is accessed out of bounds")
Link: https://lore.kernel.org/r/20210319142700.305648-2-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
So far the creation of the TX echo skb was optional and can be
controlled by the local sender of a CAN frame.
It turns out that the TX echo CAN skb can be piggybacked to carry
information in the driver from the TX- to the TX-complete handler.
Several drivers already use the return value of
can_get_echo_skb() (which is the length of the data field in the CAN
frame) for their number of transferred bytes statistics. The
statistics are not working if CAN echo skbs are disabled.
Another use case is to calculate and set the CAN frame length on the
wire, which is needed for BQL support in both the TX and TX-completion
handler.
For now in can_put_echo_skb(), which is called from the TX handler,
the skb carrying the CAN frame is discarded if no TX echo is
requested, leading to the above illustrated problems.
This patch changes the can_put_echo_skb() function, so that the echo
skb is always generated. If the sender requests no echo, the echo skb
is consumed in __can_get_echo_skb() without being passed into the RX
handler of the networking stack, but the CAN data length and CAN frame
length information is properly returned.
Link: https://lore.kernel.org/r/20210309211904.3348700-1-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Call skb_tx_timestamp() within can_put_echo_skb() so that a software tx
timestamp gets attached to the skb.
There two main reasons to include this call in can_put_echo_skb():
* It easily allow to enable the tx timestamp on all devices with
just one small change.
* According to Documentation/networking/timestamping.rst, the tx
timestamps should be generated in the device driver as close as possible,
but always prior to passing the packet to the network interface. During the
call to can_put_echo_skb(), the skb gets cloned meaning that the driver
should not dereference the skb variable anymore after can_put_echo_skb()
returns. This makes can_put_echo_skb() the very last place we can use the
skb without having to access the echo_skb[] array.
Remark: by default, skb_tx_timestamp() does nothing. It needs to be activated
by passing the SOF_TIMESTAMPING_TX_SOFTWARE flag either through socket options
or control messages.
References:
* Support for the error queue in CAN RAW sockets (which is needed for
tx timestamps) was introduced in:
https://git.kernel.org//torvalds/c/eb88531bdbfaafb827192d1fc6c5a3fcc4fadd96
* Put the call to skb_tx_timestamp() just before adding it to the
array:
https://lore.kernel.org/r/043c3ea1-6bdd-59c0-0269-27b2b5b36cec@victronenergy.com
* About Tx hardware timestamps
https://lore.kernel.org/r/20210111171152.GB11715@hoboy.vegasvil.org
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/r/20210112095437.6488-2-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
In order to implement byte queue limits (bql) in CAN drivers, the length of the
CAN frame needs to be passed into the networking stack after queueing and after
transmission completion.
To avoid to calculate this length twice, extend can_get_echo_skb() to return
that value. Convert all users of this function, too.
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/r/20210111141930.693847-14-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Add a frame_len argument to can_put_echo_skb() which is used to save length of
the CAN frame into field frame_len of struct can_skb_priv so that it can be
later used after transmission completion. Convert all users of this function,
too.
Drivers which implement BQL call can_put_echo_skb() with the output of
can_skb_get_frame_len(skb) and drivers which do not simply pass zero as an
input (in the same way that NULL would be given to can_get_echo_skb()). This
way, we have a nice symmetry between the two echo functions.
Link: https://lore.kernel.org/r/20210111061335.39983-1-mailhol.vincent@wanadoo.fr
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/r/20210111141930.693847-13-mkl@pengutronix.de
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
In order to implement byte queue limits (bql) in CAN drivers, the length of the
CAN frame needs to be passed into the networking stack after queueing and after
transmission completion.
To avoid to calculate this length twice, extend the struct can_skb_priv to hold
the length of the CAN frame and extend __can_get_echo_skb() to return that
value.
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/r/20210111141930.693847-12-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This patch moves the skb related code of the CAN device infrastructure into a
separate file.
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/r/20210111141930.693847-6-mkl@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
