netdev - Re: [PATCH v3 08/11] can: bcm: Add LIN answer offloading for responder mode

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Date: Thu, 09 May 2024 19:06:58 +0200
From: Christoph Fritz <christoph.fritz@...dev.de>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: Jiri Slaby <jirislaby@...nel.org>, Oliver Hartkopp
 <socketcan@...tkopp.net>,  Marc Kleine-Budde <mkl@...gutronix.de>, Vincent
 Mailhol <mailhol.vincent@...adoo.fr>, "David S . Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski
 <kuba@...nel.org>,  Paolo Abeni <pabeni@...hat.com>, Rob Herring
 <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,  Conor Dooley
 <conor+dt@...nel.org>, Jiri Kosina <jikos@...nel.org>, Benjamin Tissoires
 <bentiss@...nel.org>,  Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Sebastian Reichel <sre@...nel.org>, Linus Walleij
 <linus.walleij@...aro.org>, Andreas Lauser
 <andreas.lauser@...cedes-benz.com>,  Jonathan Corbet <corbet@....net>,
 Pavel Pisa <pisa@....felk.cvut.cz>, linux-can@...r.kernel.org,  Netdev
 <netdev@...r.kernel.org>, devicetree@...r.kernel.org,
 linux-input@...r.kernel.org,  linux-serial <linux-serial@...r.kernel.org>
Subject: Re: [PATCH v3 08/11] can: bcm: Add LIN answer offloading for
 responder mode

On Mon, 2024-05-06 at 20:08 +0300, Ilpo Järvinen wrote:
> On Thu, 2 May 2024, Christoph Fritz wrote:
> 
> > Enhance CAN broadcast manager with RX_LIN_SETUP and RX_LIN_DELETE
> > operations to setup automatic LIN frame responses in responder mode.
> > 
> > Additionally, the patch introduces the LIN_EVENT_FRAME flag to
> > setup event-triggered LIN frames.
> > 
> > Signed-off-by: Christoph Fritz <christoph.fritz@...dev.de>
> > ---
> >  include/uapi/linux/can/bcm.h |  5 ++-
> >  net/can/bcm.c                | 74 +++++++++++++++++++++++++++++++++++-
> >  2 files changed, 77 insertions(+), 2 deletions(-)
> > 
> > diff --git a/include/uapi/linux/can/bcm.h b/include/uapi/linux/can/bcm.h
> > index f1e45f533a72c..c46268a114078 100644
> > --- a/include/uapi/linux/can/bcm.h
> > +++ b/include/uapi/linux/can/bcm.h
> > @@ -86,7 +86,9 @@ enum {
> >  	TX_EXPIRED,	/* notification on performed transmissions (count=0) */
> >  	RX_STATUS,	/* reply to RX_READ request */
> >  	RX_TIMEOUT,	/* cyclic message is absent */
> > -	RX_CHANGED	/* updated CAN frame (detected content change) */
> > +	RX_CHANGED,	/* updated CAN frame (detected content change) */
> > +	RX_LIN_SETUP,	/* create auto-response for LIN frame */
> > +	RX_LIN_DELETE,  /* remove auto-response for LIN frame */
> >  };
> >  
> >  #define SETTIMER            0x0001
> > @@ -101,5 +103,6 @@ enum {
> >  #define TX_RESET_MULTI_IDX  0x0200
> >  #define RX_RTR_FRAME        0x0400
> >  #define CAN_FD_FRAME        0x0800
> > +#define LIN_EVENT_FRAME     0x1000
> >  
> >  #endif /* !_UAPI_CAN_BCM_H */
> > diff --git a/net/can/bcm.c b/net/can/bcm.c
> > index 27d5fcf0eac9d..a717e594234d1 100644
> > --- a/net/can/bcm.c
> > +++ b/net/can/bcm.c
> > @@ -59,6 +59,7 @@
> >  #include <linux/can/bcm.h>
> >  #include <linux/slab.h>
> >  #include <net/sock.h>
> > +#include <net/lin.h>
> >  #include <net/net_namespace.h>
> >  
> >  /*
> > @@ -1330,6 +1331,59 @@ static int bcm_tx_send(struct msghdr *msg, int ifindex, struct sock *sk,
> >  	return cfsiz + MHSIZ;
> >  }
> >  
> > +static int bcm_lin_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
> > +			 int ifindex, struct sock *sk, int cfsiz, int is_active)
> > +{
> > +	struct lin_responder_answer answ;
> > +	struct net_device *dev;
> > +	struct sk_buff *skb;
> > +	struct canfd_frame cf;
> > +	netdevice_tracker tracker;
> > +	size_t sz;
> > +	int ret;
> > +
> > +	if (msg_head->nframes > 1)
> > +		return -EINVAL;
> > +
> > +	if (!(msg_head->flags & CAN_FD_FRAME))
> > +		return -EINVAL;
> > +
> > +	ret = memcpy_from_msg(&cf, msg, cfsiz);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	answ.lf.lin_id = cf.can_id & LIN_ID_MASK;
> > +	answ.is_active = is_active;
> > +	answ.is_event_frame = !!(msg_head->flags & LIN_EVENT_FRAME);
> > +	answ.event_associated_id = msg_head->can_id;
> > +	answ.lf.len = min(cf.len, LIN_MAX_DLEN);
> > +	memcpy(answ.lf.data, cf.data, answ.lf.len);
> > +	sz = min(sizeof(struct lin_responder_answer), sizeof(cf.data));
> > +	cf.can_id |= LIN_RXOFFLOAD_DATA_FLAG;
> > +	memcpy(cf.data, &answ, sz);
> > +
> > +	dev = netdev_get_by_index(sock_net(sk), ifindex, &tracker, GFP_KERNEL);
> > +	if (!dev)
> > +		return -ENODEV;
> > +
> > +	skb = alloc_skb(cfsiz + sizeof(struct can_skb_priv), gfp_any());
> 
> You just called the other function with GFP_KERNEL and you now need 
> gfp_any(). Which is correct??

I guess GFP_KERNEL but I'm not sure so I'll let gfp_any() decide for
netdev_get_by_index() too.

> 
> > +	if (!skb)
> > +		goto lin_out;
> > +
> > +	can_skb_reserve(skb);
> > +	can_skb_prv(skb)->ifindex = dev->ifindex;
> > +	can_skb_prv(skb)->skbcnt = 0;
> > +	skb_put_data(skb, &cf, cfsiz);
> > +
> > +	skb->dev = dev;
> > +	can_skb_set_owner(skb, sk);
> > +	ret = can_send(skb, 1); /* send with loopback */
> > +
> > +lin_out:
> > +	netdev_put(dev, &tracker);
> > +	return ret;
> > +}
> > +
> >  /*
> >   * bcm_sendmsg - process BCM commands (opcodes) from the userspace
> >   */
> > @@ -1429,12 +1483,30 @@ static int bcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
> >  
> >  	case TX_SEND:
> >  		/* we need exactly one CAN frame behind the msg head */
> > -		if ((msg_head.nframes != 1) || (size != cfsiz + MHSIZ))
> > +		if (msg_head.nframes != 1 || size != cfsiz + MHSIZ)
> 
> Unrelated style fix, doesn't belong to this patch.

OK

...

thanks
  -- Christoph