dev_queue_xmit(9) [centos man page]

DEV_QUEUE_XMIT(9)					      Network device support						 DEV_QUEUE_XMIT(9)

NAME

       dev_queue_xmit - transmit a buffer

SYNOPSIS

       int dev_queue_xmit(struct sk_buff * skb);

ARGUMENTS

       skb
	   buffer to transmit

DESCRIPTION

       Queue a buffer for transmission to a network device. The caller must have set the device and priority and built the buffer before calling
       this function. The function can be called from an interrupt.

       A negative errno code is returned on a failure. A success does not guarantee the frame will be transmitted as it may be dropped due to
       congestion or traffic shaping.

       ----------------------------------------------------------------------------------- I notice this method can also return errors from the
       queue disciplines, including NET_XMIT_DROP, which is a positive value. So, errors can also be positive.

       Regardless of the return value, the skb is consumed, so it is currently difficult to retry a send to this method. (You can bump the ref
       count before sending to hold a reference for retry if you are careful.)

       When calling this method, interrupts MUST be enabled. This is because the BH enable code must have IRQs enabled so that it will not
       deadlock. --BLG

COPYRIGHT

Kernel Hackers Manual 3.10					     June 2014							 DEV_QUEUE_XMIT(9)

WIMAX_MSG_ALLOC(9)						 Linux Networking						WIMAX_MSG_ALLOC(9)

NAME

       wimax_msg_alloc - Create a new skb for sending a message to userspace

SYNOPSIS

       struct sk_buff * wimax_msg_alloc(struct wimax_dev * wimax_dev, const char * pipe_name, const void * msg, size_t size, gfp_t gfp_flags);

ARGUMENTS

       wimax_dev
	   WiMAX device descriptor

       pipe_name
	   "named pipe" the message will be sent to

       msg
	   pointer to the message data to send

       size
	   size of the message to send (in bytes), including the header.

       gfp_flags
	   flags for memory allocation.

RETURNS

       0 if ok, negative errno code on error

DESCRIPTION

       Allocates an skb that will contain the message to send to user space over the messaging pipe and initializes it, copying the payload.

       Once this call is done, you can deliver it with wimax_msg_send.

IMPORTANT

       Don't use skb_push/skb_pull/skb_reserve on the skb, as wimax_msg_send depends on skb->data being placed at the beginning of the user
       message.

       Unlike other WiMAX stack calls, this call can be used way early, even before wimax_dev_add is called, as long as the wimax_dev->net_dev
       pointer is set to point to a proper net_dev. This is so that drivers can use it early in case they need to send stuff around or communicate
       with user space.

COPYRIGHT

Kernel Hackers Manual 3.10					     June 2014							WIMAX_MSG_ALLOC(9)