net: qrtr: Send HELLO message on endpoint register

HELLO is currently handled entirely by the name server (NS): it is
sent once as a broadcast when the NS initializes, and again as a
reply whenever the NS receives an inbound HELLO from a remote.

Some remote QRTR endpoints (e.g. an external WLAN chipset attached
over MHI) operate in a slave role: they only ever send a HELLO in
response to one they receive, and never initiate. Since the host cannot
tell in advance which remotes behave this way, if the host also only
replies, both sides wait on the other to speak first and no HELLO is
ever exchanged, stalling further communication.

To fix this:
- Transfer HELLO handshake ownership to the core layer. A HELLO is
  now sent once, per endpoint, at registration time.
- Schedule a delayed work item on endpoint registration to send a
  HELLO once the name server is bound. The work reschedules itself
  with a 100ms backoff if the name server socket is not yet bound or
  if allocating the control packet fails, so a transient startup
  condition does not abandon the handshake permanently.
- Enforce HELLO-first ordering by dropping non-HELLO packets and
  returning -EAGAIN until the HELLO is confirmed sent, using bool
  hello_sent guarded by ep_lock to make the gate check atomic with
  xmit().
- Skip nodes with nid == QRTR_EP_NID_AUTO in bcast_enqueue(), to avoid
  broadcasting control packets with QRTR_EP_NID_AUTO as the destination
  node ID.
- Remove say_hello() from the name server's ctrl_cmd_hello() handler
  and from qrtr_ns_init(); the core layer is now the sole sender of
  the outbound HELLO. This removes the NS's reply-on-receive
  behaviour without a replacement.

Signed-off-by: Chris Lew <christopher.lew@oss.qualcomm.com>
Co-developed-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
Signed-off-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
Co-developed-by: Pranav Mahesh Phansalkar <pranav.phansalkar@oss.qualcomm.com>
Signed-off-by: Pranav Mahesh Phansalkar <pranav.phansalkar@oss.qualcomm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

0 files changed, 0 insertions, 0 deletions