A dead lock may happen before this patch:
rptun thread (usrsock_rpmsg_recvfrom_handler):
Gets all tx payload but waiting net_lock in psock_recvfrom
net driver thread (higher priority):
Receives a packet, holding net_lock, calling usrsock_rpmsg_send_event
But no tx buffer left, so rpmsg_send blocks, and won't release net_lock
In short:
Rptun: Hold all `tx_payload_buffer` -> want `net_lock`
Driver: Hold `net_lock` -> want `tx_payload_buffer`
This patch use net_lock to combine get_tx_payload and recvfrom together,
then:
- If it's waiting net_lock, tx payload will not be held, other threads
may get tx buffer and do their work.
- If net_lock is got, it won't be disturbed before finish receiving,
then tx payload won't have chance to be blocked before releasing.
Signed-off-by: Zhe Weng <wengzhe@xiaomi.com>
e4721cef5c