From: Daniel Starke daniel.starke@siemens.com
[ Upstream commit 59ff0680ecbfec742b1e0381e7cc46b41eb06647 ]
The current implementation constipates all transmission paths during flow control except for flow control frames. However, these may not be located at the beginning of the transmission queue of the control channel. Ensure that flow control frames in the transmission queue for the control channel are always handled even if constipated by skipping through other messages.
Fixes: 0af021678d5d ("tty: n_gsm: fix deadlock and link starvation in outgoing data path") Signed-off-by: Daniel Starke daniel.starke@siemens.com Link: https://lore.kernel.org/r/20220707113223.3685-3-daniel.starke@siemens.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/tty/n_gsm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c index 8b8c7312935f..7749de4f269a 100644 --- a/drivers/tty/n_gsm.c +++ b/drivers/tty/n_gsm.c @@ -891,7 +891,7 @@ static int gsm_data_kick(struct gsm_mux *gsm) /* Serialize control messages and control channel messages first */ list_for_each_entry_safe(msg, nmsg, &gsm->tx_ctrl_list, list) { if (gsm->constipated && !gsm_is_flow_ctrl_msg(msg)) - return -EAGAIN; + continue; ret = gsm_send_packet(gsm, msg); switch (ret) { case -ENOSPC: