n_gsm: uplink SKBs accumulate on list

commit 192b6041e75bb4a2aae73834037038cea139a92d upstream.

gsm_dlci_data_kick will not call any output function if tx_bytes > THRESH_LO
furthermore it will call the output function only once if tx_bytes == 0
If the size of the IP writes are on the order of THRESH_LO
we can get into a situation where skbs accumulate on the outbound list
being starved for events to call the output function.

gsm_dlci_data_kick now calls the sweep function when tx_bytes==0

Signed-off-by: Russ Gorby <russ.gorby@intel.com>
Tested-by: Kappel, LaurentX <laurentx.kappel@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index cb3e4aa..3391fdc 100644 (file)
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -971,16 +971,19 @@ static void gsm_dlci_data_sweep(struct gsm_mux *gsm)
 static void gsm_dlci_data_kick(struct gsm_dlci *dlci)
 {
        unsigned long flags;
+       int sweep;
 
        spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
        /* If we have nothing running then we need to fire up */
+       sweep = (dlci->gsm->tx_bytes < TX_THRESH_LO);
        if (dlci->gsm->tx_bytes == 0) {
                if (dlci->net)
                        gsm_dlci_data_output_framed(dlci->gsm, dlci);
                else
                        gsm_dlci_data_output(dlci->gsm, dlci);
-       } else if (dlci->gsm->tx_bytes < TX_THRESH_LO)
-               gsm_dlci_data_sweep(dlci->gsm);
+       }
+       if (sweep)
+               gsm_dlci_data_sweep(dlci->gsm);
        spin_unlock_irqrestore(&dlci->gsm->tx_lock, flags);
 }