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Commit 4cb5e42f authored by Tilman Schmidt's avatar Tilman Schmidt Committed by David S. Miller
Browse files

isdn/gigaset: unclog bas_gigaset AT response pipe 



Recover from a lost HD_RECEIVEATDATA_ACK message by sending a
zero-length HD_READ_ATMESSAGE command when ev_layer sends "+++".

Signed-off-by: default avatarTilman Schmidt <tilman@imap.cc>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 60798c68

drivers/isdn/gigaset/bas-gigaset.c

+22 −0
Original line number Diff line number Diff line
@@ -1896,6 +1896,28 @@ static int gigaset_write_cmd(struct cardstate *cs, struct cmdbuf_t *cb) 
	 * The next command will reopen the AT channel automatically.

	 */

	if (cb->len == 3 && !memcmp(cb->buf, "+++", 3)) {

		/* If an HD_RECEIVEATDATA_ACK message remains unhandled

		 * because of an error, the base never sends another one.

		 * The response channel is thus effectively blocked.

		 * Closing and reopening the AT channel does *not* clear

		 * this condition.

		 * As a stopgap measure, submit a zero-length AT read

		 * before closing the AT channel. This has the undocumented

		 * effect of triggering a new HD_RECEIVEATDATA_ACK message

		 * from the base if necessary.

		 * The subsequent AT channel close then discards any pending

		 * messages.

		 */

		spin_lock_irqsave(&cs->lock, flags);

		if (!(cs->hw.bas->basstate & BS_ATRDPEND)) {

			kfree(cs->hw.bas->rcvbuf);

			cs->hw.bas->rcvbuf = NULL;

			cs->hw.bas->rcvbuf_size = 0;

			cs->hw.bas->retry_cmd_in = 0;

			atread_submit(cs, 0);

		}

		spin_unlock_irqrestore(&cs->lock, flags);



		rc = req_submit(cs->bcs, HD_CLOSE_ATCHANNEL, 0, BAS_TIMEOUT);

		if (cb->wake_tasklet)

			tasklet_schedule(cb->wake_tasklet);