@@ -5,6 +5,14 @@
*
* * THIS IS A DEVELOPMENT SNAPSHOT IT IS NOT A FINAL RELEASE *
*
+ * Outgoing path:
+ * tty -> DLCI fifo -> scheduler -> GSM MUX data queue ---o-> ldisc
+ * control message -> GSM MUX control queue --ยด
+ *
+ * Incoming path:
+ * ldisc -> gsm_queue() -o--> tty
+ * `-> gsm_control_response()
+ *
* TO DO:
* Mostly done: ioctls for setting modes/timing
* Partly done: hooks so you can pull off frames to non tty devs
@@ -210,6 +218,9 @@ struct gsm_mux {
/* Events on the GSM channel */
wait_queue_head_t event;
+ /* ldisc send work */
+ struct work_struct tx_work;
+
/* Bits for GSM mode decoding */
/* Framing Layer */
@@ -241,7 +252,8 @@ struct gsm_mux {
unsigned int tx_bytes; /* TX data outstanding */
#define TX_THRESH_HI 8192
#define TX_THRESH_LO 2048
- struct list_head tx_list; /* Pending data packets */
+ struct list_head tx_ctrl_list; /* Pending control packets */
+ struct list_head tx_data_list; /* Pending data packets */
/* Control messages */
struct timer_list kick_timer; /* Kick TX queuing on timeout */
@@ -371,6 +383,11 @@ static const u8 gsm_fcs8[256] = {
static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len);
static int gsm_modem_update(struct gsm_dlci *dlci, u8 brk);
+static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
+ u8 ctrl);
+static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg);
+static void gsmld_write_trigger(struct gsm_mux *gsm);
+static void gsmld_write_task(struct work_struct *work);
/**
* gsm_fcs_add - update FCS
@@ -655,57 +672,73 @@ static int gsm_stuff_frame(const u8 *input, u8 *output, int len)
* @cr: command/response bit seen as initiator
* @control: control byte including PF bit
*
- * Format up and transmit a control frame. These do not go via the
- * queueing logic as they should be transmitted ahead of data when
- * they are needed.
- *
- * FIXME: Lock versus data TX path
+ * Format up and transmit a control frame. These should be transmitted
+ * ahead of data when they are needed.
*/
-
-static void gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
+static int gsm_send(struct gsm_mux *gsm, int addr, int cr, int control)
{
- int len;
- u8 cbuf[10];
- u8 ibuf[3];
+ struct gsm_msg *msg;
+ u8 *dp;
int ocr;
+ unsigned long flags;
+
+ msg = gsm_data_alloc(gsm, addr, 0, control);
+ if (!msg)
+ return -ENOMEM;
/* toggle C/R coding if not initiator */
ocr = cr ^ (gsm->initiator ? 0 : 1);
- switch (gsm->encoding) {
- case 0:
- cbuf[0] = GSM0_SOF;
- cbuf[1] = (addr << 2) | (ocr << 1) | EA;
- cbuf[2] = control;
- cbuf[3] = EA; /* Length of data = 0 */
- cbuf[4] = 0xFF - gsm_fcs_add_block(INIT_FCS, cbuf + 1, 3);
- cbuf[5] = GSM0_SOF;
- len = 6;
- break;
- case 1:
- case 2:
- /* Control frame + packing (but not frame stuffing) in mode 1 */
- ibuf[0] = (addr << 2) | (ocr << 1) | EA;
- ibuf[1] = control;
- ibuf[2] = 0xFF - gsm_fcs_add_block(INIT_FCS, ibuf, 2);
- /* Stuffing may double the size worst case */
- len = gsm_stuff_frame(ibuf, cbuf + 1, 3);
- /* Now add the SOF markers */
- cbuf[0] = GSM1_SOF;
- cbuf[len + 1] = GSM1_SOF;
- /* FIXME: we can omit the lead one in many cases */
- len += 2;
- break;
- default:
- WARN_ON(1);
- return;
- }
- gsmld_output(gsm, cbuf, len);
- if (!gsm->initiator) {
- cr = cr & gsm->initiator;
- control = control & ~PF;
+ msg->data -= 3;
+ dp = msg->data;
+ *dp++ = (addr << 2) | (ocr << 1) | EA;
+ *dp++ = control;
+
+ if (gsm->encoding == 0)
+ *dp++ = EA; /* Length of data = 0 */
+
+ *dp = 0xFF - gsm_fcs_add_block(INIT_FCS, msg->data, dp - msg->data);
+ msg->len = (dp - msg->data) + 1;
+
+ gsm_print_packet("Q->", addr, cr, control, NULL, 0);
+
+ spin_lock_irqsave(&gsm->tx_lock, flags);
+ list_add_tail(&msg->list, &gsm->tx_ctrl_list);
+ gsm->tx_bytes += msg->len;
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
+ gsmld_write_trigger(gsm);
+
+ return 0;
+}
+
+/**
+ * gsm_dlci_clear_queues - remove outstanding data for a DLCI
+ * @gsm: mux
+ * @dlci: clear for this DLCI
+ *
+ * Clears the data queues for a given DLCI.
+ */
+static void gsm_dlci_clear_queues(struct gsm_mux *gsm, struct gsm_dlci *dlci)
+{
+ struct gsm_msg *msg, *nmsg;
+ int addr = dlci->addr;
+ unsigned long flags;
+
+ /* Clear DLCI write fifo first */
+ spin_lock_irqsave(&dlci->lock, flags);
+ kfifo_reset(&dlci->fifo);
+ spin_unlock_irqrestore(&dlci->lock, flags);
+
+ /* Clear data packets in MUX write queue */
+ spin_lock_irqsave(&gsm->tx_lock, flags);
+ list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) {
+ if (msg->addr != addr)
+ continue;
+ gsm->tx_bytes -= msg->len;
+ list_del(&msg->list);
+ kfree(msg);
}
- gsm_print_packet("-->", addr, cr, control, NULL, 0);
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
}
/**
@@ -767,6 +800,45 @@ static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
return m;
}
+/**
+ * gsm_send_packet - sends a single packet
+ * @gsm: GSM Mux
+ * @msg: packet to send
+ *
+ * The given packet is encoded and sent out. No memory is freed.
+ * The caller must hold the gsm tx lock.
+ */
+static int gsm_send_packet(struct gsm_mux *gsm, struct gsm_msg *msg)
+{
+ int len, ret;
+
+
+ if (gsm->encoding == 0) {
+ gsm->txframe[0] = GSM0_SOF;
+ memcpy(gsm->txframe + 1, msg->data, msg->len);
+ gsm->txframe[msg->len + 1] = GSM0_SOF;
+ len = msg->len + 2;
+ } else {
+ gsm->txframe[0] = GSM1_SOF;
+ len = gsm_stuff_frame(msg->data, gsm->txframe + 1, msg->len);
+ gsm->txframe[len + 1] = GSM1_SOF;
+ len += 2;
+ }
+
+ if (debug & 4)
+ gsm_hex_dump_bytes(__func__, gsm->txframe, len);
+ gsm_print_packet("-->", msg->addr, gsm->initiator, msg->ctrl, msg->data,
+ msg->len);
+
+ ret = gsmld_output(gsm, gsm->txframe, len);
+ if (ret <= 0)
+ return ret;
+ /* FIXME: Can eliminate one SOF in many more cases */
+ gsm->tx_bytes -= msg->len;
+
+ return 0;
+}
+
/**
* gsm_is_flow_ctrl_msg - checks if flow control message
* @msg: message to check
@@ -799,59 +871,81 @@ static bool gsm_is_flow_ctrl_msg(struct gsm_msg *msg)
}
/**
- * gsm_data_kick - poke the queue
+ * gsm_data_kick - poke the queue
* @gsm: GSM Mux
- * @dlci: DLCI sending the data
*
* The tty device has called us to indicate that room has appeared in
- * the transmit queue. Ram more data into the pipe if we have any
+ * the transmit queue. Ram more data into the pipe if we have any.
* If we have been flow-stopped by a CMD_FCOFF, then we can only
- * send messages on DLCI0 until CMD_FCON
- *
- * FIXME: lock against link layer control transmissions
+ * send messages on DLCI0 until CMD_FCON. The caller must hold
+ * the gsm tx lock.
*/
-
-static void gsm_data_kick(struct gsm_mux *gsm, struct gsm_dlci *dlci)
+static int gsm_data_kick(struct gsm_mux *gsm)
{
struct gsm_msg *msg, *nmsg;
- int len;
+ struct gsm_dlci *dlci;
+ int ret;
- list_for_each_entry_safe(msg, nmsg, &gsm->tx_list, list) {
+ clear_bit(TTY_DO_WRITE_WAKEUP, &gsm->tty->flags);
+
+ /* 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;
+ ret = gsm_send_packet(gsm, msg);
+ switch (ret) {
+ case -ENOSPC:
+ return -ENOSPC;
+ case -ENODEV:
+ /* ldisc not open */
+ gsm->tx_bytes -= msg->len;
+ list_del(&msg->list);
+ kfree(msg);
continue;
- if (gsm->encoding != 0) {
- gsm->txframe[0] = GSM1_SOF;
- len = gsm_stuff_frame(msg->data,
- gsm->txframe + 1, msg->len);
- gsm->txframe[len + 1] = GSM1_SOF;
- len += 2;
- } else {
- gsm->txframe[0] = GSM0_SOF;
- memcpy(gsm->txframe + 1 , msg->data, msg->len);
- gsm->txframe[msg->len + 1] = GSM0_SOF;
- len = msg->len + 2;
- }
-
- if (debug & 4)
- gsm_hex_dump_bytes(__func__, gsm->txframe, len);
- if (gsmld_output(gsm, gsm->txframe, len) <= 0)
+ default:
+ if (ret >= 0) {
+ list_del(&msg->list);
+ kfree(msg);
+ }
break;
- /* FIXME: Can eliminate one SOF in many more cases */
- gsm->tx_bytes -= msg->len;
-
- list_del(&msg->list);
- kfree(msg);
+ }
+ }
- if (dlci) {
- tty_port_tty_wakeup(&dlci->port);
- } else {
- int i = 0;
+ if (gsm->constipated)
+ return -EAGAIN;
- for (i = 0; i < NUM_DLCI; i++)
- if (gsm->dlci[i])
- tty_port_tty_wakeup(&gsm->dlci[i]->port);
+ /* Serialize other channels */
+ if (list_empty(&gsm->tx_data_list))
+ return 0;
+ list_for_each_entry_safe(msg, nmsg, &gsm->tx_data_list, list) {
+ dlci = gsm->dlci[msg->addr];
+ /* Send only messages for DLCIs with valid state */
+ if (dlci->state != DLCI_OPEN) {
+ gsm->tx_bytes -= msg->len;
+ list_del(&msg->list);
+ kfree(msg);
+ continue;
+ }
+ ret = gsm_send_packet(gsm, msg);
+ switch (ret) {
+ case -ENOSPC:
+ return -ENOSPC;
+ case -ENODEV:
+ /* ldisc not open */
+ gsm->tx_bytes -= msg->len;
+ list_del(&msg->list);
+ kfree(msg);
+ continue;
+ default:
+ if (ret >= 0) {
+ list_del(&msg->list);
+ kfree(msg);
+ }
+ break;
}
}
+
+ return 1;
}
/**
@@ -900,9 +994,21 @@ static void __gsm_data_queue(struct gsm_dlci *dlci, struct gsm_msg *msg)
msg->data = dp;
/* Add to the actual output queue */
- list_add_tail(&msg->list, &gsm->tx_list);
+ switch (msg->ctrl & ~PF) {
+ case UI:
+ case UIH:
+ if (msg->addr > 0) {
+ list_add_tail(&msg->list, &gsm->tx_data_list);
+ break;
+ }
+ fallthrough;
+ default:
+ list_add_tail(&msg->list, &gsm->tx_ctrl_list);
+ break;
+ }
gsm->tx_bytes += msg->len;
- gsm_data_kick(gsm, dlci);
+
+ gsmld_write_trigger(gsm);
mod_timer(&gsm->kick_timer, jiffies + 10 * gsm->t1 * HZ / 100);
}
@@ -1129,32 +1235,39 @@ static int gsm_dlci_modem_output(struct gsm_mux *gsm, struct gsm_dlci *dlci,
static int gsm_dlci_data_sweep(struct gsm_mux *gsm)
{
- int len, ret = 0;
/* Priority ordering: We should do priority with RR of the groups */
- int i = 1;
-
- while (i < NUM_DLCI) {
- struct gsm_dlci *dlci;
+ int i, len, ret = 0;
+ bool sent;
+ struct gsm_dlci *dlci;
- if (gsm->tx_bytes > TX_THRESH_HI)
- break;
- dlci = gsm->dlci[i];
- if (dlci == NULL || dlci->constipated) {
- i++;
- continue;
+ while (gsm->tx_bytes < TX_THRESH_HI) {
+ for (sent = false, i = 1; i < NUM_DLCI; i++) {
+ dlci = gsm->dlci[i];
+ /* skip unused or blocked channel */
+ if (!dlci || dlci->constipated)
+ continue;
+ /* skip channels with invalid state */
+ if (dlci->state != DLCI_OPEN)
+ continue;
+ /* count the sent data per adaption */
+ if (dlci->adaption < 3 && !dlci->net)
+ len = gsm_dlci_data_output(gsm, dlci);
+ else
+ len = gsm_dlci_data_output_framed(gsm, dlci);
+ /* on error exit */
+ if (len < 0)
+ return ret;
+ if (len > 0) {
+ ret++;
+ sent = true;
+ /* The lower DLCs can starve the higher DLCs! */
+ break;
+ }
+ /* try next */
}
- if (dlci->adaption < 3 && !dlci->net)
- len = gsm_dlci_data_output(gsm, dlci);
- else
- len = gsm_dlci_data_output_framed(gsm, dlci);
- if (len < 0)
+ if (!sent)
break;
- /* DLCI empty - try the next */
- if (len == 0)
- i++;
- else
- ret++;
- }
+ };
return ret;
}
@@ -1402,7 +1515,6 @@ static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
const u8 *data, int clen)
{
u8 buf[1];
- unsigned long flags;
switch (command) {
case CMD_CLD: {
@@ -1424,9 +1536,7 @@ static void gsm_control_message(struct gsm_mux *gsm, unsigned int command,
gsm->constipated = false;
gsm_control_reply(gsm, CMD_FCON, NULL, 0);
/* Kick the link in case it is idling */
- spin_lock_irqsave(&gsm->tx_lock, flags);
- gsm_data_kick(gsm, NULL);
- spin_unlock_irqrestore(&gsm->tx_lock, flags);
+ gsmld_write_trigger(gsm);
break;
case CMD_FCOFF:
/* Modem wants us to STFU */
@@ -1629,8 +1739,6 @@ static int gsm_control_wait(struct gsm_mux *gsm, struct gsm_control *control)
static void gsm_dlci_close(struct gsm_dlci *dlci)
{
- unsigned long flags;
-
del_timer(&dlci->t1);
if (debug & 8)
pr_debug("DLCI %d goes closed.\n", dlci->addr);
@@ -1639,17 +1747,16 @@ static void gsm_dlci_close(struct gsm_dlci *dlci)
dlci->constipated = true;
if (dlci->addr != 0) {
tty_port_tty_hangup(&dlci->port, false);
- spin_lock_irqsave(&dlci->lock, flags);
- kfifo_reset(&dlci->fifo);
- spin_unlock_irqrestore(&dlci->lock, flags);
+ gsm_dlci_clear_queues(dlci->gsm, dlci);
/* Ensure that gsmtty_open() can return. */
tty_port_set_initialized(&dlci->port, 0);
wake_up_interruptible(&dlci->port.open_wait);
} else
dlci->gsm->dead = true;
- wake_up(&dlci->gsm->event);
/* A DLCI 0 close is a MUX termination so we need to kick that
back to userspace somehow */
+ gsm_dlci_data_kick(dlci);
+ wake_up(&dlci->gsm->event);
}
/**
@@ -1672,6 +1779,7 @@ static void gsm_dlci_open(struct gsm_dlci *dlci)
/* Send current modem state */
if (dlci->addr)
gsm_modem_update(dlci, 0);
+ gsm_dlci_data_kick(dlci);
wake_up(&dlci->gsm->event);
}
@@ -2222,7 +2330,7 @@ static void gsm1_receive(struct gsm_mux *gsm, unsigned char c)
} else if ((c & ISO_IEC_646_MASK) == XOFF) {
gsm->constipated = false;
/* Kick the link in case it is idling */
- gsm_data_kick(gsm, NULL);
+ gsmld_write_trigger(gsm);
return;
}
if (c == GSM1_SOF) {
@@ -2353,6 +2461,9 @@ static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc)
del_timer_sync(&gsm->kick_timer);
del_timer_sync(&gsm->t2_timer);
+ /* Finish writing to ldisc */
+ flush_work(&gsm->tx_work);
+
/* Free up any link layer users and finally the control channel */
if (gsm->has_devices) {
gsm_unregister_devices(gsm_tty_driver, gsm->num);
@@ -2364,9 +2475,12 @@ static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc)
mutex_unlock(&gsm->mutex);
/* Now wipe the queues */
tty_ldisc_flush(gsm->tty);
- list_for_each_entry_safe(txq, ntxq, &gsm->tx_list, list)
+ list_for_each_entry_safe(txq, ntxq, &gsm->tx_ctrl_list, list)
+ kfree(txq);
+ INIT_LIST_HEAD(&gsm->tx_ctrl_list);
+ list_for_each_entry_safe(txq, ntxq, &gsm->tx_data_list, list)
kfree(txq);
- INIT_LIST_HEAD(&gsm->tx_list);
+ INIT_LIST_HEAD(&gsm->tx_data_list);
}
/**
@@ -2385,6 +2499,7 @@ static int gsm_activate_mux(struct gsm_mux *gsm)
timer_setup(&gsm->kick_timer, gsm_kick_timer, 0);
timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
+ INIT_WORK(&gsm->tx_work, gsmld_write_task);
init_waitqueue_head(&gsm->event);
spin_lock_init(&gsm->control_lock);
spin_lock_init(&gsm->tx_lock);
@@ -2494,7 +2609,8 @@ static struct gsm_mux *gsm_alloc_mux(void)
spin_lock_init(&gsm->lock);
mutex_init(&gsm->mutex);
kref_init(&gsm->ref);
- INIT_LIST_HEAD(&gsm->tx_list);
+ INIT_LIST_HEAD(&gsm->tx_ctrl_list);
+ INIT_LIST_HEAD(&gsm->tx_data_list);
gsm->t1 = T1;
gsm->t2 = T2;
@@ -2651,6 +2767,47 @@ static int gsmld_output(struct gsm_mux *gsm, u8 *data, int len)
return gsm->tty->ops->write(gsm->tty, data, len);
}
+
+/**
+ * gsmld_write_trigger - schedule ldisc write task
+ * @gsm: our mux
+ */
+static void gsmld_write_trigger(struct gsm_mux *gsm)
+{
+ if (!gsm || !gsm->dlci[0] || gsm->dlci[0]->dead)
+ return;
+ schedule_work(&gsm->tx_work);
+}
+
+
+/**
+ * gsmld_write_task - ldisc write task
+ * @work: our tx write work
+ *
+ * Writes out data to the ldisc if possible. We are doing this here to
+ * avoid dead-locking. This returns if no space or data is left for output.
+ */
+static void gsmld_write_task(struct work_struct *work)
+{
+ struct gsm_mux *gsm = container_of(work, struct gsm_mux, tx_work);
+ unsigned long flags;
+ int i, ret;
+
+ /* All outstanding control channel and control messages and one data
+ * frame is sent.
+ */
+ ret = -ENODEV;
+ spin_lock_irqsave(&gsm->tx_lock, flags);
+ if (gsm->tty)
+ ret = gsm_data_kick(gsm);
+ spin_unlock_irqrestore(&gsm->tx_lock, flags);
+
+ if (ret >= 0)
+ for (i = 0; i < NUM_DLCI; i++)
+ if (gsm->dlci[i])
+ tty_port_tty_wakeup(&gsm->dlci[i]->port);
+}
+
/**
* gsmld_attach_gsm - mode set up
* @tty: our tty structure
@@ -2790,6 +2947,7 @@ static int gsmld_open(struct tty_struct *tty)
timer_setup(&gsm->kick_timer, gsm_kick_timer, 0);
timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
+ INIT_WORK(&gsm->tx_work, gsmld_write_task);
return 0;
}
@@ -2806,16 +2964,9 @@ static int gsmld_open(struct tty_struct *tty)
static void gsmld_write_wakeup(struct tty_struct *tty)
{
struct gsm_mux *gsm = tty->disc_data;
- unsigned long flags;
/* Queue poll */
- clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
- spin_lock_irqsave(&gsm->tx_lock, flags);
- gsm_data_kick(gsm, NULL);
- if (gsm->tx_bytes < TX_THRESH_LO) {
- gsm_dlci_data_sweep(gsm);
- }
- spin_unlock_irqrestore(&gsm->tx_lock, flags);
+ gsmld_write_trigger(gsm);
}
/**