linux-kernel - [PATCH 3.4 135/214] char: n_gsm: remove message filtering for contipated DLCI

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Message-Id: <20140605041657.862129320@linuxfoundation.org>
Date:	Wed,  4 Jun 2014 21:18:18 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, "samix.lebsir" <samix.lebsir@...el.com>,
	Alan Cox <alan@...ux.intel.com>,
	Ben Hutchings <ben@...adent.org.uk>,
	Rui Xiang <rui.xiang@...wei.com>
Subject: [PATCH 3.4 135/214] char: n_gsm: remove message filtering for contipated DLCI

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "samix.lebsir" <samix.lebsir@...el.com>

commit 10c6c383e43565c9c6ec07ff8eb2825f8091bdf0 upstream.

The design of uplink flow control in the mux driver is
that for constipated channels data will backup into the
per-channel fifos, and any messages that make it to the
outbound message queue will still go out.
Code was added to also stop messages that were in the outbound
queue but this requires filtering through all the messages on the
queue for stopped dlcis and changes some of the mux logic unneccessarily.

The message fiiltering was removed to be in line w/ the original design
as the message filtering does not provide any solution.
Extra debug messages used during investigation were also removed.

Signed-off-by: samix.lebsir <samix.lebsir@...el.com>
Signed-off-by: Alan Cox <alan@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Cc: Rui Xiang <rui.xiang@...wei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/tty/n_gsm.c |   25 +------------------------
 1 file changed, 1 insertion(+), 24 deletions(-)

--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -691,10 +691,6 @@ static void gsm_data_kick(struct gsm_mux
 			msg = msg->next;
 			continue;
 		}
-		if (gsm->dlci[msg->addr]->constipated) {
-			msg = msg->next;
-			continue;
-		}
 		if (gsm->encoding != 0) {
 			gsm->txframe[0] = GSM1_SOF;
 			len = gsm_stuff_frame(msg->data,
@@ -748,8 +744,6 @@ static void __gsm_data_queue(struct gsm_
 	u8 *dp = msg->data;
 	u8 *fcs = dp + msg->len;
 
-	WARN_ONCE(dlci->constipated, "%s: queueing from a constipated DLCI",
-		__func__);
 	/* Fill in the header */
 	if (gsm->encoding == 0) {
 		if (msg->len < 128)
@@ -959,9 +953,6 @@ static void gsm_dlci_data_sweep(struct g
 			break;
 		dlci = gsm->dlci[i];
 		if (dlci == NULL || dlci->constipated) {
-			if (dlci && (debug & 0x20))
-				pr_info("%s: DLCI %d is constipated",
-					__func__, i);
 			i++;
 			continue;
 		}
@@ -991,12 +982,8 @@ static void gsm_dlci_data_kick(struct gs
 	unsigned long flags;
 	int sweep;
 
-	if (dlci->constipated) {
-		if (debug & 0x20)
-			pr_info("%s: DLCI %d is constipated",
-				__func__, dlci->addr);
+	if (dlci->constipated)
 		return;
-	}
 
 	spin_lock_irqsave(&dlci->gsm->tx_lock, flags);
 	/* If we have nothing running then we need to fire up */
@@ -1072,15 +1059,9 @@ static void gsm_process_modem(struct tty
 	/* Flow control/ready to communicate */
 	fc = (modem & MDM_FC) || !(modem & MDM_RTR);
 	if (fc && !dlci->constipated) {
-		if (debug & 0x20)
-			pr_info("%s: DLCI %d START constipated (tx_bytes=%d)",
-				__func__, dlci->addr, dlci->gsm->tx_bytes);
 		/* Need to throttle our output on this device */
 		dlci->constipated = 1;
 	} else if (!fc && dlci->constipated) {
-		if (debug & 0x20)
-			pr_info("%s: DLCI %d END constipated (tx_bytes=%d)",
-				__func__, dlci->addr, dlci->gsm->tx_bytes);
 		dlci->constipated = 0;
 		gsm_dlci_data_kick(dlci);
 	}
@@ -1257,8 +1238,6 @@ static void gsm_control_message(struct g
 		break;
 	case CMD_FCON:
 		/* Modem can accept data again */
-		if (debug & 0x20)
-			pr_info("%s: GSM END constipation", __func__);
 		gsm->constipated = 0;
 		gsm_control_reply(gsm, CMD_FCON, NULL, 0);
 		/* Kick the link in case it is idling */
@@ -1268,8 +1247,6 @@ static void gsm_control_message(struct g
 		break;
 	case CMD_FCOFF:
 		/* Modem wants us to STFU */
-		if (debug & 0x20)
-			pr_info("%s: GSM START constipation", __func__);
 		gsm->constipated = 1;
 		gsm_control_reply(gsm, CMD_FCOFF, NULL, 0);
 		break;


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