1 files changed, 38 insertions, 25 deletions

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index daaffcfadaae..f546dfe03d29 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2136,18 +2136,6 @@ static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc)
 	/* Finish outstanding timers, making sure they are done */
 	del_timer_sync(&gsm->t2_timer);
 
-	spin_lock(&gsm_mux_lock);
-	for (i = 0; i < MAX_MUX; i++) {
-		if (gsm_mux[i] == gsm) {
-			gsm_mux[i] = NULL;
-			break;
-		}
-	}
-	spin_unlock(&gsm_mux_lock);
-	/* open failed before registering => nothing to do */
-	if (i == MAX_MUX)
-		return;
-
 	/* Free up any link layer users */
 	for (i = 0; i < NUM_DLCI; i++)
 		if (gsm->dlci[i])
@@ -2171,7 +2159,6 @@ static void gsm_cleanup_mux(struct gsm_mux *gsm, bool disc)
 static int gsm_activate_mux(struct gsm_mux *gsm)
 {
 	struct gsm_dlci *dlci;
-	int i = 0;
 
 	timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0);
 	init_waitqueue_head(&gsm->event);
@@ -2183,18 +2170,6 @@ static int gsm_activate_mux(struct gsm_mux *gsm)
 	else
 		gsm->receive = gsm1_receive;
 
-	spin_lock(&gsm_mux_lock);
-	for (i = 0; i < MAX_MUX; i++) {
-		if (gsm_mux[i] == NULL) {
-			gsm->num = i;
-			gsm_mux[i] = gsm;
-			break;
-		}
-	}
-	spin_unlock(&gsm_mux_lock);
-	if (i == MAX_MUX)
-		return -EBUSY;
-
 	dlci = gsm_dlci_alloc(gsm, 0);
 	if (dlci == NULL)
 		return -ENOMEM;
@@ -2210,6 +2185,15 @@ static int gsm_activate_mux(struct gsm_mux *gsm)
  */
 static void gsm_free_mux(struct gsm_mux *gsm)
 {
+	int i;
+
+	for (i = 0; i < MAX_MUX; i++) {
+		if (gsm == gsm_mux[i]) {
+			gsm_mux[i] = NULL;
+			break;
+		}
+	}
+	mutex_destroy(&gsm->mutex);
 	kfree(gsm->txframe);
 	kfree(gsm->buf);
 	kfree(gsm);
@@ -2229,12 +2213,20 @@ static void gsm_free_muxr(struct kref *ref)
 
 static inline void mux_get(struct gsm_mux *gsm)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&gsm_mux_lock, flags);
 	kref_get(&gsm->ref);
+	spin_unlock_irqrestore(&gsm_mux_lock, flags);
 }
 
 static inline void mux_put(struct gsm_mux *gsm)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&gsm_mux_lock, flags);
 	kref_put(&gsm->ref, gsm_free_muxr);
+	spin_unlock_irqrestore(&gsm_mux_lock, flags);
 }
 
 static inline unsigned int mux_num_to_base(struct gsm_mux *gsm)
@@ -2255,6 +2247,7 @@ static inline unsigned int mux_line_to_num(unsigned int line)
 
 static struct gsm_mux *gsm_alloc_mux(void)
 {
+	int i;
 	struct gsm_mux *gsm = kzalloc(sizeof(struct gsm_mux), GFP_KERNEL);
 	if (gsm == NULL)
 		return NULL;
@@ -2284,6 +2277,26 @@ static struct gsm_mux *gsm_alloc_mux(void)
 	gsm->mtu = 64;
 	gsm->dead = true;	/* Avoid early tty opens */
 
+	/* Store the instance to the mux array or abort if no space is
+	 * available.
+	 */
+	spin_lock(&gsm_mux_lock);
+	for (i = 0; i < MAX_MUX; i++) {
+		if (!gsm_mux[i]) {
+			gsm_mux[i] = gsm;
+			gsm->num = i;
+			break;
+		}
+	}
+	spin_unlock(&gsm_mux_lock);
+	if (i == MAX_MUX) {
+		mutex_destroy(&gsm->mutex);
+		kfree(gsm->txframe);
+		kfree(gsm->buf);
+		kfree(gsm);
+		return NULL;
+	}
+
 	return gsm;
 }