CAPI: Use tty_port to keep track of capiminor's tty

Use the reference management features of tty_port to look up and drop
again the tty_struct associated with a capiminor.

Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 62 insertions, 32 deletions

diff --git a/drivers/isdn/capi/capi.c b/drivers/isdn/capi/capi.c
index 3e4997ac67a..e164a8fb969 100644
--- a/drivers/isdn/capi/capi.c
+++ b/drivers/isdn/capi/capi.c
@@ -94,7 +94,7 @@ struct capiminor {
         u16              datahandle;
         u16              msgid;
 
-        struct tty_struct *tty;
+        struct tty_port port;
         int                ttyinstop;
         int                ttyoutstop;
         struct sk_buff    *ttyskb;
@@ -212,6 +212,8 @@ static void capiminor_del_all_ack(struct capiminor *mp)
 
 /* -------- struct capiminor ---------------------------------------- */
 
+static const struct tty_port_operations capiminor_port_ops; /* we have none */
+
 static struct capiminor *capiminor_alloc(struct capi20_appl *ap, u32 ncci)
 {
         struct capiminor *mp;
@@ -237,6 +239,9 @@ static struct capiminor *capiminor_alloc(struct capi20_appl *ap, u32 ncci)
         skb_queue_head_init(&mp->inqueue);
         skb_queue_head_init(&mp->outqueue);
 
+        tty_port_init(&mp->port);
+        mp->port.ops = &capiminor_port_ops;
+
         /* Allocate the least unused minor number. */
         write_lock_irqsave(&capiminors_lock, flags);
         for (minor = 0; minor < capi_ttyminors; minor++)
@@ -335,18 +340,22 @@ static void capincci_alloc_minor(struct capidev *cdev, struct capincci *np)
 static void capincci_free_minor(struct capincci *np)
 {
         struct capiminor *mp = np->minorp;
+        struct tty_struct *tty;
 
         if (mp) {
                 capifs_free_ncci(mp->capifs_dentry);
-                if (mp->tty) {
+
+                tty = tty_port_tty_get(&mp->port);
+                if (tty) {
                         mp->nccip = NULL;
 #ifdef _DEBUG_REFCOUNT
                         printk(KERN_DEBUG "reset mp->nccip\n");
 #endif
-                        tty_hangup(mp->tty);
-                } else {
-                        capiminor_free(mp);
+                        tty_hangup(tty);
+                        tty_kref_put(tty);
                 }
+
+                capiminor_free(mp);
         }
 }
 
@@ -433,44 +442,48 @@ gen_data_b3_resp_for(struct capiminor *mp, struct sk_buff *skb)
 
 static int handle_recv_skb(struct capiminor *mp, struct sk_buff *skb)
 {
+        struct tty_struct *tty;
         struct sk_buff *nskb;
         int datalen;
         u16 errcode, datahandle;
         struct tty_ldisc *ld;
-        
+        int ret = -1;
+
         datalen = skb->len - CAPIMSG_LEN(skb->data);
-        if (mp->tty == NULL)
-        {
+
+        tty = tty_port_tty_get(&mp->port);
+        if (!tty) {
 #ifdef _DEBUG_DATAFLOW
                 printk(KERN_DEBUG "capi: currently no receiver\n");
 #endif
                 return -1;
         }
         
-        ld = tty_ldisc_ref(mp->tty);
-        if (ld == NULL)
-                return -1;
+        ld = tty_ldisc_ref(tty);
+        if (!ld)
+                goto out1;
+
         if (ld->ops->receive_buf == NULL) {
 #if defined(_DEBUG_DATAFLOW) || defined(_DEBUG_TTYFUNCS)
                 printk(KERN_DEBUG "capi: ldisc has no receive_buf function\n");
 #endif
-                goto bad;
+                goto out2;
         }
         if (mp->ttyinstop) {
 #if defined(_DEBUG_DATAFLOW) || defined(_DEBUG_TTYFUNCS)
                 printk(KERN_DEBUG "capi: recv tty throttled\n");
 #endif
-                goto bad;
+                goto out2;
         }
-        if (mp->tty->receive_room < datalen) {
+        if (tty->receive_room < datalen) {
 #if defined(_DEBUG_DATAFLOW) || defined(_DEBUG_TTYFUNCS)
                 printk(KERN_DEBUG "capi: no room in tty\n");
 #endif
-                goto bad;
+                goto out2;
         }
         if ((nskb = gen_data_b3_resp_for(mp, skb)) == NULL) {
                 printk(KERN_ERR "capi: gen_data_b3_resp failed\n");
-                goto bad;
+                goto out2;
         }
         datahandle = CAPIMSG_U16(skb->data,CAPIMSG_BASELEN+4);
         errcode = capi20_put_message(mp->ap, nskb);
@@ -478,20 +491,21 @@ static int handle_recv_skb(struct capiminor *mp, struct sk_buff *skb)
                 printk(KERN_ERR "capi: send DATA_B3_RESP failed=%x\n",
                                 errcode);
                 kfree_skb(nskb);
-                goto bad;
+                goto out2;
         }
         (void)skb_pull(skb, CAPIMSG_LEN(skb->data));
 #ifdef _DEBUG_DATAFLOW
         printk(KERN_DEBUG "capi: DATA_B3_RESP %u len=%d => ldisc\n",
                                 datahandle, skb->len);
 #endif
-        ld->ops->receive_buf(mp->tty, skb->data, NULL, skb->len);
+        ld->ops->receive_buf(tty, skb->data, NULL, skb->len);
         kfree_skb(skb);
+        ret = 0;
+out2:
         tty_ldisc_deref(ld);
-        return 0;
-bad:
-        tty_ldisc_deref(ld);
-        return -1;
+out1:
+        tty_kref_put(tty);
+        return ret;
 }
 
 static void handle_minor_recv(struct capiminor *mp)
@@ -510,16 +524,22 @@ static void handle_minor_recv(struct capiminor *mp)
 
 static int handle_minor_send(struct capiminor *mp)
 {
+        struct tty_struct *tty;
         struct sk_buff *skb;
         u16 len;
         int count = 0;
         u16 errcode;
         u16 datahandle;
 
-        if (mp->tty && mp->ttyoutstop) {
+        tty = tty_port_tty_get(&mp->port);
+        if (!tty)
+                return 0;
+
+        if (mp->ttyoutstop) {
 #if defined(_DEBUG_DATAFLOW) || defined(_DEBUG_TTYFUNCS)
                 printk(KERN_DEBUG "capi: send: tty stopped\n");
 #endif
+                tty_kref_put(tty);
                 return 0;
         }
 
@@ -542,6 +562,7 @@ static int handle_minor_send(struct capiminor *mp)
                 if (capiminor_add_ack(mp, datahandle) < 0) {
                         skb_pull(skb, CAPI_DATA_B3_REQ_LEN);
                         skb_queue_head(&mp->outqueue, skb);
+                        tty_kref_put(tty);
                         return count;
                 }
                 errcode = capi20_put_message(mp->ap, skb);
@@ -568,6 +589,7 @@ static int handle_minor_send(struct capiminor *mp)
                 mp->outbytes -= len;
                 kfree_skb(skb);
         }
+        tty_kref_put(tty);
         return count;
 }
 
@@ -578,6 +600,7 @@ static void capi_recv_message(struct capi20_appl *ap, struct sk_buff *skb)
 {
         struct capidev *cdev = ap->private;
 #ifdef CONFIG_ISDN_CAPI_MIDDLEWARE
+        struct tty_struct *tty;
         struct capiminor *mp;
         u16 datahandle;
 #endif /* CONFIG_ISDN_CAPI_MIDDLEWARE */
@@ -641,8 +664,11 @@ static void capi_recv_message(struct capi20_appl *ap, struct sk_buff *skb)
 #endif
                 kfree_skb(skb);
                 (void)capiminor_del_ack(mp, datahandle);
-                if (mp->tty)
-                        tty_wakeup(mp->tty);
+                tty = tty_port_tty_get(&mp->port);
+                if (tty) {
+                        tty_wakeup(tty);
+                        tty_kref_put(tty);
+                }
                 (void)handle_minor_send(mp);
 
         } else {
@@ -1029,14 +1055,17 @@ static void capinc_tty_cleanup(struct tty_struct *tty)
         capiminor_put(mp);
 }
 
-static int capinc_tty_open(struct tty_struct * tty, struct file * file)
+static int capinc_tty_open(struct tty_struct *tty, struct file *filp)
 {
         struct capiminor *mp = tty->driver_data;
         unsigned long flags;
+        int err;
+
+        err = tty_port_open(&mp->port, tty, filp);
+        if (err)
+                return err;
 
         spin_lock_irqsave(&workaround_lock, flags);
-        if (atomic_read(&mp->ttyopencount) == 0)
-                mp->tty = tty;
         atomic_inc(&mp->ttyopencount);
 #ifdef _DEBUG_REFCOUNT
         printk(KERN_DEBUG "capinc_tty_open ocount=%d\n", atomic_read(&mp->ttyopencount));
@@ -1046,7 +1075,7 @@ static int capinc_tty_open(struct tty_struct * tty, struct file * file)
         return 0;
 }
 
-static void capinc_tty_close(struct tty_struct * tty, struct file * file)
+static void capinc_tty_close(struct tty_struct *tty, struct file *filp)
 {
         struct capiminor *mp = tty->driver_data;
 
@@ -1054,17 +1083,15 @@ static void capinc_tty_close(struct tty_struct * tty, struct file * file)
 #ifdef _DEBUG_REFCOUNT
                         printk(KERN_DEBUG "capinc_tty_close lastclose\n");
 #endif
-                        mp->tty = NULL;
                 }
 #ifdef _DEBUG_REFCOUNT
                 printk(KERN_DEBUG "capinc_tty_close ocount=%d\n", atomic_read(&mp->ttyopencount));
 #endif
-                if (mp->nccip == NULL)
-                        capiminor_free(mp);
 
 #ifdef _DEBUG_REFCOUNT
         printk(KERN_DEBUG "capinc_tty_close\n");
 #endif
+        tty_port_close(&mp->port, tty, filp);
 }
 
 static int capinc_tty_write(struct tty_struct * tty,
@@ -1292,9 +1319,12 @@ static void capinc_tty_start(struct tty_struct *tty)
 
 static void capinc_tty_hangup(struct tty_struct *tty)
 {
+        struct capiminor *mp = tty->driver_data;
+
 #ifdef _DEBUG_TTYFUNCS
         printk(KERN_DEBUG "capinc_tty_hangup\n");
 #endif
+        tty_port_hangup(&mp->port);
 }
 
 static int capinc_tty_break_ctl(struct tty_struct *tty, int state)