CAPI: Fix locking around capiminor's output queue and drop workaround_lock
Introduce outlock as a spin lock that protects capiminor's outqueue, outbytes and outskb (formerly known as ttyskb). outlock can be acquired from soft-IRQ context via capinc_write, so make it bh-safe. This finally removes the last reason for keeping the workaround lock around (which was incomplete and partly broken anyway). And as we no longer call handle_recv_skb in atomic context, gen_data_b3_resp_for can use non-atomic allocation now. Signed-off-by: Jan Kiszka <jan.kiszka@web.de> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jan Kiszka
David S. Miller
parent
68d7347b28
commit
dfbb84ffe9
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@ -95,11 +95,13 @@ struct capiminor {
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struct tty_port port;
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int ttyinstop;
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int ttyoutstop;
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struct sk_buff *ttyskb;
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struct sk_buff_head inqueue;
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struct sk_buff_head outqueue;
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int outbytes;
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struct sk_buff_head inqueue;
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struct sk_buff_head outqueue;
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int outbytes;
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struct sk_buff *outskb;
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spinlock_t outlock;
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/* transmit path */
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struct list_head ackqueue;
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@ -107,15 +109,6 @@ struct capiminor {
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spinlock_t ackqlock;
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};
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/* FIXME: The following lock is a sledgehammer-workaround to a
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* locking issue with the capiminor (and maybe other) data structure(s).
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* Access to this data is done in a racy way and crashes the machine with
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* a FritzCard DSL driver; sooner or later. This is a workaround
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* which trades scalability vs stability, so it doesn't crash the kernel anymore.
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* The correct (and scalable) fix for the issue seems to require
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* an API change to the drivers... . */
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static DEFINE_SPINLOCK(workaround_lock);
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struct capincci {
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struct list_head list;
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u32 ncci;
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@ -231,6 +224,7 @@ static struct capiminor *capiminor_alloc(struct capi20_appl *ap, u32 ncci)
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skb_queue_head_init(&mp->inqueue);
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skb_queue_head_init(&mp->outqueue);
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spin_lock_init(&mp->outlock);
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tty_port_init(&mp->port);
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mp->port.ops = &capiminor_port_ops;
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@ -271,7 +265,7 @@ static void capiminor_destroy(struct kref *kref)
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{
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struct capiminor *mp = container_of(kref, struct capiminor, kref);
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kfree_skb(mp->ttyskb);
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kfree_skb(mp->outskb);
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skb_queue_purge(&mp->inqueue);
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skb_queue_purge(&mp->outqueue);
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capiminor_del_all_ack(mp);
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@ -417,7 +411,7 @@ static struct sk_buff *
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gen_data_b3_resp_for(struct capiminor *mp, struct sk_buff *skb)
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{
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struct sk_buff *nskb;
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nskb = alloc_skb(CAPI_DATA_B3_RESP_LEN, GFP_ATOMIC);
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nskb = alloc_skb(CAPI_DATA_B3_RESP_LEN, GFP_KERNEL);
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if (nskb) {
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u16 datahandle = CAPIMSG_U16(skb->data,CAPIMSG_BASELEN+4+4+2);
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unsigned char *s = skb_put(nskb, CAPI_DATA_B3_RESP_LEN);
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@ -548,9 +542,18 @@ static int handle_minor_send(struct capiminor *mp)
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return 0;
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}
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while ((skb = skb_dequeue(&mp->outqueue)) != NULL) {
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datahandle = atomic_inc_return(&mp->datahandle);
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while (1) {
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spin_lock_bh(&mp->outlock);
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skb = __skb_dequeue(&mp->outqueue);
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if (!skb) {
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spin_unlock_bh(&mp->outlock);
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break;
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}
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len = (u16)skb->len;
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mp->outbytes -= len;
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spin_unlock_bh(&mp->outlock);
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datahandle = atomic_inc_return(&mp->datahandle);
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skb_push(skb, CAPI_DATA_B3_REQ_LEN);
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memset(skb->data, 0, CAPI_DATA_B3_REQ_LEN);
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capimsg_setu16(skb->data, 0, CAPI_DATA_B3_REQ_LEN);
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@ -566,14 +569,18 @@ static int handle_minor_send(struct capiminor *mp)
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if (capiminor_add_ack(mp, datahandle) < 0) {
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skb_pull(skb, CAPI_DATA_B3_REQ_LEN);
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skb_queue_head(&mp->outqueue, skb);
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spin_lock_bh(&mp->outlock);
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__skb_queue_head(&mp->outqueue, skb);
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mp->outbytes += len;
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spin_unlock_bh(&mp->outlock);
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tty_kref_put(tty);
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return count;
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}
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errcode = capi20_put_message(mp->ap, skb);
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if (errcode == CAPI_NOERROR) {
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count++;
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mp->outbytes -= len;
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#ifdef _DEBUG_DATAFLOW
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printk(KERN_DEBUG "capi: DATA_B3_REQ %u len=%u\n",
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datahandle, len);
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@ -584,13 +591,17 @@ static int handle_minor_send(struct capiminor *mp)
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if (errcode == CAPI_SENDQUEUEFULL) {
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skb_pull(skb, CAPI_DATA_B3_REQ_LEN);
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skb_queue_head(&mp->outqueue, skb);
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spin_lock_bh(&mp->outlock);
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__skb_queue_head(&mp->outqueue, skb);
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mp->outbytes += len;
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spin_unlock_bh(&mp->outlock);
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break;
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}
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/* ups, drop packet */
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printk(KERN_ERR "capi: put_message = %x\n", errcode);
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mp->outbytes -= len;
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kfree_skb(skb);
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}
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tty_kref_put(tty);
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@ -609,7 +620,6 @@ static void capi_recv_message(struct capi20_appl *ap, struct sk_buff *skb)
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u16 datahandle;
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#endif /* CONFIG_ISDN_CAPI_MIDDLEWARE */
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struct capincci *np;
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unsigned long flags;
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mutex_lock(&cdev->lock);
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@ -621,7 +631,6 @@ static void capi_recv_message(struct capi20_appl *ap, struct sk_buff *skb)
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if (CAPIMSG_CMD(skb->data) == CAPI_CONNECT_B3_IND)
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capincci_alloc(cdev, CAPIMSG_NCCI(skb->data));
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spin_lock_irqsave(&workaround_lock, flags);
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if (CAPIMSG_COMMAND(skb->data) != CAPI_DATA_B3) {
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skb_queue_tail(&cdev->recvqueue, skb);
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wake_up_interruptible(&cdev->recvwait);
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@ -683,7 +692,6 @@ static void capi_recv_message(struct capi20_appl *ap, struct sk_buff *skb)
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#endif /* CONFIG_ISDN_CAPI_MIDDLEWARE */
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unlock_out:
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spin_unlock_irqrestore(&workaround_lock, flags);
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mutex_unlock(&cdev->lock);
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}
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@ -1062,16 +1070,13 @@ static void capinc_tty_cleanup(struct tty_struct *tty)
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static int capinc_tty_open(struct tty_struct *tty, struct file *filp)
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{
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struct capiminor *mp = tty->driver_data;
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unsigned long flags;
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int err;
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err = tty_port_open(&mp->port, tty, filp);
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if (err)
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return err;
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spin_lock_irqsave(&workaround_lock, flags);
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handle_minor_recv(mp);
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spin_unlock_irqrestore(&workaround_lock, flags);
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return 0;
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}
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@ -1087,71 +1092,78 @@ static int capinc_tty_write(struct tty_struct *tty,
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{
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struct capiminor *mp = tty->driver_data;
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struct sk_buff *skb;
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unsigned long flags;
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#ifdef _DEBUG_TTYFUNCS
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printk(KERN_DEBUG "capinc_tty_write(count=%d)\n", count);
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#endif
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spin_lock_irqsave(&workaround_lock, flags);
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skb = mp->ttyskb;
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spin_lock_bh(&mp->outlock);
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skb = mp->outskb;
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if (skb) {
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mp->ttyskb = NULL;
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skb_queue_tail(&mp->outqueue, skb);
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mp->outskb = NULL;
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__skb_queue_tail(&mp->outqueue, skb);
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mp->outbytes += skb->len;
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}
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skb = alloc_skb(CAPI_DATA_B3_REQ_LEN+count, GFP_ATOMIC);
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if (!skb) {
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printk(KERN_ERR "capinc_tty_write: alloc_skb failed\n");
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spin_unlock_irqrestore(&workaround_lock, flags);
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spin_unlock_bh(&mp->outlock);
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return -ENOMEM;
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}
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skb_reserve(skb, CAPI_DATA_B3_REQ_LEN);
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memcpy(skb_put(skb, count), buf, count);
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skb_queue_tail(&mp->outqueue, skb);
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__skb_queue_tail(&mp->outqueue, skb);
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mp->outbytes += skb->len;
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spin_unlock_bh(&mp->outlock);
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(void)handle_minor_send(mp);
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spin_unlock_irqrestore(&workaround_lock, flags);
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return count;
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}
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static int capinc_tty_put_char(struct tty_struct *tty, unsigned char ch)
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{
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struct capiminor *mp = tty->driver_data;
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bool invoke_send = false;
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struct sk_buff *skb;
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unsigned long flags;
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int ret = 1;
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#ifdef _DEBUG_TTYFUNCS
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printk(KERN_DEBUG "capinc_put_char(%u)\n", ch);
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#endif
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spin_lock_irqsave(&workaround_lock, flags);
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skb = mp->ttyskb;
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spin_lock_bh(&mp->outlock);
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skb = mp->outskb;
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if (skb) {
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if (skb_tailroom(skb) > 0) {
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*(skb_put(skb, 1)) = ch;
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spin_unlock_irqrestore(&workaround_lock, flags);
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return 1;
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goto unlock_out;
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}
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mp->ttyskb = NULL;
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skb_queue_tail(&mp->outqueue, skb);
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mp->outskb = NULL;
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__skb_queue_tail(&mp->outqueue, skb);
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mp->outbytes += skb->len;
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(void)handle_minor_send(mp);
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invoke_send = true;
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}
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skb = alloc_skb(CAPI_DATA_B3_REQ_LEN+CAPI_MAX_BLKSIZE, GFP_ATOMIC);
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if (skb) {
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skb_reserve(skb, CAPI_DATA_B3_REQ_LEN);
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*(skb_put(skb, 1)) = ch;
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mp->ttyskb = skb;
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mp->outskb = skb;
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} else {
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printk(KERN_ERR "capinc_put_char: char %u lost\n", ch);
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ret = 0;
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}
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spin_unlock_irqrestore(&workaround_lock, flags);
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unlock_out:
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spin_unlock_bh(&mp->outlock);
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if (invoke_send)
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(void)handle_minor_send(mp);
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return ret;
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}
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@ -1159,22 +1171,24 @@ static void capinc_tty_flush_chars(struct tty_struct *tty)
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{
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struct capiminor *mp = tty->driver_data;
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struct sk_buff *skb;
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unsigned long flags;
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#ifdef _DEBUG_TTYFUNCS
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printk(KERN_DEBUG "capinc_tty_flush_chars\n");
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#endif
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spin_lock_irqsave(&workaround_lock, flags);
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skb = mp->ttyskb;
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spin_lock_bh(&mp->outlock);
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skb = mp->outskb;
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if (skb) {
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mp->ttyskb = NULL;
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skb_queue_tail(&mp->outqueue, skb);
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mp->outskb = NULL;
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__skb_queue_tail(&mp->outqueue, skb);
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mp->outbytes += skb->len;
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spin_unlock_bh(&mp->outlock);
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(void)handle_minor_send(mp);
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}
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(void)handle_minor_recv(mp);
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spin_unlock_irqrestore(&workaround_lock, flags);
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} else
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spin_unlock_bh(&mp->outlock);
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handle_minor_recv(mp);
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}
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static int capinc_tty_write_room(struct tty_struct *tty)
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@ -1234,15 +1248,12 @@ static void capinc_tty_throttle(struct tty_struct *tty)
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static void capinc_tty_unthrottle(struct tty_struct *tty)
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{
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struct capiminor *mp = tty->driver_data;
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unsigned long flags;
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#ifdef _DEBUG_TTYFUNCS
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printk(KERN_DEBUG "capinc_tty_unthrottle\n");
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#endif
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spin_lock_irqsave(&workaround_lock, flags);
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mp->ttyinstop = 0;
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handle_minor_recv(mp);
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spin_unlock_irqrestore(&workaround_lock, flags);
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}
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static void capinc_tty_stop(struct tty_struct *tty)
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@ -1258,15 +1269,12 @@ static void capinc_tty_stop(struct tty_struct *tty)
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static void capinc_tty_start(struct tty_struct *tty)
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{
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struct capiminor *mp = tty->driver_data;
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unsigned long flags;
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#ifdef _DEBUG_TTYFUNCS
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printk(KERN_DEBUG "capinc_tty_start\n");
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#endif
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spin_lock_irqsave(&workaround_lock, flags);
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mp->ttyoutstop = 0;
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(void)handle_minor_send(mp);
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spin_unlock_irqrestore(&workaround_lock, flags);
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}
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static void capinc_tty_hangup(struct tty_struct *tty)
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