[NET]: Fix locking in shaper driver.
o use a semaphore instead of an opencoded and racy lock o move locking out of shaper_kick and into the callers - most just released the lock before calling shaper_kick o remove in_interrupt() tests. from ->close we can always block, from ->hard_start_xmit and timer context never Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Christoph Hellwig
David S. Miller
parent
4fef0304ee
commit
b597ef4712
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@ -100,35 +100,8 @@ static int sh_debug; /* Debug flag */
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#define SHAPER_BANNER "CymruNet Traffic Shaper BETA 0.04 for Linux 2.1\n"
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/*
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* Locking
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*/
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static int shaper_lock(struct shaper *sh)
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{
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/*
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* Lock in an interrupt must fail
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*/
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while (test_and_set_bit(0, &sh->locked))
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{
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if (!in_interrupt())
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sleep_on(&sh->wait_queue);
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else
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return 0;
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}
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return 1;
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}
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static void shaper_kick(struct shaper *sh);
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static void shaper_unlock(struct shaper *sh)
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{
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clear_bit(0, &sh->locked);
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wake_up(&sh->wait_queue);
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shaper_kick(sh);
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}
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/*
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* Compute clocks on a buffer
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*/
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@ -157,17 +130,15 @@ static void shaper_setspeed(struct shaper *shaper, int bitspersec)
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* Throw a frame at a shaper.
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*/
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static int shaper_qframe(struct shaper *shaper, struct sk_buff *skb)
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static int shaper_start_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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struct shaper *shaper = dev->priv;
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struct sk_buff *ptr;
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/*
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* Get ready to work on this shaper. Lock may fail if its
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* an interrupt and locked.
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*/
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if(!shaper_lock(shaper))
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return -1;
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if (down_trylock(&shaper->sem))
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return -1;
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ptr=shaper->sendq.prev;
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/*
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@ -260,7 +231,8 @@ static int shaper_qframe(struct shaper *shaper, struct sk_buff *skb)
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dev_kfree_skb(ptr);
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shaper->stats.collisions++;
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}
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shaper_unlock(shaper);
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shaper_kick(shaper);
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up(&shaper->sem);
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return 0;
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}
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@ -297,8 +269,13 @@ static void shaper_queue_xmit(struct shaper *shaper, struct sk_buff *skb)
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static void shaper_timer(unsigned long data)
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{
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struct shaper *sh=(struct shaper *)data;
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shaper_kick(sh);
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struct shaper *shaper = (struct shaper *)data;
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if (!down_trylock(&shaper->sem)) {
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shaper_kick(shaper);
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up(&shaper->sem);
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} else
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mod_timer(&shaper->timer, jiffies);
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}
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/*
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@ -310,19 +287,6 @@ static void shaper_kick(struct shaper *shaper)
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{
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struct sk_buff *skb;
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/*
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* Shaper unlock will kick
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*/
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if (test_and_set_bit(0, &shaper->locked))
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{
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if(sh_debug)
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printk("Shaper locked.\n");
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mod_timer(&shaper->timer, jiffies);
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return;
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}
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/*
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* Walk the list (may be empty)
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*/
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@ -364,8 +328,6 @@ static void shaper_kick(struct shaper *shaper)
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if(skb!=NULL)
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mod_timer(&shaper->timer, SHAPERCB(skb)->shapeclock);
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clear_bit(0, &shaper->locked);
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}
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@ -376,14 +338,12 @@ static void shaper_kick(struct shaper *shaper)
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static void shaper_flush(struct shaper *shaper)
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{
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struct sk_buff *skb;
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if(!shaper_lock(shaper))
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{
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printk(KERN_ERR "shaper: shaper_flush() called by an irq!\n");
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return;
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}
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down(&shaper->sem);
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while((skb=skb_dequeue(&shaper->sendq))!=NULL)
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dev_kfree_skb(skb);
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shaper_unlock(shaper);
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shaper_kick(shaper);
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up(&shaper->sem);
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}
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/*
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@ -426,13 +386,6 @@ static int shaper_close(struct net_device *dev)
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* ARP and other resolutions and not before.
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*/
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static int shaper_start_xmit(struct sk_buff *skb, struct net_device *dev)
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{
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struct shaper *sh=dev->priv;
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return shaper_qframe(sh, skb);
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}
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static struct net_device_stats *shaper_get_stats(struct net_device *dev)
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{
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struct shaper *sh=dev->priv;
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@ -623,7 +576,6 @@ static void shaper_init_priv(struct net_device *dev)
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init_timer(&sh->timer);
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sh->timer.function=shaper_timer;
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sh->timer.data=(unsigned long)sh;
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init_waitqueue_head(&sh->wait_queue);
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}
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/*
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@ -23,7 +23,7 @@ struct shaper
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__u32 shapeclock;
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unsigned long recovery; /* Time we can next clock a packet out on
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an empty queue */
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unsigned long locked;
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struct semaphore sem;
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struct net_device_stats stats;
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struct net_device *dev;
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int (*hard_start_xmit) (struct sk_buff *skb,
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@ -38,7 +38,6 @@ struct shaper
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int (*hard_header_cache)(struct neighbour *neigh, struct hh_cache *hh);
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void (*header_cache_update)(struct hh_cache *hh, struct net_device *dev, unsigned char * haddr);
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struct net_device_stats* (*get_stats)(struct net_device *dev);
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wait_queue_head_t wait_queue;
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struct timer_list timer;
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};
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