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[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>
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1 parent 4fef030 commit b597ef4712c05c962640a655386a7f06cc1a1fbc Christoph Hellwig committed with davem330 Jun 2, 2005
Showing with 20 additions and 69 deletions.
  1. +19 −67 drivers/net/shaper.c
  2. +1 −2 include/linux/if_shaper.h
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@@ -100,35 +100,8 @@ static int sh_debug; /* Debug flag */
#define SHAPER_BANNER "CymruNet Traffic Shaper BETA 0.04 for Linux 2.1\n"
-/*
- * Locking
- */
-
-static int shaper_lock(struct shaper *sh)
-{
- /*
- * Lock in an interrupt must fail
- */
- while (test_and_set_bit(0, &sh->locked))
- {
- if (!in_interrupt())
- sleep_on(&sh->wait_queue);
- else
- return 0;
-
- }
- return 1;
-}
-
static void shaper_kick(struct shaper *sh);
-static void shaper_unlock(struct shaper *sh)
-{
- clear_bit(0, &sh->locked);
- wake_up(&sh->wait_queue);
- shaper_kick(sh);
-}
-
/*
* Compute clocks on a buffer
*/
@@ -157,17 +130,15 @@ static void shaper_setspeed(struct shaper *shaper, int bitspersec)
* Throw a frame at a shaper.
*/
-static int shaper_qframe(struct shaper *shaper, struct sk_buff *skb)
+
+static int shaper_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
+ struct shaper *shaper = dev->priv;
struct sk_buff *ptr;
- /*
- * Get ready to work on this shaper. Lock may fail if its
- * an interrupt and locked.
- */
-
- if(!shaper_lock(shaper))
- return -1;
+ if (down_trylock(&shaper->sem))
+ return -1;
+
ptr=shaper->sendq.prev;
/*
@@ -260,7 +231,8 @@ static int shaper_qframe(struct shaper *shaper, struct sk_buff *skb)
dev_kfree_skb(ptr);
shaper->stats.collisions++;
}
- shaper_unlock(shaper);
+ shaper_kick(shaper);
+ up(&shaper->sem);
return 0;
}
@@ -297,8 +269,13 @@ static void shaper_queue_xmit(struct shaper *shaper, struct sk_buff *skb)
static void shaper_timer(unsigned long data)
{
- struct shaper *sh=(struct shaper *)data;
- shaper_kick(sh);
+ struct shaper *shaper = (struct shaper *)data;
+
+ if (!down_trylock(&shaper->sem)) {
+ shaper_kick(shaper);
+ up(&shaper->sem);
+ } else
+ mod_timer(&shaper->timer, jiffies);
}
/*
@@ -311,19 +288,6 @@ static void shaper_kick(struct shaper *shaper)
struct sk_buff *skb;
/*
- * Shaper unlock will kick
- */
-
- if (test_and_set_bit(0, &shaper->locked))
- {
- if(sh_debug)
- printk("Shaper locked.\n");
- mod_timer(&shaper->timer, jiffies);
- return;
- }
-
-
- /*
* Walk the list (may be empty)
*/
@@ -364,8 +328,6 @@ static void shaper_kick(struct shaper *shaper)
if(skb!=NULL)
mod_timer(&shaper->timer, SHAPERCB(skb)->shapeclock);
-
- clear_bit(0, &shaper->locked);
}
@@ -376,14 +338,12 @@ static void shaper_kick(struct shaper *shaper)
static void shaper_flush(struct shaper *shaper)
{
struct sk_buff *skb;
- if(!shaper_lock(shaper))
- {
- printk(KERN_ERR "shaper: shaper_flush() called by an irq!\n");
- return;
- }
+
+ down(&shaper->sem);
while((skb=skb_dequeue(&shaper->sendq))!=NULL)
dev_kfree_skb(skb);
- shaper_unlock(shaper);
+ shaper_kick(shaper);
+ up(&shaper->sem);
}
/*
@@ -426,13 +386,6 @@ static int shaper_close(struct net_device *dev)
* ARP and other resolutions and not before.
*/
-
-static int shaper_start_xmit(struct sk_buff *skb, struct net_device *dev)
-{
- struct shaper *sh=dev->priv;
- return shaper_qframe(sh, skb);
-}
-
static struct net_device_stats *shaper_get_stats(struct net_device *dev)
{
struct shaper *sh=dev->priv;
@@ -623,7 +576,6 @@ static void shaper_init_priv(struct net_device *dev)
init_timer(&sh->timer);
sh->timer.function=shaper_timer;
sh->timer.data=(unsigned long)sh;
- init_waitqueue_head(&sh->wait_queue);
}
/*
@@ -23,7 +23,7 @@ struct shaper
__u32 shapeclock;
unsigned long recovery; /* Time we can next clock a packet out on
an empty queue */
- unsigned long locked;
+ struct semaphore sem;
struct net_device_stats stats;
struct net_device *dev;
int (*hard_start_xmit) (struct sk_buff *skb,
@@ -38,7 +38,6 @@ struct shaper
int (*hard_header_cache)(struct neighbour *neigh, struct hh_cache *hh);
void (*header_cache_update)(struct hh_cache *hh, struct net_device *dev, unsigned char * haddr);
struct net_device_stats* (*get_stats)(struct net_device *dev);
- wait_queue_head_t wait_queue;
struct timer_list timer;
};

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