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[NET]: Fix locking in shaper driver.

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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 2005-06-02 16:36:00 -07:00 committed by David S. Miller
parent 4fef0304ee
commit b597ef4712
2 changed files with 20 additions and 69 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

86
drivers/net/shaper.c
View File

@ -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);
}
/*
@ -310,19 +287,6 @@ 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);
}
/*

3
include/linux/if_shaper.h
View File

@ -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;
};