[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>
diff --git a/drivers/net/shaper.c b/drivers/net/shaper.c
index e68cf5f..20edeb3 100644
--- a/drivers/net/shaper.c
+++ b/drivers/net/shaper.c
@@ -100,35 +100,8 @@
#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 @@
* 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 @@
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_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 @@
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 @@
if(skb!=NULL)
mod_timer(&shaper->timer, SHAPERCB(skb)->shapeclock);
-
- clear_bit(0, &shaper->locked);
}
@@ -376,14 +338,12 @@
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 @@
* 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 @@
init_timer(&sh->timer);
sh->timer.function=shaper_timer;
sh->timer.data=(unsigned long)sh;
- init_waitqueue_head(&sh->wait_queue);
}
/*