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Subject[PATCH] ATM locking fix. [Re: [PATCH] spinlock not locked when unlocking in atm_dev_register]
Hi Folks,

Some time ago I promised a patch that fixes ATM device allocation code.
Fix that Alan's got in his 2.4.19-pre2-ac3 is wrong because it just removes
locking instead of fixing it.
So here goes my patch. Tested on dual Athlon box.

Marcelo, Alan, please apply.

Patch URL:
http://bluez.sf.net/atm.patch-2.4.19-pre2.gz


--- linux/net/atm/resources.c.orig Thu Mar 7 13:56:00 2002
+++ linux/net/atm/resources.c Thu Mar 7 13:56:40 2002
@@ -32,7 +32,7 @@
{
struct atm_dev *dev;

- dev = kmalloc(sizeof(*dev),GFP_KERNEL);
+ dev = kmalloc(sizeof(*dev), GFP_ATOMIC);
if (!dev) return NULL;
memset(dev,0,sizeof(*dev));
dev->type = type;
@@ -40,32 +40,24 @@
dev->link_rate = ATM_OC3_PCR;
dev->next = NULL;

- spin_lock(&atm_dev_lock);
-
dev->prev = last_dev;

if (atm_devs) last_dev->next = dev;
else atm_devs = dev;
last_dev = dev;
- spin_unlock(&atm_dev_lock);
return dev;
}


static void free_atm_dev(struct atm_dev *dev)
{
- spin_lock (&atm_dev_lock);
-
if (dev->prev) dev->prev->next = dev->next;
else atm_devs = dev->next;
if (dev->next) dev->next->prev = dev->prev;
else last_dev = dev->prev;
kfree(dev);
-
- spin_unlock (&atm_dev_lock);
}

-
struct atm_dev *atm_find_dev(int number)
{
struct atm_dev *dev;
@@ -75,17 +67,18 @@
return NULL;
}

-
struct atm_dev *atm_dev_register(const char *type,const struct atmdev_ops
*ops,
int number,atm_dev_flags_t *flags)
{
- struct atm_dev *dev;
+ struct atm_dev *dev = NULL;
+
+ spin_lock(&atm_dev_lock);

dev = alloc_atm_dev(type);
if (!dev) {
printk(KERN_ERR "atm_dev_register: no space for dev %s\n",
type);
- return NULL;
+ goto done;
}
if (number != -1) {
if (atm_find_dev(number)) {
@@ -93,8 +86,7 @@
return NULL;
}
dev->number = number;
- }
- else {
+ } else {
dev->number = 0;
while (atm_find_dev(dev->number)) dev->number++;
}
@@ -102,20 +94,23 @@
dev->dev_data = NULL;
barrier();
dev->ops = ops;
- if (flags) dev->flags = *flags;
- else memset(&dev->flags,0,sizeof(dev->flags));
+ if (flags)
+ dev->flags = *flags;
+ else
+ memset(&dev->flags,0,sizeof(dev->flags));
memset((void *) &dev->stats,0,sizeof(dev->stats));
#ifdef CONFIG_PROC_FS
if (ops->proc_read)
if (atm_proc_dev_register(dev) < 0) {
printk(KERN_ERR "atm_dev_register: "
"atm_proc_dev_register failed for dev %s\n",type);
- spin_unlock (&atm_dev_lock);
free_atm_dev(dev);
- return NULL;
+ goto done;
}
#endif
- spin_unlock (&atm_dev_lock);
+
+done:
+ spin_unlock(&atm_dev_lock);
return dev;
}

@@ -125,10 +120,11 @@
#ifdef CONFIG_PROC_FS
if (dev->ops->proc_read) atm_proc_dev_deregister(dev);
#endif
+ spin_lock(&atm_dev_lock);
free_atm_dev(dev);
+ spin_unlock(&atm_dev_lock);
}

-
void shutdown_atm_dev(struct atm_dev *dev)
{
if (dev->vccs) {
@@ -146,7 +142,6 @@
kfree(sk->protinfo.af_atm);
}

-
struct sock *alloc_atm_vcc_sk(int family)
{
struct sock *sk;

-
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