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SubjectRe: [PATCH] 2.4.10-pre13: ATM drivers cause panic

Hello All , Isn't the linux-atm list the more appropriate list
for this discussion ? ie:

linux-atm-general@lists.sourceforge.net

The people there would definately like to know of these
discussions & troubles & fixes that are being shared .
Tia , JimL

On Mon, 24 Sep 2001, Till Immanuel Patzschke wrote:

> Hmm - patch works fine for me - no sleeps! The only spin_lock(&atm_dev_lock)
> statement in my resource.c (the original from 2.4.10-pre13) is in free_atm_dev
> BUT the problem is the unmatched spin_unlock(&atm_dev_lock) statements in
> atm_dev_register...
> Why not just protecting the atm_dev_queue in alloc_atm_dev, atm_find_dev, and
> atm_free_dev individually PLUS removing the two spin_unlock statements in
> atm_dev_register.
>
> What do you think
>
> (This is diffs from 2.4.10-pre13 ! BTW: Still the same in 2.4.10)
>
> --- resources.c.bug Fri Dec 29 23:35:47 2000
> +++ resources.c.new Mon Sep 24 11:39:42 2001
> @@ -36,13 +36,16 @@
> if (!dev) return NULL;
> memset(dev,0,sizeof(*dev));
> dev->type = type;
> - dev->prev = last_dev;
> dev->signal = ATM_PHY_SIG_UNKNOWN;
> 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;
> }
>
> @@ -65,9 +68,13 @@
> {
> struct atm_dev *dev;
>
> + spin_lock(&atm_dev_lock);
> for (dev = atm_devs; dev; dev = dev->next)
> - if (dev->ops && dev->number == number) return dev;
> - return NULL;
> + if (dev->ops && dev->number == number) goto done;
> + dev=(atm_dev *)NULL;
> + done:
> + spin_unlock(&atm_dev_lock);
> + return dev;
> }
>
>
> @@ -105,12 +112,10 @@
> 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;
> }
> #endif
> - spin_unlock (&atm_dev_lock);
> return dev;
> }
>
>
>
> Alan Cox wrote:
>
> > > seems a couple of spin_lock(s) and a spin_unlock was missing.
> > > Why didn't this problem show up with earlier releases ???
> > > Anyways, please find a (quick) patch below. It would be great if this patch or
> > > any other similar could make it into the next release!
> >
> > How about
> >
> > static struct atm_dev *alloc_atm_dev(const char *type)
> > {
> > struct atm_dev *dev;
> >
> > dev = kmalloc(sizeof(*dev),GFP_KERNEL);
> > if (!dev) return NULL;
> > memset(dev,0,sizeof(*dev));
> > dev->type = type;
> > dev->signal = ATM_PHY_SIG_UNKNOWN;
> > 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;
> > }
> >
> > instead. That seems to fix alloc_atm_dev safely. Refcounting wants adding
> > to atm_dev objects too, its impossible currently to make atm_find_dev
> > remotely safe
> >
> > Alan
>
> --
> Till Immanuel Patzschke mailto: tip@internetwork-ag.de
> interNetwork AG Phone: +49-(0)611-1731-121
> Bierstadter Str. 7 Fax: +49-(0)611-1731-31
> D-65189 Wiesbaden Web: http://www.internetwork-ag.de
>
>
>
> -
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| Network Engineer | P.O. Box 854 | Give me Linux |
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