Re: [PATCH 1/3] msi: add forgotten pci_dev_put(pdev) topopulate_msi_sysfs()

[Veaceslav Falico]

On Wed, Sep 25, 2013 at 03:30:14PM -0600, Bjorn Helgaas wrote:
> On Wed, Sep 25, 2013 at 3:08 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
> > Also, I think it is incorrect that free_msi_irqs() does this:
> >
> >                 if (entry->kobj.parent) {
> >                         kobject_del(&entry->kobj);
> >                         kobject_put(&entry->kobj);
> >                 }
> >
> >                 list_del(&entry->list);
> >                 kfree(entry);
> >
> > I think the "kfree(entry)" should be in msi_kobj_release() instead.
>
> Oh, I see you fixed this in patch 3/3.  I hadn't read that far yet :)
>
> Did you find these problems by inspection, or is there some easy way
> to trigger bad behavior?  Just wondering if this is some way I can
> reproduce the problem.

Hi,

I've first found it by building with CONFIG_DEBUG_KOBJECT_RELEASE and
CONFIG_DEBUG_OBJECTS - it shows that it's freeing an object in an active
state (I'm just running insmod/rmmod tg3 concurently, but I guess it's
reproducible with any driver that uses msi/x).

Without CONFIG_DEBUG_OBJECTS it's also reproducible, and without
CONFIG_DEBUG_KOBJECT_RELEASE it's really hard to reproduce, but still
reproducible (I've hit it with tg3 as a slave of bonding and concurently
running rmmod bonding/ifup bond0 - though it's really hard). It just panics
in kobject_put(), iirc.

So, with those CONFIG_DEBUG_* it's easily triggerable, without - quite
hard.

Hope that helps.

p.s. I'll adress your other comments tomorrow already, it's quite late here
and I don't want to do something stupid now :).

Thanks a lot!

> Bjorn
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/