linux-kernel - Re: [PATCH 5/8] staging: vme: add functions for bridge module refcounting

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 9 Aug 2011 14:49:44 -0400
From:	"Emilio G. Cota" <cota@...ap.org>
To:	Martyn Welch <martyn.welch@...com>
Cc:	gregkh@...e.de, devel@...verdev.osuosl.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/8] staging: vme: add functions for bridge module
 refcounting

On Tue, Aug 09, 2011 at 15:26:09 +0100, Martyn Welch wrote:
> On 09/08/11 14:24, Manohar Vanga wrote:
> > If we really don't want explicit module refcounting by drivers, can we perhaps use
> > the return value of the probe to automatically do this? eg. in vme_bus_probe() like
> > below:
> > 
> >     int ret = 0;
> >     ...
> >     vme_bridge_get(bridge);
> >     if (driver->probe)
> >             ret = driver->probe(vdev);
> >     if (ret)
> >         vme_bridge_put(bridge);
> >     return ret;
> > 
> > Just a thought. Feel free to shoot it down if you think it's the incorrect
> > approach :P
> > 
> 
> After looking at the PCI and RapidIO subsystems, I think this is probably the
> correct approach. I guess the only quiestion then is at which point is
> vme_bridge_put() called assuming the probe is successful. I guess at module
> unload time, though I haven't checked in the PCI and RapidIO code.

This works as long as all devices are tied to the driver
loading; i.e. when the devices can only be removed when the
driver is removed.  A device might go away while the driver
still manages other devices of the same kin; this is why
particular drivers explicitly manage the get/put in
.probe/.release.

In vme we may one day have hotplug (VME64x supports it IIRC),
but we're not quite there yet. One can remove devices from
sysfs anytime though.

I still think the original patch is the sane way to go.

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