From: Rusty Russell <rusty@rustcorp.com.au>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Greg KH <greg@kroah.com>,
Cornelia Huck <cornelia.huck@de.ibm.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Tejun Heo <htejun@gmail.com>
Subject: Re: [Patch -mm 3/3] RFC: Introduce kobject->owner for refcounting.
Date: Tue, 17 Apr 2007 12:53:10 +1000 [thread overview]
Message-ID: <1176778391.14322.273.camel@localhost.localdomain> (raw)
In-Reply-To: <Pine.LNX.4.44L0.0704161539110.2685-100000@iolanthe.rowland.org>
On Mon, 2007-04-16 at 15:53 -0400, Alan Stern wrote:
> The fundamental rule is that whenever you hand out a pointer to a routine
> living in a module, the receiver has to increment the module's refcount.
> But the driver core violates this rule all over the place.
Hi Alan,
Your rule is overly simplistic, unfortunately. You have two choices:
take a reference count, *or* ensure that the reference will go away when
the module's cleanup routine is called. Network drivers are a classic
example of the latter.
Note that you cannot do both: if the cleanup routine calls something
which drops a reference count, it implies that the cleanup routine needs
to be called with non-zero reference count, and it won't be (ignoring
--force).
I hope that clarifies?
Rusty.
next prev parent reply other threads:[~2007-04-17 2:53 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-04-16 17:36 Cornelia Huck
2007-04-16 18:05 ` Greg KH
2007-04-16 19:53 ` Alan Stern
2007-04-17 2:53 ` Rusty Russell [this message]
2007-04-17 7:16 ` Cornelia Huck
2007-04-17 16:08 ` Alan Stern
2007-04-17 23:55 ` Rusty Russell
2007-04-18 15:20 ` Alan Stern
2007-04-19 0:46 ` Rusty Russell
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