On Thu, Apr 11, 2013 at 11:28:06AM +0930, Rusty Russell wrote:
Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> writes:
On Tue, Apr 09, 2013 at 01:22:09PM +0200, Veaceslav Falico wrote:
Add a new function, kset_obj_exists(), which is identical to
kset_find_obj() but doesn't take a reference to the kobject
found and only returns bool if found/not found.
The main purpose would be to avoid the possible race scenario,
when we could get the reference in between the kref_put() and
kobject_release() functions (i.e. kref_put() already ran,
refcount became 0, but the kobject_release() function still
didn't run, and we try to get via kobject_get() and thus ending
up with a released kobject). It can be triggered, for example,
by running insmod/rmmod bonding in parallel, which ends up in
a race between kset_obj_find() in mod_sysfs_init() and rmmod's
mod_sysfs_fini()/kobject_put().
As Rusty points out, this isn't a kobject issue that can be solved with
a new api call, but rather, the user of the kobject code needs to be
fixed, with something like his proposed patch instead.
So, because of this, I can't take this patch, sorry.
Greg, I'm shocked! Surely you've been doing this long enough to know
that we don't use that kind of language on lkml?
To restore the list's reputation as a hostile pressure cooker powered by
the smouldering remains of flame-roasted newcomers, allow me to correct
your reply:
"NAK. And you smell."
Got it :). Thank you for your input and your patch, I'll come back with a
proper fix when I'll have one.
Thanks all.
Crisis averted,
Rusty.
PS. Thanks :)
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