lkml.org 
[lkml]   [2020]   [Jun]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: kobject_init_and_add is easy to misuse
On Wed, Jun 03, 2020 at 01:56:20PM -0700, James Bottomley wrote:

> The store of state_in_sysfs is already done in kobject_add_internal().
> It's an existing flag people already use to tell if the kobject has
> been exposed in sysfs. However, it's set after the sysfs directory
> creation succeeds. This is the code with some debugging removed:
>
> error = create_dir(kobj);
> if (error) {
> kobj_kset_leave(kobj);
> kobject_put(parent);
> kobj->parent = NULL;
> ...
> } else
> kobj->state_in_sysfs = 1;

I was thinking most probably this will need a lock or a
smp_store_release() ..

> > It feels more robust to stick with the put though..
>
> possibly ... like I said, the only concern with the put path is that
> ->release has state expectations that aren't met if
> kobject_init_and_add fails.

Certainly error unwind bugs related to put and release will exist, but
I suspect switching to kfree won't solve them, just move them to the
next function that fails and needs a put based unwind?

At least the patches I reviewed for RDM a from Wang Hai were all
correct and didn't seem to have release based errors.

Jason

\
 
 \ /
  Last update: 2020-06-04 02:24    [W:0.341 / U:0.068 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site