On 7/18/07, Satyam Sharma <[email protected]> wrote:
On 7/18/07, Tejun Heo <[email protected]> wrote:
> Tejun Heo wrote:
> > Satyam Sharma wrote:
> >>>> sysfs_find_dirent() -- to check for -EEXIST -- should be called
> >>>> *before* we create the new dentry for the to-be-created symlink
> >>>> in the first place. [ It's weird to grab a reference on the target
> >>>> for ourselves (and in fact even allocate the new dirent for the
> >>>> to-be-created symlink) and /then/ check for erroneous usage,
> >>>> and then go about undoing all that we should never have done
> >>>> at all. ] So this test could, and should, be made earlier, IMHO.
> >>> Locking.
> >> Well s/sysfs_find_dirent/sysfs_get_dirent/ then. And then simply put
> >> down the reference later.
> >
> > Isn't that the current code?
>
> Oops, somehow thought you were talking about allocating it first.
> Gee... what difference does using sysfs_get_dirent() make? Do you think
> the following code is correct?
>
> sd = sysfs_get_dirent("some name");
> if (sd != NULL)
> return -EEXIST;
> lock;
> add_new_node("some name");
> unlock;
> sysfs_put_dirent(sd);
Nopes, it's not, of course. We'd need the parent's i_mutex as well
as the sysfs_mutex around both the EEXIST check as well as the
actual sysfs_add_one(), which is precisely what sysfs_addrm_start
and finish are, so you're right ... I'll factor this in.
I tried to apply the patch you sent earlier, but it was rejected
(2.6.22-rc6-mm1 + Tejun's patch + your patch). When you and
Tejun agree on an additional patch, I'd be happy to test it for you.
Miles
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