On 9.06.23 9:11, Pavel Tikhomirov wrote:
On 09.06.2023 00:19, Alexander Atanasov wrote:
Current code removes the old_delta kobject before the new delta
is ready to be used in case there is an error while reading BAT,
the "too short BAT" error we have seen.
The above sentence seems incomplete, as in an opposite case where there
was no error, old_delta kobject would have been removed before new delta
is ready anyway =)
Ok, i will try to make it clear.
.... [snip] ...
+/*
+ * Have to implement own version of kobject_rename since it is GPL
only symbol
+ */
+static int ploop_rename_delta(struct ploop_delta *delta, int level,
char *pref)
+{
+ kobject_del(&delta->kobj);
+ return KOBJECT_ADD(&delta->kobj, &delta->plo->kobj,
+ "%s%d", pref ? : "", level);
+}
+
It would probably be cleaner to put this function just before the
function using it (rename_deltas).
Ok.
... [snip] ...
-
-out_kobj_del:
- kobject_del(&delta->kobj);
kobject_put(&plo->kobj);
+ return 0;
+out_kobj_restore:
+ /* we haven't dropped our plo->kobj ref just add back */
+ err = KOBJECT_ADD(&old_delta->kobj, &plo->kobj, "%d",
old_delta->level);
+ if (err < 0) {
+ PL_ERR(plo, "Failed to restore old delta kobject\n");
+ /*
+ * Get an extra ref to parent object as kobject_add does, so it
+ * later kobject_del doesn't destory it
+ */
+ kobject_get(&plo->kobj);
Later kobject_del would not see parent object as first kobject_del did
"kobj->parent = NULL;", so in this aspect you should not be getting
reference here.
note: Problem I was talking in my previous message was about kobj->kset
put.
Yes, the problem comes from doing double kobject_put which results in
double kobj_kset_leave call which results in double kset_put.
I've missed the clearing of kobject->parent so came the idea about the
extra ref. Now i wonder would it help to take an extra ref for the
kobj->kset since there is no other way to handle the error. What do you
think about that ?
--
Regards,
Alexander Atanasov
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