Messages in this thread | | | Date | Thu, 1 Nov 2018 14:40:02 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH v8 1/2] seccomp: add a return code to trap to userspace |
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On 10/29, Tycho Andersen wrote: > > +static struct file *init_listener(struct seccomp_filter *filter) > +{ > + struct file *ret = ERR_PTR(-EBUSY); > + struct seccomp_filter *cur, *last_locked = NULL; > + int filter_nesting = 0; > + > + for (cur = current->seccomp.filter; cur; cur = cur->prev) { > + mutex_lock_nested(&cur->notify_lock, filter_nesting); > + filter_nesting++; > + last_locked = cur; > + if (cur->notif) > + goto out; > + }
Somehow I no longer understand why do you need to take all locks. Isn't the first filter's notify_lock enough? IOW,
for (cur = current->seccomp.filter; cur; cur = cur->prev) { if (cur->notif) return ERR_PTR(-EBUSY); first = cur; }
if (first) mutex_lock(&first->notify_lock);
... initialize filter->notif ...
out: if (first) mutex_unlock(&first->notify_lock);
return ret;
Oleg.
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