On Thu, May 14, 2020 at 08:11:24AM -0700, Divya Indi wrote:
> static void ib_nl_set_path_rec_attrs(struct sk_buff *skb,
> struct ib_sa_query *query)
> {
> @@ -889,6 +904,15 @@ static int ib_nl_make_request(struct ib_sa_query *query,
> gfp_t gfp_mask)
> spin_lock_irqsave(&ib_nl_request_lock, flags);
> list_del(&query->list);
> spin_unlock_irqrestore(&ib_nl_request_lock, flags);
> + } else {
> + set_bit(IB_SA_NL_QUERY_SENT, (unsigned long *)&query->flags);
> +
> + /*
> + * If response is received before this flag was set
> + * someone is waiting to process the response and release the
> + * query.
> + */
> + wake_up(&wait_queue);
> }
As far as I can see the issue here is that the request is put into the
ib_nl_request_list before it is really ready to be in that list, eg
ib_nl_send_msg() has actually completed and ownership of the memory
has been transfered.
It appears to me the reason for this is simply because a spinlock is
used for the ib_nl_request_lock and it cannot be held across
ib_nl_send_msg().
Convert that lock to a mutex and move the list_add to after the
success of ib_nl_send_msg() and this bug should be fixed without
adding jaunty atomics or a wait queue.
This is a 'racy error unwind' bug class...
Jason
