On Thu, 2008-09-11 at 19:39 +0200, Johannes Berg wrote:
> Well take the larger bit of code:
>
> struct something *an = NULL;
>
> ...
>
> rcu_read_lock();
> sta = ieee80211_find_sta(hw, hdr->addr2);
> if (sta)
> an = (void *) sta->drv_priv;
>
> if (an) {
> ath_rx_input(sc, an,
> hw->conf.ht_conf.ht_supported,
> skb, status, &st);
> }
> rcu_read_unlock();
>
> /* the "!an" here is fine even outside RCU lock */
> if (!an || (st != ATH_RX_CONSUMED))
> __ieee80211_rx(hw, skb, &rx_status);
>
>
> So at this point it's only checking whether above it had a pointer, it's
> not accessing it. Think of the "an" variable, after rcu_read_unlock(),
> as a bool indicating whether or not the code that just happened had
> access to the node or not.
That said, here it's probably smarter to just initialise "st" to
something other than _RX_CONSUMED and remove that !an condition
entirely.
johannes
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