On Mon, Aug 18, 2014 at 09:29:36PM +0200, Christian Lamparter wrote:
> On Sunday, August 17, 2014 01:48:07 PM Andreea-Cristina Bernat wrote:
> > The rcu_dereference() call is used directly in a condition.
> > Since its return value is never dereferenced it is recommended to use
> > "rcu_access_pointer()" instead of "rcu_dereference()".
> > Therefore, this patch makes the replacement.
> > [...]
> > Signed-off-by: Andreea-Cristina Bernat <bernat.ada@xxxxxxxxx>
> > ---
> > drivers/net/wireless/ath/carl9170/main.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/wireless/ath/carl9170/main.c b/drivers/net/wireless/ath/carl9170/main.c
> > index f8ded84..12018ff 100644
> > --- a/drivers/net/wireless/ath/carl9170/main.c
> > +++ b/drivers/net/wireless/ath/carl9170/main.c
> > @@ -1431,7 +1431,7 @@ static int carl9170_op_ampdu_action(struct ieee80211_hw *hw,
> > return -EOPNOTSUPP;
> >
> > rcu_read_lock();
> > - if (rcu_dereference(sta_info->agg[tid])) {
> > + if (rcu_access_pointer(sta_info->agg[tid])) {
> > rcu_read_unlock();
> > return -EBUSY;
> > }
>
> There's more. The check does not do a whole lot. I think *it* [the check] and the
> rcu_read_[un]lock [and the return -EBUSY] can be removed completely from the
> IEEE80211_AMPDU_TX_START code-path in carl9170_op_ampdu_action.
>
> It would be awesome, if you could you make a patch which removes this
> unneeded cosmic-ray-protection check :-) .
Could you tell me why you think that those lines have to be removed?
I would like to fully understand this before I remove them.
Thank you,
Andreea
>
> Thanks
> Christian
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