Re: [PATCH tip/core/rcu 01/12] rcu: Remove rcu_swap_protected()

[Matthias Brugger]

On 11/12/2019 19:37, Paul E. McKenney wrote:
> On Tue, Dec 10, 2019 at 07:51:22PM -0800, Paul E. McKenney wrote:
>> On Tue, Dec 10, 2019 at 10:35:49PM -0500, Martin K. Petersen wrote:
>>>
>>> Paul,
>>>
>>>> Now that the calls to rcu_swap_protected() have been replaced by
>>>> rcu_replace_pointer(), this commit removes rcu_swap_protected().
>>>
>>> It appears there are two callers remaining in Linus' master. Otherwise
>>> looks good to me.
>>
>> I did queue a fix for one of them, and thank you for calling my
>> attention to the new one.  This commit should hit -next soon, so
>> hopefully this will discourage further additions.  ;-)
>>
>>> Reviewed-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
>>
>> Thank you!
> 
> And here is the patch for the new one.
> 
> 							Thanx, Paul
> 
> ------------------------------------------------------------------------
> 
> commit 10699d92c906707d679e28b099cd798a519b4f51
> Author: Paul E. McKenney <paulmck@xxxxxxxxxx>
> Date:   Wed Dec 11 10:30:21 2019 -0800
> 
>     wireless/mediatek: Replace rcu_swap_protected() with rcu_replace_pointer()
>     
>     This commit replaces the use of rcu_swap_protected() with the more
>     intuitively appealing rcu_replace_pointer() as a step towards removing
>     rcu_swap_protected().
>     
>     Link: https://lore.kernel.org/lkml/CAHk-=wiAsJLw1egFEE=Z7-GGtM6wcvtyytXZA1+BHqta4gg6Hw@xxxxxxxxxxxxxx/
>     Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
>     Reported-by: "Martin K. Petersen" <martin.petersen@xxxxxxxxxx>
>     Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
>     Cc: Felix Fietkau <nbd@xxxxxxxx>
>     Cc: Lorenzo Bianconi <lorenzo.bianconi83@xxxxxxxxx>
>     Cc: Ryder Lee <ryder.lee@xxxxxxxxxxxx>
>     Cc: Roy Luo <royluo@xxxxxxxxxx>
>     Cc: Kalle Valo <kvalo@xxxxxxxxxxxxxx>
>     Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
>     Cc: Matthias Brugger <matthias.bgg@xxxxxxxxx>
>     Cc: <linux-wireless@xxxxxxxxxxxxxxx>
>     Cc: <netdev@xxxxxxxxxxxxxxx>
>     Cc: <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>
>     Cc: <linux-mediatek@xxxxxxxxxxxxxxxxxxx>
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/agg-rx.c b/drivers/net/wireless/mediatek/mt76/agg-rx.c
> index 53b5a4b..80986ce 100644
> --- a/drivers/net/wireless/mediatek/mt76/agg-rx.c
> +++ b/drivers/net/wireless/mediatek/mt76/agg-rx.c
> @@ -281,8 +281,8 @@ void mt76_rx_aggr_stop(struct mt76_dev *dev, struct mt76_wcid *wcid, u8 tidno)
>  {
>  	struct mt76_rx_tid *tid = NULL;
>  
> -	rcu_swap_protected(wcid->aggr[tidno], tid,
> -			   lockdep_is_held(&dev->mutex));
> +	tid = rcu_swap_protected(wcid->aggr[tidno], tid,
> +				 lockdep_is_held(&dev->mutex));

I suppose you meant: rcu_replace_pointer() here.

Regards,
Matthias

>  	if (tid) {
>  		mt76_rx_aggr_shutdown(dev, tid);
>  		kfree_rcu(tid, rcu_head);
>