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

Matthias Brugger
2019-12-11T19:09:20Z

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 Now that the calls to rcu_swap_protected() have been replaced by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@oracle.com>
>>
>> Thank you!
>
> And here is the patch for the new one.
>
> Thanx, Paul
>
> ------------------------------------------------------------------------
>
> commit 10699d92c906707d679e28b099cd798a519b4f51
> Author: Paul E. McKenney <paulmck@kernel.org>
> 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@mail.gmail.com/
> Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
> Reported-by: "Martin K. Petersen" <martin.petersen@oracle.com>
> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> Cc: Felix Fietkau <nbd@nbd.name>
> Cc: Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>
> Cc: Ryder Lee <ryder.lee@mediatek.com>
> Cc: Roy Luo <royluo@google.com>
> Cc: Kalle Valo <kvalo@codeaurora.org>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Matthias Brugger <matthias.bgg@gmail.com>
> Cc: <linux-wireless@vger.kernel.org>
> Cc: <netdev@vger.kernel.org>
> Cc: <linux-arm-kernel@lists.infradead.org>
> Cc: <linux-mediatek@lists.infradead.org>
>
> 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);
>