On Wed, Aug 25, 2021 at 12:39 PM P Praneesh <ppranees@xxxxxxxxxxxxxx> wrote:
> Add branch prediction in dp_tx code path in
> tx and tx completion handlers.
>
> Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.4.0.1-01734-QCAHKSWPL_SILICONZ-1 v2
>
> Co-developed-by: Sriram R <srirrama@xxxxxxxxxxxxxx>
> Signed-off-by: Sriram R <srirrama@xxxxxxxxxxxxxx>
> Signed-off-by: Jouni Malinen <jouni@xxxxxxxxxxxxxx>
> Signed-off-by: P Praneesh <ppranees@xxxxxxxxxxxxxx>
> ---
> drivers/net/wireless/ath/ath11k/dp_tx.c | 45 +++++++++++++++++----------------
> drivers/net/wireless/ath/ath11k/mac.c | 2 +-
> 2 files changed, 24 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath11k/dp_tx.c b/drivers/net/wireless/ath/ath11k/dp_tx.c
> index 8bba523..ab9ccf0 100644
> --- a/drivers/net/wireless/ath/ath11k/dp_tx.c
> +++ b/drivers/net/wireless/ath/ath11k/dp_tx.c
[skipped]
> @@ -432,12 +432,12 @@ static void ath11k_dp_tx_complete_msdu(struct ath11k *ar,
>
> rcu_read_lock();
>
> - if (!rcu_dereference(ab->pdevs_active[ar->pdev_idx])) {
> + if (unlikely(!rcu_dereference(ab->pdevs_active[ar->pdev_idx]))) {
> dev_kfree_skb_any(msdu);
> goto exit;
> }
This is another place where rcu_dereference() could be replaced by the
rcu_access_pointer() and the whole block could be moved above the
rcu_read_lock().
On the other hand this is an _unlikely_ path, so it looks like a
matter of taste which macro to use here.
--
Sergey
