From 3f3ebe53620818f6e9b029850cb47b96a4ac5b3b Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Thu, 25 Jan 2024 16:25:11 -0800 Subject: [PATCH] net/tun: use reciprocal_scale Use the inline function reciprocal_scale rather than open coding the scale optimization. Also, remove unnecessary initializations. Resulting compiled code is unchanged (according to godbolt). Signed-off-by: Stephen Hemminger Reviewed-by: Willem de Bruijn Acked-by: Jason Wang Link: https://lore.kernel.org/r/20240126002550.169608-1-stephen@networkplumber.org Signed-off-by: Paolo Abeni --- drivers/net/tun.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 4a4f8c8e79fa..e335ece47dec 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -54,6 +54,7 @@ #include #include #include +#include #include #include #include @@ -523,8 +524,7 @@ static inline void tun_flow_save_rps_rxhash(struct tun_flow_entry *e, u32 hash) static u16 tun_automq_select_queue(struct tun_struct *tun, struct sk_buff *skb) { struct tun_flow_entry *e; - u32 txq = 0; - u32 numqueues = 0; + u32 txq, numqueues; numqueues = READ_ONCE(tun->numqueues); @@ -534,8 +534,7 @@ static u16 tun_automq_select_queue(struct tun_struct *tun, struct sk_buff *skb) tun_flow_save_rps_rxhash(e, txq); txq = e->queue_index; } else { - /* use multiply and shift instead of expensive divide */ - txq = ((u64)txq * numqueues) >> 32; + txq = reciprocal_scale(txq, numqueues); } return txq;