Commit 3f3ebe53 authored by Stephen Hemminger's avatar Stephen Hemminger Committed by Paolo Abeni
Browse files

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: default avatarStephen Hemminger <stephen@networkplumber.org>
Reviewed-by: default avatarWillem de Bruijn <willemb@google.com>
Acked-by: default avatarJason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20240126002550.169608-1-stephen@networkplumber.org


Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent e8166eb2

drivers/net/tun.c

+3 −4
Original line number Diff line number Diff line
@@ -54,6 +54,7 @@ 
#include <linux/if_tun.h>

#include <linux/if_vlan.h>

#include <linux/crc32.h>

#include <linux/math.h>

#include <linux/nsproxy.h>

#include <linux/virtio_net.h>

#include <linux/rcupdate.h>
@@ -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;