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net/tun: use reciprocal_scale

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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 <stephen@networkplumber.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20240126002550.169608-1-stephen@networkplumber.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Stephen Hemminger 2024-01-25 16:25:11 -08:00 committed by Paolo Abeni
parent e8166eb246
commit 3f3ebe5362
1 changed files with 3 additions and 4 deletions
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7
drivers/net/tun.c
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@ -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;