From 364b6055738b4c752c30ccaaf25c624e69d76195 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Tue, 15 Nov 2016 10:15:13 -0800
Subject: [PATCH] net: busy-poll: return busypolling status to drivers
NAPI drivers use napi_complete_done() or napi_complete() when
they drained RX ring and right before re-enabling device interrupts.
In busy polling, we can avoid interrupts being delivered since
we are polling RX ring in a controlled loop.
Drivers can chose to use napi_complete_done() return value
to reduce interrupts overhead while busy polling is active.
This is optional, legacy drivers should work fine even
if not updated.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Adam Belay <abelay@google.com>
Cc: Tariq Toukan <tariqt@mellanox.com>
Cc: Yuval Mintz <Yuval.Mintz@cavium.com>
Cc: Ariel Elior <ariel.elior@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/linux/netdevice.h | 7 ++++---
net/core/dev.c | 10 ++++++----
2 files changed, 10 insertions(+), 7 deletions(-)
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index e71de66e37929..bcddf951ccee9 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -463,16 +463,17 @@ static inline bool napi_reschedule(struct napi_struct *napi)
return false;
}
-void __napi_complete(struct napi_struct *n);
-void napi_complete_done(struct napi_struct *n, int work_done);
+bool __napi_complete(struct napi_struct *n);
+bool napi_complete_done(struct napi_struct *n, int work_done);
/**
* napi_complete - NAPI processing complete
* @n: NAPI context
*
* Mark NAPI processing as complete.
* Consider using napi_complete_done() instead.
+ * Return false if device should avoid rearming interrupts.
*/
-static inline void napi_complete(struct napi_struct *n)
+static inline bool napi_complete(struct napi_struct *n)
{
return napi_complete_done(n, 0);
}
diff --git a/net/core/dev.c b/net/core/dev.c
index 369dcc8efc019..edba9efeb2e93 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4898,7 +4898,7 @@ void __napi_schedule_irqoff(struct napi_struct *n)
}
EXPORT_SYMBOL(__napi_schedule_irqoff);
-void __napi_complete(struct napi_struct *n)
+bool __napi_complete(struct napi_struct *n)
{
BUG_ON(!test_bit(NAPI_STATE_SCHED, &n->state));
@@ -4906,15 +4906,16 @@ void __napi_complete(struct napi_struct *n)
* napi_complete_done().
*/
if (unlikely(test_bit(NAPI_STATE_IN_BUSY_POLL, &n->state)))
- return;
+ return false;
list_del_init(&n->poll_list);
smp_mb__before_atomic();
clear_bit(NAPI_STATE_SCHED, &n->state);
+ return true;
}
EXPORT_SYMBOL(__napi_complete);
-void napi_complete_done(struct napi_struct *n, int work_done)
+bool napi_complete_done(struct napi_struct *n, int work_done)
{
unsigned long flags;
@@ -4926,7 +4927,7 @@ void napi_complete_done(struct napi_struct *n, int work_done)
*/
if (unlikely(n->state & (NAPIF_STATE_NPSVC |
NAPIF_STATE_IN_BUSY_POLL)))
- return;
+ return false;
if (n->gro_list) {
unsigned long timeout = 0;
@@ -4948,6 +4949,7 @@ void napi_complete_done(struct napi_struct *n, int work_done)
__napi_complete(n);
local_irq_restore(flags);
}
+ return true;
}
EXPORT_SYMBOL(napi_complete_done);
--
2.30.2