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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Sat, 27 May 2017 19:02:06 +0200
Subject: net/core: disable NET_RX_BUSY_POLL
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.2/older/patches-5.2.9-rt3.tar.xz
sk_busy_loop() does preempt_disable() followed by a few operations which can
take sleeping locks and may get long.
I _think_ that we could use preempt_disable_nort() (in sk_busy_loop()) instead
but after a successfull cmpxchg(&napi->state, …) we would gain the ressource
and could be scheduled out. At this point nobody knows who (which context) owns
it and so it could take a while until the state is realeased and napi_poll()
could be invoked again.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
net/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -280,7 +280,7 @@ config CGROUP_NET_CLASSID
config NET_RX_BUSY_POLL
bool
- default y
+ default y if !PREEMPT_RT_FULL
config BQL
bool
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