netdev - [PATCH net] net: drv: netdevsim: don't napi

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Message-ID: <20250611174643.2769263-1-kuba@kernel.org>
Date: Wed, 11 Jun 2025 10:46:43 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: davem@...emloft.net
Cc: netdev@...r.kernel.org,
	edumazet@...gle.com,
	pabeni@...hat.com,
	andrew+netdev@...n.ch,
	horms@...nel.org,
	Jakub Kicinski <kuba@...nel.org>,
	Breno Leitao <leitao@...ian.org>,
	dw@...idwei.uk
Subject: [PATCH net] net: drv: netdevsim: don't napi_complete() from netpoll

netdevsim supports netpoll. Make sure we don't call napi_complete()
from it, since it may not be scheduled. Breno reports hitting a
warning in napi_complete_done():

WARNING: CPU: 14 PID: 104 at net/core/dev.c:6592 napi_complete_done+0x2cc/0x560
  __napi_poll+0x2d8/0x3a0
  handle_softirqs+0x1fe/0x710

This is presumably after netpoll stole the SCHED bit prematurely.

Reported-by: Breno Leitao <leitao@...ian.org>
Fixes: 3762ec05a9fb ("netdevsim: add NAPI support")
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
---
CC: dw@...idwei.uk
---
 drivers/net/netdevsim/netdev.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/netdevsim/netdev.c b/drivers/net/netdevsim/netdev.c
index af545d42961c..fa5fbd97ad69 100644
--- a/drivers/net/netdevsim/netdev.c
+++ b/drivers/net/netdevsim/netdev.c
@@ -371,7 +371,8 @@ static int nsim_poll(struct napi_struct *napi, int budget)
 	int done;
 
 	done = nsim_rcv(rq, budget);
-	napi_complete(napi);
+	if (done < budget)
+		napi_complete_done(napi, done);
 
 	return done;
 }
-- 
2.49.0