From 780c568fece2cc79da920c92f876a86c07941e4e Mon Sep 17 00:00:00 2001
From: Hans Petter Selasky <hselasky@FreeBSD.org>
Date: Thu, 30 Jan 2020 12:04:02 +0000
Subject: [PATCH] Widen EPOCH(9) usage in netisr.

Software interrupt handlers are allowed to sleep. In swi_net() there
is a read lock behind NETISR_RLOCK() which in turn ends up calling
msleep() which means the whole of swi_net() cannot be protected by an
EPOCH(9) section. By default the NETISR_LOCKING feature is disabled.

This issue was introduced by r357004. This is a preparation step for
replacing the functionality provided by r357004.

Found by:	kib@
Sponsored by:	Mellanox Technologies
---
 sys/net/netisr.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sys/net/netisr.c b/sys/net/netisr.c
index f6ffb5b39bb..2322aeffadd 100644
--- a/sys/net/netisr.c
+++ b/sys/net/netisr.c
@@ -920,6 +920,7 @@ netisr_process_workstream_proto(struct netisr_workstream *nwsp, u_int proto)
 static void
 swi_net(void *arg)
 {
+	struct epoch_tracker et;
 #ifdef NETISR_LOCKING
 	struct rm_priotracker tracker;
 #endif
@@ -931,7 +932,9 @@ swi_net(void *arg)
 #ifdef DEVICE_POLLING
 	KASSERT(nws_count == 1,
 	    ("%s: device_polling but nws_count != 1", __func__));
+	NET_EPOCH_ENTER(et);
 	netisr_poll();
+	NET_EPOCH_EXIT(et);
 #endif
 #ifdef NETISR_LOCKING
 	NETISR_RLOCK(&tracker);
@@ -940,6 +943,7 @@ swi_net(void *arg)
 	KASSERT(!(nwsp->nws_flags & NWS_RUNNING), ("swi_net: running"));
 	if (nwsp->nws_flags & NWS_DISPATCHING)
 		goto out;
+	NET_EPOCH_ENTER(et);
 	nwsp->nws_flags |= NWS_RUNNING;
 	nwsp->nws_flags &= ~NWS_SCHEDULED;
 	while ((bits = nwsp->nws_pendingbits) != 0) {
@@ -950,6 +954,7 @@ swi_net(void *arg)
 		}
 	}
 	nwsp->nws_flags &= ~NWS_RUNNING;
+	NET_EPOCH_EXIT(et);
 out:
 	NWS_UNLOCK(nwsp);
 #ifdef NETISR_LOCKING