1 files changed, 34 insertions, 0 deletions
diff --git a/debian/patches-rt/net-sched-Allow-statistics-reads-from-softirq.patch b/debian/patches-rt/net-sched-Allow-statistics-reads-from-softirq.patch
new file mode 100644
index 000000000..7a5666932
--- /dev/null
+++ b/debian/patches-rt/net-sched-Allow-statistics-reads-from-softirq.patch
@@ -0,0 +1,34 @@
+From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Date: Tue, 19 Oct 2021 12:12:04 +0200
+Subject: [PATCH] net: sched: Allow statistics reads from softirq.
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.15/older/patches-5.15.3-rt21.tar.xz
+
+Eric reported that the rate estimator reads statics from the softirq
+which in turn triggers a warning introduced in the statistics rework.
+
+The warning is too cautious. The updates happen in the softirq context
+so reads from softirq are fine since the writes can not be preempted.
+The updates/writes happen during qdisc_run() which ensures one writer
+and the softirq context.
+The remaining bad context for reading statistics remains in hard-IRQ
+because it may preempt a writer.
+
+Fixes: 29cbcd8582837 ("net: sched: Remove Qdisc::running sequence counter")
+Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+ net/core/gen_stats.c |    2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/net/core/gen_stats.c
++++ b/net/core/gen_stats.c
+@@ -154,7 +154,7 @@ void gnet_stats_add_basic(struct gnet_st
+ 	u64 bytes = 0;
+ 	u64 packets = 0;
+ 
+-	WARN_ON_ONCE((cpu || running) && !in_task());
++	WARN_ON_ONCE((cpu || running) && in_hardirq());
+ 
+ 	if (cpu) {
+ 		gnet_stats_add_basic_cpu(bstats, cpu);