Adding debian version 6.1.76-1.debian/6.1.76-1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 108 insertions, 0 deletions

diff --git a/debian/patches-rt/0055-revert-softirq-Let-ksoftirqd-do-its-job.patch b/debian/patches-rt/0055-revert-softirq-Let-ksoftirqd-do-its-job.patch
new file mode 100644
index 000000000..c9ed7f6f6
--- /dev/null
+++ b/debian/patches-rt/0055-revert-softirq-Let-ksoftirqd-do-its-job.patch
@@ -0,0 +1,108 @@
+From fcdb9b29c6d58895a386ac23229564fad2c316b5 Mon Sep 17 00:00:00 2001
+From: Paolo Abeni <pabeni@redhat.com>
+Date: Mon, 8 May 2023 08:17:44 +0200
+Subject: [PATCH 55/62] revert: "softirq: Let ksoftirqd do its job"
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.1/older/patches-6.1.69-rt21.tar.xz
+
+Due to the mentioned commit, when the ksoftirqd processes take charge
+of softirq processing, the system can experience high latencies.
+
+In the past a few workarounds have been implemented for specific
+side-effects of the above:
+
+commit 1ff688209e2e ("watchdog: core: make sure the watchdog_worker is not deferred")
+commit 8d5755b3f77b ("watchdog: softdog: fire watchdog even if softirqs do not get to run")
+commit 217f69743681 ("net: busy-poll: allow preemption in sk_busy_loop()")
+commit 3c53776e29f8 ("Mark HI and TASKLET softirq synchronous")
+
+but the latency problem still exists in real-life workloads, see the
+link below.
+
+The reverted commit intended to solve a live-lock scenario that can now
+be addressed with the NAPI threaded mode, introduced with commit
+29863d41bb6e ("net: implement threaded-able napi poll loop support"),
+and nowadays in a pretty stable status.
+
+While a complete solution to put softirq processing under nice resource
+control would be preferable, that has proven to be a very hard task. In
+the short term, remove the main pain point, and also simplify a bit the
+current softirq implementation.
+
+Note that this change also reverts commit 3c53776e29f8 ("Mark HI and
+TASKLET softirq synchronous") and commit 1342d8080f61 ("softirq: Don't
+skip softirq execution when softirq thread is parking"), which are
+direct follow-ups of the feature commit. A single change is preferred to
+avoid known bad intermediate states introduced by a patch series
+reverting them individually.
+
+Link: https://lore.kernel.org/netdev/305d7742212cbe98621b16be782b0562f1012cb6.camel@redhat.com/
+Signed-off-by: Paolo Abeni <pabeni@redhat.com>
+Tested-by: Jason Xing <kerneljasonxing@gmail.com>
+Reviewed-by: Jakub Kicinski <kuba@kernel.org>
+Reviewed-by: Eric Dumazet <edumazet@google.com>
+Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Link: https://lore.kernel.org/r/57e66b364f1b6f09c9bc0316742c3b14f4ce83bd.1683526542.git.pabeni@redhat.com
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+(cherry picked from commit b8a04a538ed4755dc97c403ee3b8dd882955c98c)
+Signed-off-by: Clark Williams <clark.williams@gmail.com>
+---
+ kernel/softirq.c | 22 ++--------------------
+ 1 file changed, 2 insertions(+), 20 deletions(-)
+
+diff --git a/kernel/softirq.c b/kernel/softirq.c
+index 82f3e68fbe22..af9e879bbbf7 100644
+--- a/kernel/softirq.c
++++ b/kernel/softirq.c
+@@ -80,21 +80,6 @@ static void wakeup_softirqd(void)
+ 		wake_up_process(tsk);
+ }
+ 
+-/*
+- * If ksoftirqd is scheduled, we do not want to process pending softirqs
+- * right now. Let ksoftirqd handle this at its own rate, to get fairness,
+- * unless we're doing some of the synchronous softirqs.
+- */
+-#define SOFTIRQ_NOW_MASK ((1 << HI_SOFTIRQ) | (1 << TASKLET_SOFTIRQ))
+-static bool ksoftirqd_running(unsigned long pending)
+-{
+-	struct task_struct *tsk = __this_cpu_read(ksoftirqd);
+-
+-	if (pending & SOFTIRQ_NOW_MASK)
+-		return false;
+-	return tsk && task_is_running(tsk) && !__kthread_should_park(tsk);
+-}
+-
+ #ifdef CONFIG_TRACE_IRQFLAGS
+ DEFINE_PER_CPU(int, hardirqs_enabled);
+ DEFINE_PER_CPU(int, hardirq_context);
+@@ -236,7 +221,7 @@ void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
+ 		goto out;
+ 
+ 	pending = local_softirq_pending();
+-	if (!pending || ksoftirqd_running(pending))
++	if (!pending)
+ 		goto out;
+ 
+ 	/*
+@@ -432,9 +417,6 @@ static inline bool should_wake_ksoftirqd(void)
+ 
+ static inline void invoke_softirq(void)
+ {
+-	if (ksoftirqd_running(local_softirq_pending()))
+-		return;
+-
+ 	if (!force_irqthreads() || !__this_cpu_read(ksoftirqd)) {
+ #ifdef CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
+ 		/*
+@@ -468,7 +450,7 @@ asmlinkage __visible void do_softirq(void)
+ 
+ 	pending = local_softirq_pending();
+ 
+-	if (pending && !ksoftirqd_running(pending))
++	if (pending)
+ 		do_softirq_own_stack();
+ 
+ 	local_irq_restore(flags);
+-- 
+2.43.0
+