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Date: Sat, 5 Feb 2022 18:43:25 +0530
From: Mukesh Ojha <quic_mojha@...cinc.com>
To: <linux-kernel@...r.kernel.org>
CC: <peterz@...radead.org>, <tglx@...utronix.de>, <paulmck@...nel.org>,
<will@...nel.org>, <dave@...olabs.net>, <frederic@...nel.org>,
Mukesh Ojha <quic_mojha@...cinc.com>
Subject: [PATCH] softirq: Remove raise_softirq from tasklet_action_common()
Think about a scenario when all other cores are in suspend
and one core is only running ksoftirqd and it is because
some client has invoked tasklet_hi_schedule() only once
during that phase.
tasklet_action_common() handles that softirq and marks the
same softirq as pending again. And due to that core keeps
running the softirq handler [1] forever and it is not able to
go to suspend.
We can get rid of raising softirq from tasklet handler.
[1]
<idle>-0 [003] 13058.769081: softirq_entry vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13058.769085: softirq_raise: vec=0 [action=HI_SOFTIRQ]
<idle>-0 [003] 13058.769087: softirq_exit vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13058.769091: softirq_entry vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13058.769094: softirq_raise: vec=0 [action=HI_SOFTIRQ]
<idle>-0 [003] 13058.769097: softirq_exit vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13058.769100: softirq_entry vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13058.769103: softirq_raise: vec=0 [action=HI_SOFTIRQ]
<idle>-0 [003] 13058.769106: softirq_exit vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13058.769109: softirq_entry vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13059.058923: softirq_entry vec=0 action=HI_SOFTIRQ
...
..
..
..
<idle>-0 [003] 13059.058951: softirq_entry vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13059.058954: softirq_raise: vec=0 [action=HI_SOFTIRQ]
<idle>-0 [003] 13059.058957: softirq_exit vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13059.058960: softirq_entry vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13059.058963: softirq_raise: vec=0 [action=HI_SOFTIRQ]
<idle>-0 [003] 13059.058966: softirq_exit vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13059.058969: softirq_entry vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13059.058972: softirq_raise: vec=0 [action=HI_SOFTIRQ]
<idle>-0 [003] 13059.058975: softirq_exit vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13059.058978: softirq_entry vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13059.058981: softirq_raise: vec=0 [action=HI_SOFTIRQ]
<idle>-0 [003] 13059.058984: softirq_exit vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13059.058987: softirq_entry vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13059.058990: softirq_raise: vec=0 [action=HI_SOFTIRQ]
<idle>-0 [003] 13059.058993: softirq_exit vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13059.058996: softirq_entry vec=0 action=HI_SOFTIRQ
<idle>-0 [003] 13059.059000: softirq_raise: vec=0 [action=HI_SOFTIRQ]
<idle>-0 [003] 13059.059002: softirq_exit vec=0 action=HI_SOFTIRQ
Signed-off-by: Mukesh Ojha <quic_mojha@...cinc.com>
---
kernel/softirq.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 41f4709..d3e6fb9 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -795,7 +795,6 @@ static void tasklet_action_common(struct softirq_action *a,
t->next = NULL;
*tl_head->tail = t;
tl_head->tail = &t->next;
- __raise_softirq_irqoff(softirq_nr);
local_irq_enable();
}
}
--
2.7.4
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