1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
|
From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 31 Jan 2012 13:01:27 +0100
Subject: [PATCH 123/353] genirq: Allow disabling of softirq processing in irq
thread context
Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=1128442014bca498569b0b81a4f6abbb3482eb8f
The processing of softirqs in irq thread context is a performance gain
for the non-rt workloads of a system, but it's counterproductive for
interrupts which are explicitely related to the realtime
workload. Allow such interrupts to prevent softirq processing in their
thread context.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/interrupt.h | 2 ++
include/linux/irq.h | 4 +++-
kernel/irq/manage.c | 3 +++
kernel/irq/settings.h | 12 ++++++++++++
kernel/softirq.c | 9 +++++++++
5 files changed, 29 insertions(+), 1 deletion(-)
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index cf9860d49d57..e1438fe66467 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -61,6 +61,7 @@
* interrupt handler after suspending interrupts. For system
* wakeup devices users need to implement wakeup detection in
* their interrupt handlers.
+ * IRQF_NO_SOFTIRQ_CALL - Do not process softirqs in the irq thread context (RT)
*/
#define IRQF_SHARED 0x00000080
#define IRQF_PROBE_SHARED 0x00000100
@@ -74,6 +75,7 @@
#define IRQF_NO_THREAD 0x00010000
#define IRQF_EARLY_RESUME 0x00020000
#define IRQF_COND_SUSPEND 0x00040000
+#define IRQF_NO_SOFTIRQ_CALL 0x00080000
#define IRQF_TIMER (__IRQF_TIMER | IRQF_NO_SUSPEND | IRQF_NO_THREAD)
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 9504267414a4..0f1babb9775a 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -69,6 +69,7 @@ enum irqchip_irq_state;
* IRQ_IS_POLLED - Always polled by another interrupt. Exclude
* it from the spurious interrupt detection
* mechanism and from core side polling.
+ * IRQ_NO_SOFTIRQ_CALL - No softirq processing in the irq thread context (RT)
* IRQ_DISABLE_UNLAZY - Disable lazy irq disable
*/
enum {
@@ -96,13 +97,14 @@ enum {
IRQ_PER_CPU_DEVID = (1 << 17),
IRQ_IS_POLLED = (1 << 18),
IRQ_DISABLE_UNLAZY = (1 << 19),
+ IRQ_NO_SOFTIRQ_CALL = (1 << 20),
};
#define IRQF_MODIFY_MASK \
(IRQ_TYPE_SENSE_MASK | IRQ_NOPROBE | IRQ_NOREQUEST | \
IRQ_NOAUTOEN | IRQ_MOVE_PCNTXT | IRQ_LEVEL | IRQ_NO_BALANCING | \
IRQ_PER_CPU | IRQ_NESTED_THREAD | IRQ_NOTHREAD | IRQ_PER_CPU_DEVID | \
- IRQ_IS_POLLED | IRQ_DISABLE_UNLAZY)
+ IRQ_IS_POLLED | IRQ_DISABLE_UNLAZY | IRQ_NO_SOFTIRQ_CALL)
#define IRQ_NO_BALANCING_MASK (IRQ_PER_CPU | IRQ_NO_BALANCING)
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index f12f50f5b605..2bb77b0ebac8 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1533,6 +1533,9 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
irqd_set(&desc->irq_data, IRQD_NO_BALANCING);
}
+ if (new->flags & IRQF_NO_SOFTIRQ_CALL)
+ irq_settings_set_no_softirq_call(desc);
+
if (irq_settings_can_autoenable(desc)) {
irq_startup(desc, IRQ_RESEND, IRQ_START_COND);
} else {
diff --git a/kernel/irq/settings.h b/kernel/irq/settings.h
index e43795cd2ccf..47e2f9e23586 100644
--- a/kernel/irq/settings.h
+++ b/kernel/irq/settings.h
@@ -17,6 +17,7 @@ enum {
_IRQ_PER_CPU_DEVID = IRQ_PER_CPU_DEVID,
_IRQ_IS_POLLED = IRQ_IS_POLLED,
_IRQ_DISABLE_UNLAZY = IRQ_DISABLE_UNLAZY,
+ _IRQ_NO_SOFTIRQ_CALL = IRQ_NO_SOFTIRQ_CALL,
_IRQF_MODIFY_MASK = IRQF_MODIFY_MASK,
};
@@ -31,6 +32,7 @@ enum {
#define IRQ_PER_CPU_DEVID GOT_YOU_MORON
#define IRQ_IS_POLLED GOT_YOU_MORON
#define IRQ_DISABLE_UNLAZY GOT_YOU_MORON
+#define IRQ_NO_SOFTIRQ_CALL GOT_YOU_MORON
#undef IRQF_MODIFY_MASK
#define IRQF_MODIFY_MASK GOT_YOU_MORON
@@ -41,6 +43,16 @@ irq_settings_clr_and_set(struct irq_desc *desc, u32 clr, u32 set)
desc->status_use_accessors |= (set & _IRQF_MODIFY_MASK);
}
+static inline bool irq_settings_no_softirq_call(struct irq_desc *desc)
+{
+ return desc->status_use_accessors & _IRQ_NO_SOFTIRQ_CALL;
+}
+
+static inline void irq_settings_set_no_softirq_call(struct irq_desc *desc)
+{
+ desc->status_use_accessors |= _IRQ_NO_SOFTIRQ_CALL;
+}
+
static inline bool irq_settings_is_per_cpu(struct irq_desc *desc)
{
return desc->status_use_accessors & _IRQ_PER_CPU;
diff --git a/kernel/softirq.c b/kernel/softirq.c
index fd89f8ab85ac..3e9333d148ad 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -598,6 +598,15 @@ void __local_bh_enable(void)
}
EXPORT_SYMBOL(__local_bh_enable);
+void _local_bh_enable(void)
+{
+ if (WARN_ON(current->softirq_nestcnt == 0))
+ return;
+ if (--current->softirq_nestcnt == 0)
+ migrate_enable();
+}
+EXPORT_SYMBOL(_local_bh_enable);
+
int in_serving_softirq(void)
{
return current->flags & PF_IN_SOFTIRQ;
|
