Thread (7 messages) 7 messages, 2 authors, 2011-03-25

Re: [PATCH v3 3/4] genirq: Split irq_set_affinity() so it can be called with lock held

From: Thomas Gleixner <hidden>
Date: 2011-03-25 22:32:56
Also in: lkml

On Fri, 25 Mar 2011, David Daney wrote:
quoted hunk ↗ jump to hunk
The .irq_cpu_online() and .irq_cpu_offline() functions may need to
adjust affinity, but they are called with the descriptor lock held.
Create __irq_set_affinity_locked() which is called with the lock held.
Make irq_set_affinity() just a wrapper that acquires the lock.

Signed-off-by: David Daney <redacted>
---
 include/linux/interrupt.h |    2 ++
 kernel/irq/manage.c       |   40 ++++++++++++++++++++++++++--------------
 2 files changed, 28 insertions(+), 14 deletions(-)
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 59b72ca..815f9fb 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -229,6 +229,8 @@ static inline int check_wakeup_irqs(void) { return 0; }
 extern cpumask_var_t irq_default_affinity;
 
 extern int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask);
+extern int __irq_set_affinity_locked(struct irq_desc *desc,
+				     const struct cpumask *cpumask);
 extern int irq_can_set_affinity(unsigned int irq);
 extern int irq_select_affinity(unsigned int irq);
 
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 0a2aa73..3d3bed1 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -139,24 +139,12 @@ static inline void
 irq_get_pending(struct cpumask *mask, struct irq_desc *desc) { }
 #endif
 
-/**
- *	irq_set_affinity - Set the irq affinity of a given irq
- *	@irq:		Interrupt to set affinity
- *	@cpumask:	cpumask
- *
- */
-int irq_set_affinity(unsigned int irq, const struct cpumask *mask)
+
+int __irq_set_affinity_locked(struct irq_desc *desc, const struct cpumask *mask)
 {
-	struct irq_desc *desc = irq_to_desc(irq);
 	struct irq_chip *chip = desc->irq_data.chip;
-	unsigned long flags;
 	int ret = 0;
 
-	if (!chip->irq_set_affinity)
-		return -EINVAL;
We want to keep that check here. No need to crash with a NULL pointer
dereference, when we can deal with it gracefully.

Thanks,

	tglx
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