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Subject[tip:irq/core] genirq: Introduce IRQD_AFFINITY_MANAGED flag
Commit-ID:  9c2555835bb3d34dfac52a0be943dcc4bedd650f
Gitweb: http://git.kernel.org/tip/9c2555835bb3d34dfac52a0be943dcc4bedd650f
Author: Thomas Gleixner <tglx@linutronix.de>
AuthorDate: Mon, 4 Jul 2016 17:39:23 +0900
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Mon, 4 Jul 2016 12:25:13 +0200

genirq: Introduce IRQD_AFFINITY_MANAGED flag

Interupts marked with this flag are excluded from user space interrupt
affinity changes. Contrary to the IRQ_NO_BALANCING flag, the kernel internal
affinity mechanism is not blocked.

This flag will be used for multi-queue device interrupts.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: linux-block@vger.kernel.org
Cc: linux-pci@vger.kernel.org
Cc: linux-nvme@lists.infradead.org
Cc: axboe@fb.com
Cc: agordeev@redhat.com
Link: http://lkml.kernel.org/r/1467621574-8277-3-git-send-email-hch@lst.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
include/linux/irq.h | 7 +++++++
kernel/irq/internals.h | 2 ++
kernel/irq/manage.c | 21 ++++++++++++++++++---
kernel/irq/proc.c | 2 +-
4 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 4d758a7..f607481 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -197,6 +197,7 @@ struct irq_data {
* IRQD_IRQ_INPROGRESS - In progress state of the interrupt
* IRQD_WAKEUP_ARMED - Wakeup mode armed
* IRQD_FORWARDED_TO_VCPU - The interrupt is forwarded to a VCPU
+ * IRQD_AFFINITY_MANAGED - Affinity is auto-managed by the kernel
*/
enum {
IRQD_TRIGGER_MASK = 0xf,
@@ -212,6 +213,7 @@ enum {
IRQD_IRQ_INPROGRESS = (1 << 18),
IRQD_WAKEUP_ARMED = (1 << 19),
IRQD_FORWARDED_TO_VCPU = (1 << 20),
+ IRQD_AFFINITY_MANAGED = (1 << 21),
};

#define __irqd_to_state(d) ACCESS_PRIVATE((d)->common, state_use_accessors)
@@ -305,6 +307,11 @@ static inline void irqd_clr_forwarded_to_vcpu(struct irq_data *d)
__irqd_to_state(d) &= ~IRQD_FORWARDED_TO_VCPU;
}

+static inline bool irqd_affinity_is_managed(struct irq_data *d)
+{
+ return __irqd_to_state(d) & IRQD_AFFINITY_MANAGED;
+}
+
#undef __irqd_to_state

static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d)
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index 09be2c9..b15aa3b 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -105,6 +105,8 @@ static inline void unregister_handler_proc(unsigned int irq,
struct irqaction *action) { }
#endif

+extern bool irq_can_set_affinity_usr(unsigned int irq);
+
extern int irq_select_affinity_usr(unsigned int irq, struct cpumask *mask);

extern void irq_set_thread_affinity(struct irq_desc *desc);
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index ef0bc02..30658e9 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -115,12 +115,12 @@ EXPORT_SYMBOL(synchronize_irq);
#ifdef CONFIG_SMP
cpumask_var_t irq_default_affinity;

-static int __irq_can_set_affinity(struct irq_desc *desc)
+static bool __irq_can_set_affinity(struct irq_desc *desc)
{
if (!desc || !irqd_can_balance(&desc->irq_data) ||
!desc->irq_data.chip || !desc->irq_data.chip->irq_set_affinity)
- return 0;
- return 1;
+ return false;
+ return true;
}

/**
@@ -134,6 +134,21 @@ int irq_can_set_affinity(unsigned int irq)
}

/**
+ * irq_can_set_affinity_usr - Check if affinity of a irq can be set from user space
+ * @irq: Interrupt to check
+ *
+ * Like irq_can_set_affinity() above, but additionally checks for the
+ * AFFINITY_MANAGED flag.
+ */
+bool irq_can_set_affinity_usr(unsigned int irq)
+{
+ struct irq_desc *desc = irq_to_desc(irq);
+
+ return __irq_can_set_affinity(desc) &&
+ !irqd_affinity_is_managed(&desc->irq_data);
+}
+
+/**
* irq_set_thread_affinity - Notify irq threads to adjust affinity
* @desc: irq descriptor which has affitnity changed
*
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index 4e1b947..40bdcdc 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -96,7 +96,7 @@ static ssize_t write_irq_affinity(int type, struct file *file,
cpumask_var_t new_value;
int err;

- if (!irq_can_set_affinity(irq) || no_irq_affinity)
+ if (!irq_can_set_affinity_usr(irq) || no_irq_affinity)
return -EIO;

if (!alloc_cpumask_var(&new_value, GFP_KERNEL))
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