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Subject[PATCH] [genirq] Expose default irq affinity mask
Date
Current IRQ affinity interface does not provide a way to set affinity
for the IRQs that will be allocated/activated in the future.
This patch creates /proc/irq/default_smp_affinity that lets users set
default affinity mask for the newly allocated IRQs. Changing default
does not affect affinity masks for the currently active IRQs, they
have to be changed explicitly.

Signed-off-by: Max Krasnyansky <maxk@qualcomm.com>
---
arch/alpha/kernel/irq.c | 5 +--
include/linux/irq.h | 14 ++++-------
kernel/irq/manage.c | 28 +++++++++++++++++++++-
kernel/irq/proc.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++-
4 files changed, 89 insertions(+), 15 deletions(-)
diff --git a/arch/alpha/kernel/irq.c b/arch/alpha/kernel/irq.c
index facf82a..c626a82 100644
--- a/arch/alpha/kernel/irq.c
+++ b/arch/alpha/kernel/irq.c
@@ -42,8 +42,7 @@ void ack_bad_irq(unsigned int irq)
#ifdef CONFIG_SMP
static char irq_user_affinity[NR_IRQS];

-int
-select_smp_affinity(unsigned int irq)
+int irq_select_affinity(unsigned int irq)
{
static int last_cpu;
int cpu = last_cpu + 1;
@@ -51,7 +50,7 @@ select_smp_affinity(unsigned int irq)
if (!irq_desc[irq].chip->set_affinity || irq_user_affinity[irq])
return 1;

- while (!cpu_possible(cpu))
+ while (!cpu_possible(cpu) || !cpu_isset(cpu, irq_default_affinity))
cpu = (cpu < (NR_CPUS-1) ? cpu + 1 : 0);
last_cpu = cpu;

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 176e5e7..8faebf8 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -228,8 +228,11 @@ static inline void set_pending_irq(unsigned int irq, cpumask_t mask)

#endif /* CONFIG_GENERIC_PENDING_IRQ */

+extern cpumask_t irq_default_affinity;
+
extern int irq_set_affinity(unsigned int irq, cpumask_t cpumask);
extern int irq_can_set_affinity(unsigned int irq);
+extern int irq_select_affinity(unsigned int irq);

#else /* CONFIG_SMP */

@@ -243,6 +246,8 @@ static inline int irq_set_affinity(unsigned int irq, cpumask_t cpumask)

static inline int irq_can_set_affinity(unsigned int irq) { return 0; }

+static inline int irq_select_affinity(unsigned int irq) { return 0; }
+
#endif /* CONFIG_SMP */

#ifdef CONFIG_IRQBALANCE
@@ -253,15 +258,6 @@ static inline void set_balance_irq_affinity(unsigned int irq, cpumask_t mask)
}
#endif

-#ifdef CONFIG_AUTO_IRQ_AFFINITY
-extern int select_smp_affinity(unsigned int irq);
-#else
-static inline int select_smp_affinity(unsigned int irq)
-{
- return 1;
-}
-#endif
-
extern int no_irq_affinity;

static inline int irq_balancing_disabled(unsigned int irq)
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 438a014..90f9ccc 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -16,6 +16,8 @@

#ifdef CONFIG_SMP

+cpumask_t irq_default_affinity = CPU_MASK_ALL;
+
/**
* synchronize_irq - wait for pending IRQ handlers (on other CPUs)
* @irq: interrupt number to wait for
@@ -94,6 +96,27 @@ int irq_set_affinity(unsigned int irq, cpumask_t cpumask)
return 0;
}

+#ifndef CONFIG_AUTO_IRQ_AFFINITY
+/**
+ * Generic version of the affinity autoselector.
+ */
+int irq_select_affinity(unsigned int irq)
+{
+ cpumask_t mask;
+
+ if (!irq_can_set_affinity(irq))
+ return 0;
+
+ cpus_and(mask, cpu_online_map, irq_default_affinity);
+
+ irq_desc[irq].affinity = mask;
+ irq_desc[irq].chip->set_affinity(irq, mask);
+
+ set_balance_irq_affinity(irq, mask);
+ return 0;
+}
+#endif
+
#endif

/**
@@ -376,6 +399,9 @@ int setup_irq(unsigned int irq, struct irqaction *new)
} else
/* Undo nested disables: */
desc->depth = 1;
+
+ /* Set default affinity mask once everything is setup */
+ irq_select_affinity(irq);
}
/* Reset broken irq detection when installing new handler */
desc->irq_count = 0;
@@ -555,8 +581,6 @@ int request_irq(unsigned int irq, irq_handler_t handler,
action->next = NULL;
action->dev_id = dev_id;

- select_smp_affinity(irq);
-
#ifdef CONFIG_DEBUG_SHIRQ
if (irqflags & IRQF_SHARED) {
/*
diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c
index c2f2ccb..c20eb52 100644
--- a/kernel/irq/proc.c
+++ b/kernel/irq/proc.c
@@ -66,13 +66,51 @@ static int irq_affinity_write_proc(struct file *file, const char __user *buffer,
if (cpus_empty(tmp))
/* Special case for empty set - allow the architecture
code to set default SMP affinity. */
- return select_smp_affinity(irq) ? -EINVAL : full_count;
+ return irq_select_affinity(irq) ? -EINVAL : full_count;

irq_set_affinity(irq, new_value);

return full_count;
}

+extern cpumask_t irq_default_affinity;
+
+static int default_affinity_read(char *page, char **start, off_t off,
+ int count, int *eof, void *data)
+{
+ int len = cpumask_scnprintf(page, count, irq_default_affinity);
+ if (count - len < 2)
+ return -EINVAL;
+ len += sprintf(page + len, "\n");
+ return len;
+}
+
+static int default_affinity_write(struct file *file, const char __user *buffer,
+ unsigned long count, void *data)
+{
+ unsigned int full_count = count, err;
+ cpumask_t new_value, tmp;
+
+ err = cpumask_parse_user(buffer, count, new_value);
+ if (err)
+ return err;
+
+ if (!is_affinity_mask_valid(new_value))
+ return -EINVAL;
+
+ /*
+ * Do not allow disabling IRQs completely - it's a too easy
+ * way to make the system unusable accidentally :-) At least
+ * one online CPU still has to be targeted.
+ */
+ cpus_and(tmp, new_value, cpu_online_map);
+ if (cpus_empty(tmp))
+ return -EINVAL;
+
+ irq_default_affinity = new_value;
+
+ return full_count;
+}
#endif

static int irq_spurious_read(char *page, char **start, off_t off,
@@ -171,6 +209,21 @@ void unregister_handler_proc(unsigned int irq, struct irqaction *action)
remove_proc_entry(action->dir->name, irq_desc[irq].dir);
}

+void register_default_affinity_proc(void)
+{
+#ifdef CONFIG_SMP
+ struct proc_dir_entry *entry;
+
+ /* create /proc/irq/default_smp_affinity */
+ entry = create_proc_entry("default_smp_affinity", 0600, root_irq_dir);
+ if (entry) {
+ entry->data = NULL;
+ entry->read_proc = default_affinity_read;
+ entry->write_proc = default_affinity_write;
+ }
+#endif
+}
+
void init_irq_proc(void)
{
int i;
@@ -180,6 +233,8 @@ void init_irq_proc(void)
if (!root_irq_dir)
return;

+ register_default_affinity_proc();
+
/*
* Create entries for all existing IRQs.
*/
--
1.5.4.5


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