Re: [PATCH] IRQ: normalize chip->irq_set_affinity return value on x86and IA64

From: Jiang Liu
Date: Thu Mar 08 2012 - 19:57:22 EST

Hi Dimitri,
Thanks for review and please refer to the inline comments below.
On 2012-3-8 22:49, Dimitri Sivanich wrote:
On Tue, Mar 06, 2012 at 11:01:52PM +0800, Jiang Liu wrote:
On x86 and IA64 platforms, interrupt controller chip's irq_set_affinity()
method always copies affinity mask to irq_data->affinity field but still
returns 0(IRQ_SET_MASK_OK). That return value causes the interrupt core
logic unnecessarily copies the mask to irq_data->affinity field again.
So return IRQ_SET_MASK_OK_NOCOPY instead of IRQ_SET_MASK_OK to get rid of
the duplicated copy operation.

This patch applies to v3.3-rc6 and has been tested on x86 platforms.

Signed-off-by: Jiang Liu<jiang.liu@xxxxxxxxxx>
---
arch/ia64/kernel/iosapic.c | 4 +++-
arch/ia64/kernel/msi_ia64.c | 4 ++--
arch/ia64/sn/kernel/irq.c | 2 +-
arch/ia64/sn/kernel/msi_sn.c | 2 +-
arch/x86/kernel/apic/io_apic.c | 11 ++++++-----
arch/x86/platform/uv/uv_irq.c | 2 +-
kernel/irq/internals.h | 3 +++
kernel/irq/manage.c | 39 ++++++++++++++++++++++-----------------
kernel/irq/migration.c | 6 +-----
9 files changed, 40 insertions(+), 33 deletions(-)

diff --git a/arch/ia64/kernel/iosapic.c b/arch/ia64/kernel/iosapic.c
index b0f9afe..98f5fa6 100644
--- a/arch/ia64/kernel/iosapic.c
+++ b/arch/ia64/kernel/iosapic.c
@@ -374,8 +374,10 @@ iosapic_set_affinity(struct irq_data *data, const struct cpumask *mask,
iosapic_write(iosapic, IOSAPIC_RTE_LOW(rte_index), low32);
}


Maybe I haven't looked thoroughly enough, but could you point out where
the mask is being copied in this function?
The affinity mask is set through
iosapic_set_affinity()->
set_irq_affinity_info ()
{
if (irq < NR_IRQS) {
cpumask_copy(irq_get_irq_data(irq)->affinity,
cpumask_of(cpu_logical_id(hwid)));
irq_redir[irq] = (char) (redir & 0xff);
}
}


+ return IRQ_SET_MASK_OK_NOCOPY;
+#else
+ return IRQ_SET_MASK_OK;
#endif
- return 0;
}

/*
diff --git a/arch/ia64/kernel/msi_ia64.c b/arch/ia64/kernel/msi_ia64.c
index 94e0db7..e155770 100644
--- a/arch/ia64/kernel/msi_ia64.c
+++ b/arch/ia64/kernel/msi_ia64.c
@@ -41,7 +41,7 @@ static int ia64_set_msi_irq_affinity(struct irq_data *idata,
write_msi_msg(irq,&msg);
cpumask_copy(idata->affinity, cpumask_of(cpu));

- return 0;
+ return IRQ_SET_MASK_OK_NOCOPY;
}
#endif /* CONFIG_SMP */

@@ -157,7 +157,7 @@ static int dmar_msi_set_affinity(struct irq_data *data,
dmar_msi_write(irq,&msg);
cpumask_copy(data->affinity, mask);

- return 0;
+ return IRQ_SET_MASK_OK_NOCOPY;
}
#endif /* CONFIG_SMP */

diff --git a/arch/ia64/sn/kernel/irq.c b/arch/ia64/sn/kernel/irq.c
index dfac09a..f444208 100644
--- a/arch/ia64/sn/kernel/irq.c
+++ b/arch/ia64/sn/kernel/irq.c
@@ -216,7 +216,7 @@ static int sn_set_affinity_irq(struct irq_data *data,
sn_irq_lh[irq], list)
(void)sn_retarget_vector(sn_irq_info, nasid, slice);

Again, could you point out where the mask is being copied in this function?
This is through
sn_set_affinity_irq()->sn_retarget_vector()->set_irq_affinity_info()



- return 0;
+ return IRQ_SET_MASK_OK_NOCOPY;
}

#ifdef CONFIG_SMP
diff --git a/arch/ia64/sn/kernel/msi_sn.c b/arch/ia64/sn/kernel/msi_sn.c
index 2b98b9e..ebb5b55 100644
--- a/arch/ia64/sn/kernel/msi_sn.c
+++ b/arch/ia64/sn/kernel/msi_sn.c
@@ -208,7 +208,7 @@ static int sn_set_msi_irq_affinity(struct irq_data *data,
write_msi_msg(irq,&msg);
cpumask_copy(data->affinity, cpu_mask);

- return 0;
+ return IRQ_SET_MASK_OK_NOCOPY;
}
#endif /* CONFIG_SMP */

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index fb07275..a81f888 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2346,6 +2346,7 @@ ioapic_set_affinity(struct irq_data *data, const struct cpumask *mask,
/* Only the high 8 bits are valid. */
dest = SET_APIC_LOGICAL_ID(dest);
__target_IO_APIC_irq(irq, dest, data->chip_data);
+ ret = IRQ_SET_MASK_OK_NOCOPY;
}
raw_spin_unlock_irqrestore(&ioapic_lock, flags);
return ret;
@@ -2404,7 +2405,7 @@ ir_ioapic_set_affinity(struct irq_data *data, const struct cpumask *mask,
send_cleanup_vector(cfg);

cpumask_copy(data->affinity, mask);
- return 0;
+ return IRQ_SET_MASK_OK_NOCOPY;
}

#else
@@ -3209,7 +3210,7 @@ msi_set_affinity(struct irq_data *data, const struct cpumask *mask, bool force)

__write_msi_msg(data->msi_desc,&msg);

- return 0;
+ return IRQ_SET_MASK_OK_NOCOPY;
}
#endif /* CONFIG_SMP */

@@ -3366,7 +3367,7 @@ dmar_msi_set_affinity(struct irq_data *data, const struct cpumask *mask,

dmar_msi_write(irq,&msg);

- return 0;
+ return IRQ_SET_MASK_OK_NOCOPY;
}

#endif /* CONFIG_SMP */
@@ -3419,7 +3420,7 @@ static int hpet_msi_set_affinity(struct irq_data *data,

hpet_msi_write(data->handler_data,&msg);

- return 0;
+ return IRQ_SET_MASK_OK_NOCOPY;
}

#endif /* CONFIG_SMP */
@@ -3499,7 +3500,7 @@ ht_set_affinity(struct irq_data *data, const struct cpumask *mask, bool force)
return -1;

target_ht_irq(data->irq, dest, cfg->vector);
- return 0;
+ return IRQ_SET_MASK_OK_NOCOPY;
}

#endif
diff --git a/arch/x86/platform/uv/uv_irq.c b/arch/x86/platform/uv/uv_irq.c
index f25c276..a22c416 100644
--- a/arch/x86/platform/uv/uv_irq.c
+++ b/arch/x86/platform/uv/uv_irq.c
@@ -222,7 +222,7 @@ uv_set_irq_affinity(struct irq_data *data, const struct cpumask *mask,
if (cfg->move_in_progress)
send_cleanup_vector(cfg);

- return 0;
+ return IRQ_SET_MASK_OK_NOCOPY;
}

/*
diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h
index b795231..2c49c40 100644
--- a/kernel/irq/internals.h
+++ b/kernel/irq/internals.h
@@ -103,6 +103,9 @@ extern int irq_select_affinity_usr(unsigned int irq, struct cpumask *mask);

extern void irq_set_thread_affinity(struct irq_desc *desc);

+extern int irq_do_set_affinity(struct irq_data *data,
+ const struct cpumask *dest, bool force);
+
/* Inline functions for support of irq chips on slow busses */
static inline void chip_bus_lock(struct irq_desc *desc)
{
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index a9a9dbe..b410b0b 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -139,6 +139,25 @@ static inline void
irq_get_pending(struct cpumask *mask, struct irq_desc *desc) { }
#endif

+int irq_do_set_affinity(struct irq_data *data, const struct cpumask *mask,
+ bool force)
+{
+ struct irq_desc *desc = irq_data_to_desc(data);
+ struct irq_chip *chip = irq_data_get_irq_chip(data);
+ int ret;
+
+ ret = chip->irq_set_affinity(data, mask, false);
+ switch (ret) {
+ case IRQ_SET_MASK_OK:
+ cpumask_copy(data->affinity, mask);
+ case IRQ_SET_MASK_OK_NOCOPY:
+ irq_set_thread_affinity(desc);
+ ret = 0;
+ }
+
+ return ret;
+}
+
int __irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask)
{
struct irq_chip *chip = irq_data_get_irq_chip(data);
@@ -149,14 +168,7 @@ int __irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask)
return -EINVAL;

if (irq_can_move_pcntxt(data)) {
- ret = chip->irq_set_affinity(data, mask, false);
- switch (ret) {
- case IRQ_SET_MASK_OK:
- cpumask_copy(data->affinity, mask);
- case IRQ_SET_MASK_OK_NOCOPY:
- irq_set_thread_affinity(desc);
- ret = 0;
- }
+ ret = irq_do_set_affinity(data, mask, false);
} else {
irqd_set_move_pending(data);
irq_copy_pending(desc, mask);
@@ -280,9 +292,7 @@ EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
static int
setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
{
- struct irq_chip *chip = irq_desc_get_chip(desc);
struct cpumask *set = irq_default_affinity;
- int ret;

/* Excludes PER_CPU and NO_BALANCE interrupts */
if (!irq_can_set_affinity(irq))
@@ -301,13 +311,8 @@ setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
}

cpumask_and(mask, cpu_online_mask, set);
- ret = chip->irq_set_affinity(&desc->irq_data, mask, false);
- switch (ret) {
- case IRQ_SET_MASK_OK:
- cpumask_copy(desc->irq_data.affinity, mask);
- case IRQ_SET_MASK_OK_NOCOPY:
- irq_set_thread_affinity(desc);
- }
+ irq_do_set_affinity(&desc->irq_data, mask, false);
+
return 0;
}
#else
diff --git a/kernel/irq/migration.c b/kernel/irq/migration.c
index 4742090..ef04dab 100644
--- a/kernel/irq/migration.c
+++ b/kernel/irq/migration.c
@@ -44,11 +44,7 @@ void irq_move_masked_irq(struct irq_data *idata)
*/
if (likely(cpumask_any_and(desc->pending_mask, cpu_online_mask)
< nr_cpu_ids))
- if (!chip->irq_set_affinity(&desc->irq_data,
- desc->pending_mask, false)) {
- cpumask_copy(desc->irq_data.affinity, desc->pending_mask);
- irq_set_thread_affinity(desc);
- }
+ irq_do_set_affinity(&desc->irq_data, desc->pending_mask, false);

cpumask_clear(desc->pending_mask);
}
--
1.7.5.4

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