Re: [PATCH] IRQ: normalize chip->irq_set_affinity return value on x86 and IA64

[Dimitri Sivanich <sivanich@sgi.com>]

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@huawei.com>
> ---
>  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?

> +	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?

>  
> -	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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