RE: [PATCH] x86/irq,io_apic: Fix wrong unmask_ioapic calling whenthe irq is masked

[Liu, Chuansheng]

Hi Thomas and Ingo,

Could you have a look for this patch? It fix the wrong unmask action.
Thanks.

> -----Original Message-----
> From: Liu, Chuansheng
> Sent: Thursday, November 15, 2012 12:53 AM
> To: mingo@xxxxxxxxxx; tglx@xxxxxxxxxxxxx
> Cc: x86@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Liu, Chuansheng
> Subject: [PATCH] x86/irq,io_apic: Fix wrong unmask_ioapic calling when the irq
> is masked
> 
> 
> There is one typical case will cause this issue, that is:
> One io-apic interrupt with ONE_SHOT and threaded, when interrupt is coming:
> handle_fasteoi_irq()
> --> mask_irq(desc)
>     ...
>     desc->irq_data.chip->irq_eoi(&desc->irq_data)[ack_apic_level]
>     --> ioapic_irqd_mask()
>         ...
>         ioapic_irqd_unmask()
> 
> After that, the irq will be in unmasked state.
> 
> It will break the ONE_SHOT and threaded irq, and brings some unwanted
> issues.
> Here adding the irqd_irq_masked() condition to know if unmasking action is
> needed.
> 
> Signed-off-by: liu chuansheng <chuansheng.liu@xxxxxxxxx>
> ---
>  arch/x86/kernel/apic/io_apic.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
> index 1817fa9..d963e76 100644
> --- a/arch/x86/kernel/apic/io_apic.c
> +++ b/arch/x86/kernel/apic/io_apic.c
> @@ -2479,7 +2479,8 @@ static inline void ioapic_irqd_unmask(struct irq_data
> *data,
>  		 */
>  		if (!io_apic_level_ack_pending(cfg))
>  			irq_move_masked_irq(data);
> -		unmask_ioapic(cfg);
> +		if (!irqd_irq_masked(data))
> +			unmask_ioapic(cfg);
>  	}
>  }
>  #else
> --
> 1.7.0.4
> 
> 

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