From mboxrd@z Thu Jan  1 00:00:00 1970
References: <20150827091217.GB20679@hermes.click-hack.org>
 <1440668375-9773-1-git-send-email-henning.schild@siemens.com>
From: Jan Kiszka <jan.kiszka@siemens.com>
Message-ID: <55DEDB4A.704@siemens.com>
Date: Thu, 27 Aug 2015 11:41:30 +0200
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Subject: Re: [Xenomai] [PATCHv2] x86/ipipe: reserve irq num we use for
 IRQ_MOVE_CLEANUP_VECTOR
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To: Henning Schild <henning.schild@siemens.com>, xenomai@xenomai.org

On 2015-08-27 11:39, Henning Schild wrote:
> vector_irq must not contain the same irq number for two different
> vectors because ipipe dispatches based on irq numbers.
> For the special case of IRQ_MOVE_CLEANUP_VECTOR, the ipipe patch
> inserts a new entry in vector_irq. To ensure the required uniqueness
> we have to make sure Linux will never make a vector point to irq number
> IRQ_MOVE_CLEANUP_VECTOR.
> 
> Before that patch ipipe did dispatch device interrupts that happened to
> receive number 32 (IRQ_MOVE_CLEANUP_VECTOR) to the cleanup function, the
> device effectively lost its interrupts. Up to 3.18 that was no problem
> since the allocator did not hand out the number ipipe failed to reserve.
> 
> Signed-off-by: Henning Schild <henning.schild@siemens.com>
> ---
>  arch/x86/kernel/irqinit.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
> index e850981..5ca517f 100644
> --- a/arch/x86/kernel/irqinit.c
> +++ b/arch/x86/kernel/irqinit.c
> @@ -126,6 +126,7 @@ static void __init smp_intr_init(void)
>  #ifdef CONFIG_SMP
>  #if defined(CONFIG_X86_64) || defined(CONFIG_X86_LOCAL_APIC)
>  	unsigned cpu;
> +	int ret;

__maybe_unused, or you'll get warnings when either IPIPE or BUG is disabled.

Jan

>  
>  	/*
>  	 * The reschedule interrupt is a CPU-to-CPU reschedule-helper
> @@ -143,9 +144,13 @@ static void __init smp_intr_init(void)
>  	/* Low priority IPI to cleanup after moving an irq */
>  	set_intr_gate(IRQ_MOVE_CLEANUP_VECTOR, irq_move_cleanup_interrupt);
>  	set_bit(IRQ_MOVE_CLEANUP_VECTOR, used_vectors);
> +#ifdef CONFIG_IPIPE
> +	ret = irq_alloc_descs(IRQ_MOVE_CLEANUP_VECTOR, 0, 1, 0);
> +	BUG_ON(IRQ_MOVE_CLEANUP_VECTOR != ret);
>  	for_each_possible_cpu(cpu)
>  		per_cpu(vector_irq, cpu)[IRQ_MOVE_CLEANUP_VECTOR] =
>  			IRQ_MOVE_CLEANUP_VECTOR;
> +#endif
>  
>  	/* IPI used for rebooting/stopping */
>  	alloc_intr_gate(REBOOT_VECTOR, reboot_interrupt);
> 

-- 
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