linux-kernel - Re: [PATCH 06/12] genericirq: make irq

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Date:	Thu, 04 Mar 2010 10:56:16 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Thomas Gleixner <tglx@...utronix.de>
CC:	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Suresh Siddha <suresh.b.siddha@...el.com>,
	Eric Biederman <ebiederm@...ssion.com>,
	LKML <linux-kernel@...r.kernel.org>, Julia Lawall <julia@...u.dk>
Subject: Re: [PATCH 06/12] genericirq: make irq_chip related function to take
 desc

On 03/04/2010 06:31 AM, Thomas Gleixner wrote:
> On Thu, 4 Mar 2010, Yinghai Lu wrote:
> 
>>  /*
>>   * Fixup enable/disable function pointers
>>   */
>>  void irq_chip_set_defaults(struct irq_chip *chip)
>>  {
>> +	if (!chip->desc_enable)
>> +		chip->desc_enable = default_enable_desc;
>> +	if (!chip->desc_disable)
>> +		chip->desc_disable = default_disable_desc;
>> +	if (!chip->desc_startup)
>> +		chip->desc_startup = default_startup_desc;
> 
>   This will break all irq_chips which implement enable, disable or
>   startup. so the check needs to be:
> 
>   	   if (!chip->enable && !chip->desc_enable) 
yes.
> 
>> +	/*
>> +	 * We use chip->disable, when the user provided its own. When
>> +	 * we have default_disable set for chip->disable, then we need
>> +	 * to use default_shutdown, otherwise the irq line is not
>> +	 * disabled on free_irq():
>> +	 */
>> +	if (!chip->desc_shutdown)
>> +		chip->desc_shutdown = chip->desc_disable != default_disable_desc ?
>> +			chip->desc_disable : default_shutdown_desc;
>> +	if (!chip->desc_end)
>> +		chip->desc_end = dummy_irq_chip.desc_end;
> 
>   Same  here.
> 
>> @@ -295,10 +295,14 @@ void clear_kstat_irqs(struct irq_desc *desc)
>>  static void ack_bad(unsigned int irq)
> 
>   Why do we keep that function around ?

that is for other arch...

/*
 * Generic no controller implementation
 */
struct irq_chip no_irq_chip = {
        .name           = "none",
        .startup        = noop_ret,
        .shutdown       = noop,
        .enable         = noop,
        .disable        = noop,
        .ack            = ack_bad,
        .end            = noop,

        .desc_startup   = noop_ret_desc,
        .desc_shutdown  = noop_desc,
        .desc_enable    = noop_desc,
        .desc_disable   = noop_desc,
        .desc_ack       = ack_bad_desc,
        .desc_end       = noop_desc,
};


> 
>>  {
>>  	struct irq_desc *desc = irq_to_desc(irq);
>> -
>> -	print_irq_desc(irq, desc);
>> +	print_irq_desc(desc);
>>  	ack_bad_irq(irq);
>>  }
> 
>   
>>  /*
>>   * Generic no controller implementation
>> @@ -323,6 +334,13 @@ struct irq_chip no_irq_chip = {
>>  	.disable	= noop,
>>  	.ack		= ack_bad,
>>  	.end		= noop,
> 
>   We can remove the old ones right away, can't we ?
> 
>> diff --git a/kernel/irq/resend.c b/kernel/irq/resend.c
> 
> Yinghai, thanks for doing that. It's halfways reviewable now, but if
> we go that way it needs to be split further, really.
> 
> But to be honest I have to say that the code churn of that patch
> scares me. I expected it to be less horrible.
> 
> So I started twisting my brain around a fully automated method of
> solving this conversion problem with almost zero risk. It just occured
> to me that Julia might be able to help and whip up semantic patch
> rules for doing the conversion automagically on a flag day. That would
> be one rule and one resulting patch for each of the chip->functions.
> 
> So the task would be:
> 
> In include/linux/irq.h
> 
>   struct irq_chip {
>         const char      *name;
> - 	unsigned int    startup(unsigned int irq);
> + 	unsigned int    startup(struct irq_desc *desc);
> 
> Then finding all irq_chip implementations which set that function
> pointer and fix up the function e.g.:
> 
> arch/x86/kernel/apic/io_apic.c: 
> 
> static struct irq_chip ioapic_chip __read_mostly = {
>         .name           = "IO-APIC",
>         .startup        = startup_ioapic_irq,
> 
> -->
> 
> -static unsigned int startup_ioapic_irq(unsigned int irq)
> +static unsigned int startup_ioapic_irq(struct irq_desc *desc)
>  {
> +	unsigned int irq = desc->irq;
>         int was_pending = 0;
>         unsigned long flags;
>         struct irq_cfg *cfg;
> 
>         raw_spin_lock_irqsave(&ioapic_lock, flags);
> ...
> 
> To make it simple, we just can put that right after the opening
> bracket of the function.
> 
> The code which uses the chip functions needs to be changed:
> 
> -	desc->chip->fun(irq);
> +	desc->chip->fun(desc);
> 
> That's mostly in kernel/irq/* but there are some users in arch/*
> lowlevel irq handling code as well.

that is our -v2 version.

YH

View attachment "x86_irq_chip_x999999.patch" of type "text/x-patch" (557249 bytes)