linux-kernel - Re: [RESEND PATCH v2 28/33] ARM: davinci: cp-intc: unify error handling

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Date:   Mon, 11 Feb 2019 13:20:20 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     Bartosz Golaszewski <bgolaszewski@...libre.com>
Cc:     Bartosz Golaszewski <brgl@...ev.pl>, Sekhar Nori <nsekhar@...com>,
        Kevin Hilman <khilman@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        David Lechner <david@...hnology.com>,
        arm-soc <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH v2 28/33] ARM: davinci: cp-intc: unify error
 handling

On 11/02/2019 13:10, Bartosz Golaszewski wrote:
> pon., 11 lut 2019 o 14:08 Marc Zyngier <marc.zyngier@....com> napisał(a):
>>
>> On 11/02/2019 12:26, Bartosz Golaszewski wrote:
>>> From: Bartosz Golaszewski <bgolaszewski@...libre.com>
>>>
>>> Use WARN_ON() on eny error in cp-intc initialization and drop all
>>> custom error messages.
>>>
>>> Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
>>> Reviewed-by: David Lechner <david@...hnology.com>
>>> ---
>>>  arch/arm/mach-davinci/cp_intc.c | 10 +++-------
>>>  1 file changed, 3 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/arch/arm/mach-davinci/cp_intc.c b/arch/arm/mach-davinci/cp_intc.c
>>> index f3787ae4cdbd..c1efb9390655 100644
>>> --- a/arch/arm/mach-davinci/cp_intc.c
>>> +++ b/arch/arm/mach-davinci/cp_intc.c
>>> @@ -200,20 +200,16 @@ davinci_cp_intc_do_init(const struct davinci_cp_intc_config *config,
>>>                       DAVINCI_CP_INTC_CHAN_MAP(offset));
>>>
>>>       irq_base = irq_alloc_descs(-1, 0, config->num_irqs, 0);
>>> -     if (irq_base < 0) {
>>> -             pr_warn("Couldn't allocate IRQ numbers\n");
>>> -             irq_base = 0;
>>> -     }
>>> +     if (WARN_ON(irq_base < 0))
>>> +             return irq_base;
>>>
>>>       /* create a legacy host */
>>>       davinci_cp_intc_irq_domain = irq_domain_add_legacy(
>>>                                       node, config->num_irqs, irq_base, 0,
>>>                                       &davinci_cp_intc_irq_domain_ops, NULL);
>>>
>>> -     if (!davinci_cp_intc_irq_domain) {
>>> -             pr_err("cp_intc: failed to allocate irq host!\n");
>>> +     if (WARN_ON(!davinci_cp_intc_irq_domain))
>>>               return -EINVAL;
>>> -     }
>>>
>>>       set_handle_irq(davinci_cp_intc_handle_irq);
>>>
>>>
>>
>> I'm sorry, but how is turning an explicit message into a long stack
>> trace really useful?
>>
> 
> If any of these calls fails, the system is fried. I assumed that a
> stack trace will point users straight to the offending line.

The message is a really good clue, because you can actually grep for it,
and it gives you the exact symptom. You are actively removing
information here.

	M.
-- 
Jazz is not dead. It just smells funny...