linux-kernel - Re: [PATCH v16 05/15] clocksource/drivers/arm_arch_timer: fix a bug in arch_timer_register about arch_timer_uses

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Date:   Mon, 21 Nov 2016 15:32:21 +0800
From:   Fu Wei <fu.wei@...aro.org>
To:     Mark Rutland <mark.rutland@....com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <marc.zyngier@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        Hanjun Guo <hanjun.guo@...aro.org>,
        linux-arm-kernel@...ts.infradead.org,
        Linaro ACPI Mailman List <linaro-acpi@...ts.linaro.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        rruigrok@...eaurora.org, "Abdulhamid, Harb" <harba@...eaurora.org>,
        Christopher Covington <cov@...eaurora.org>,
        Timur Tabi <timur@...eaurora.org>,
        G Gregory <graeme.gregory@...aro.org>,
        Al Stone <al.stone@...aro.org>, Jon Masters <jcm@...hat.com>,
        Wei Huang <wei@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
        Leo Duran <leo.duran@....com>,
        Wim Van Sebroeck <wim@...ana.be>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-watchdog@...r.kernel.org, Tomasz Nowicki <tn@...ihalf.com>,
        Christoffer Dall <christoffer.dall@...aro.org>,
        Julien Grall <julien.grall@....com>
Subject: Re: [PATCH v16 05/15] clocksource/drivers/arm_arch_timer: fix a bug
 in arch_timer_register about arch_timer_uses_ppi

Hi Mark,

On 19 November 2016 at 02:52, Mark Rutland <mark.rutland@....com> wrote:
> On Wed, Nov 16, 2016 at 09:48:58PM +0800, fu.wei@...aro.org wrote:
>> From: Fu Wei <fu.wei@...aro.org>
>>
>> The patch fix a potential bug about arch_timer_uses_ppi in
>> arch_timer_register.
>> On ARM64, we don't use ARCH_TIMER_PHYS_SECURE_PPI in Linux, so we will
>> just igorne it in init code.
>
> That's not currently the case. I assume you mean we will in later
> patches? If so, please make that clear in the commit message.
>
>> If arch_timer_uses_ppi is ARCH_TIMER_PHYS_NONSECURE_PPI, the orignal
>> code of arch_timer_uses_ppi may go wrong.
>
> How? What specifically happens?
>
> We don't currently assign ARCH_TIMER_PHYS_NONSECURE_PPI to
> arch_timer_uses_ppi, so I assume a later patch changes this. This change
> should be folded into said patch; it doesn't make sense in isolation.

yes, this patch is a preparation for the next which may set
arch_timer_use_ppi as ARCH_TIMER_PHYS_NONSECURE_PPI.
So you are right, I will merge this into the next and mention this
change in the commit message.

Great thanks

>
> Thanks,
> Mark.
>
>> Signed-off-by: Fu Wei <fu.wei@...aro.org>
>> ---
>>  drivers/clocksource/arm_arch_timer.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
>> index dd1040d..6de164f 100644
>> --- a/drivers/clocksource/arm_arch_timer.c
>> +++ b/drivers/clocksource/arm_arch_timer.c
>> @@ -699,7 +699,7 @@ static int __init arch_timer_register(void)
>>       case ARCH_TIMER_PHYS_NONSECURE_PPI:
>>               err = request_percpu_irq(ppi, arch_timer_handler_phys,
>>                                        "arch_timer", arch_timer_evt);
>> -             if (!err && arch_timer_ppi[ARCH_TIMER_PHYS_NONSECURE_PPI]) {
>> +             if (!err && arch_timer_has_nonsecure_ppi()) {
>>                       ppi = arch_timer_ppi[ARCH_TIMER_PHYS_NONSECURE_PPI];
>>                       err = request_percpu_irq(ppi, arch_timer_handler_phys,
>>                                                "arch_timer", arch_timer_evt);
>> --
>> 2.7.4
>>



-- 
Best regards,

Fu Wei
Software Engineer
Red Hat