linux-kernel - Re: [PATCH V1] rtc: loongson: Add missing alarm notifications for ACPI RTC events

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <48586F8AA034EA7A+02ca49ef-db27-47a5-8de3-3407dcfb48a5@kylinsec.com.cn>
Date: Fri, 9 May 2025 16:06:07 +0800
From: Liu Dalin <liudalin@...insec.com.cn>
To: Binbin Zhou <zhoubinbin@...ngson.cn>, alexandre.belloni@...tlin.com,
 wangming01@...ngson.cn
Cc: chenhuacai@...nel.org, gaojuxin@...ngson.cn, git@...0n.name,
 jiaxun.yang@...goat.com, keguang.zhang@...il.com, lixuefeng@...ngson.cn,
 linux-rtc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V1] rtc: loongson: Add missing alarm notifications for
 ACPI RTC events



在 2025/5/9 15:12, Binbin Zhou 写道:
> Hi:
> 
> On 2025/5/9 09:40, Liu Dalin wrote:
>> When an application sets and enables an alarm on Loongson RTC devices,
>> the alarm notification fails to propagate to userspace because the
>> ACPI event handler omits calling rtc_update_irq().
>>
>> As a result, processes waiting via select() or poll() on RTC device
>> files fail to receive alarm notifications.
>>
>> Fixes: 1b733a9ebc3d ("rtc: Add rtc driver for the Loongson family chips")
>> Signed-off-by: Liu Dalin <liudalin@...insec.com.cn>
> Technically I don't think this is a compliant patch, firstly this patch 
> should be V2 and also you should add "Changlog" for describing the 
> differences from the previous patch.
> Anyway, it's good to me.

Ok! There is another problem, if regmap_write(priv->regmap,
TOY_MATCH0_REG, 0) move to the end of loongson_rtc_handler as 
09471d8f5b39("rtc: loongson: clear TOY_MATCH0_REG in 
loongson_rtc_isr()"), the interrupt also can be triggered multiple times.

So the regmap_write(priv->regmap,TOY_MATCH0_REG, 0) is move behind of 
rtc_update_irq by me, then the interrupt was triggered OK.

Is there any problem ?

> 
> Reviewed-by: Binbin Zhou <zhoubinbin@...ngson.cn>
> 
>> ---
>>   drivers/rtc/rtc-loongson.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/rtc/rtc-loongson.c b/drivers/rtc/rtc-loongson.c
>> index 97e5625c064c..2ca7ffd5d7a9 100644
>> --- a/drivers/rtc/rtc-loongson.c
>> +++ b/drivers/rtc/rtc-loongson.c
>> @@ -129,6 +129,14 @@ static u32 loongson_rtc_handler(void *id)
>>   {
>>       struct loongson_rtc_priv *priv = (struct loongson_rtc_priv *)id;
>> +    rtc_update_irq(priv->rtcdev, 1, RTC_AF | RTC_IRQF);
>> +
>> +    /*
>> +     * The TOY_MATCH0_REG should be cleared 0 here,
>> +     * otherwise the interrupt cannot be cleared.
>> +     */
>> +    regmap_write(priv->regmap, TOY_MATCH0_REG, 0);
>> +
>>       spin_lock(&priv->lock);
>>       /* Disable RTC alarm wakeup and interrupt */
>>       writel(readl(priv->pm_base + PM1_EN_REG) & ~RTC_EN,
> Thanks.
> Binbin
> 
> 
>