Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Subject: Re: [PATCH v4 3/4] MIPS: Return earlier in die() if notify_die()
 returns NOTIFY_STOP
To:     Huacai Chen <chenhuacai@kernel.org>
References: <1692434183-2054-1-git-send-email-yangtiezhu@loongson.cn>
 <1692434183-2054-4-git-send-email-yangtiezhu@loongson.cn>
 <CAAhV-H5_3NeAEqiBgXqxwhUbTGRhEO0fL2bY4KCOJ6J=cf9Emw@mail.gmail.com>
Cc:     Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        "Maciej W. Rozycki" <macro@orcam.me.uk>,
        linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
        loongson-kernel@lists.loongnix.cn
From:   Tiezhu Yang <yangtiezhu@loongson.cn>
Message-ID: <467fb231-4b0a-478e-0f68-358d0651fc05@loongson.cn>
Date:   Mon, 21 Aug 2023 10:28:51 +0800
User-Agent: Mozilla/5.0 (X11; Linux mips64; rv:45.0) Gecko/20100101
 Thunderbird/45.4.0
MIME-Version: 1.0
In-Reply-To: <CAAhV-H5_3NeAEqiBgXqxwhUbTGRhEO0fL2bY4KCOJ6J=cf9Emw@mail.gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk


On 08/20/2023 04:53 PM, Huacai Chen wrote:
> Hi, Tiezhu,
>
> On Sun, Aug 20, 2023 at 7:21 AM Tiezhu Yang <yangtiezhu@loongson.cn> wrote:
>>
>> After the call to oops_exit(), it should not panic or execute
>> the crash kernel if the oops is to be suppressed.
>>
>> Suggested-by: Maciej W. Rozycki <macro@orcam.me.uk>
>> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
>> ---
>>  arch/mips/kernel/traps.c | 6 ++++--
>>  1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
>> index 8e528a8..fd770dc 100644
>> --- a/arch/mips/kernel/traps.c
>> +++ b/arch/mips/kernel/traps.c
>> @@ -412,6 +412,9 @@ void die(const char *str, struct pt_regs *regs)
>>
>>         oops_exit();
>>
>> +       if (ret == NOTIFY_STOP)
>> +               return;
>> +
>>         if (in_interrupt())
>>                 panic("Fatal exception in interrupt");
>>
>> @@ -421,8 +424,7 @@ void die(const char *str, struct pt_regs *regs)
>>         if (regs && kexec_should_crash(current))
>>                 crash_kexec(regs);
>>
>> -       if (ret != NOTIFY_STOP)
>> -               make_task_dead(SIGSEGV);
>> +       make_task_dead(SIGSEGV);
> Then you call make_task_dead() at the end unconditionally, and die()
> becomes a noreturn function again.

No, it can return if (ret == NOTIFY_STOP), so die() is a return
function now, please see objdump -d arch/mips/kernel/traps.o.

Thanks,
Tiezhu