linux-kernel - Re: [PATCH 3/4] kernel: add support for TIF_NOTIFY

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Date:   Tue, 13 Oct 2020 17:45:57 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
        io-uring@...r.kernel.org
Cc:     peterz@...radead.org, oleg@...hat.com
Subject: Re: [PATCH 3/4] kernel: add support for TIF_NOTIFY_SIGNAL

On 10/13/20 5:42 PM, Thomas Gleixner wrote:
> On Thu, Oct 08 2020 at 09:27, Jens Axboe wrote:
>> This adds TIF_NOTIFY_SIGNAL handling in the generic code, which if set,
>> will return true if signal_pending() is used in a wait loop. That causes
>> an exit of the loop so that notify_signal tracehooks can be run. If the
>> wait loop is currently inside a system call, the system call is restarted
>> once task_work has been processed.
>>
>> x86 is using the generic entry code, add the necessary TIF_NOTIFY_SIGNAL
>> definitions for it.
> 
> Can you please split that into core changes and a patch which adds
> support for x86?

Sure, I'll split it into generic and then x86 after that.

>>  static inline int signal_pending(struct task_struct *p)
>>  {
>> +#ifdef TIF_NOTIFY_SIGNAL
> 
> As I said in the other thread, plase make this
> 
> #if defined(CONFIG_GENERIC_ENTRY) && defined(TIF_NOTIFY_SIGNAL)

Thanks, I'll make those tweaks.

> Other than that, this approach of using arch_do_signal() addresses my
> earlier concerns about the syscall restart machinery.

Great! Thanks for taking a look.

-- 
Jens Axboe