linux-kernel - Re: [PATCH] uprobes: Improve scalability by reducing the contention on siglock

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Message-ID: <51a756b7-3c2f-9aeb-1418-b38b74108ee6@huawei.com>
Date: Fri, 2 Aug 2024 09:38:04 +0800
From: "Liao, Chang" <liaochang1@...wei.com>
To: Oleg Nesterov <oleg@...hat.com>
CC: <mhiramat@...nel.org>, <peterz@...radead.org>, <mingo@...hat.com>,
	<acme@...nel.org>, <namhyung@...nel.org>, <mark.rutland@....com>,
	<alexander.shishkin@...ux.intel.com>, <jolsa@...nel.org>,
	<irogers@...gle.com>, <adrian.hunter@...el.com>, <kan.liang@...ux.intel.com>,
	<linux-kernel@...r.kernel.org>, <linux-trace-kernel@...r.kernel.org>,
	<linux-perf-users@...r.kernel.org>
Subject: Re: [PATCH] uprobes: Improve scalability by reducing the contention
 on siglock



在 2024/8/1 22:06, Oleg Nesterov 写道:
> On 08/01, Liao Chang wrote:
>>
>> @@ -2276,22 +2277,25 @@ static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
>>  	int err = 0;
>>  
>>  	uprobe = utask->active_uprobe;
>> -	if (utask->state == UTASK_SSTEP_ACK)
>> +	switch (utask->state) {
>> +	case UTASK_SSTEP_ACK:
>>  		err = arch_uprobe_post_xol(&uprobe->arch, regs);
>> -	else if (utask->state == UTASK_SSTEP_TRAPPED)
>> +		break;
>> +	case UTASK_SSTEP_TRAPPED:
>>  		arch_uprobe_abort_xol(&uprobe->arch, regs);
>> -	else
>> +		fallthrough;
>> +	case UTASK_SSTEP_DENY_SIGNAL:
>> +		set_tsk_thread_flag(current, TIF_SIGPENDING);
>> +		break;
>> +	default:
>>  		WARN_ON_ONCE(1);
>> +	}
> 
> Liao, at first glance this change looks "obviously wrong" to me.

Oleg. Did i overlook some thing obvious here?

> 
> But let me read this patch more carefully and reply on weekend,
> I am a bit busy right now.

Sure, thanks.

> 
> Thanks,
> 
> Oleg.
> 
> 

-- 
BR
Liao, Chang