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From: Maninder Singh <maninder1.s@samsung.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
	"mhocko@suse.cz" <mhocko@suse.cz>,
	"peterz@infradead.org" <peterz@infradead.org>,
	"mingo@kernel.org" <mingo@kernel.org>,
	"riel@redhat.com" <riel@redhat.com>,
	"ionut.m.alexa@gmail.com" <ionut.m.alexa@gmail.com>,
	"peter@hurleysoftware.com" <peter@hurleysoftware.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [EDT][PATCH] kernel/exit.c : Fix missing read_unlock
Date: Fri, 22 May 2015 03:36:51 +0000 (GMT)	[thread overview]
Message-ID: <698657669.25971432265807247.JavaMail.weblogic@epmlwas06d> (raw)

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 EP-F6AA0618C49C4AEDA73BFF1B39950BAB

Hi Oleg,

>> Hi,
>>
>> From: Maninder Singh <maninder1.s@samsung.com>
>>
>> Subject: [PATCH 1/1] kernel/exit.c : Fix missing task_unlock
>>
>> This patch adds missing read_unlock if do_wait_thread or ptrace_do_wait
>> returns non zero.
>
>Confused...
>
>wait_consider_task() should drop tasklist_lock if it returns non-zero?
>
>
>> --- a/kernel/exit.c
>> +++ b/kernel/exit.c
>> @@ -1486,12 +1486,16 @@ repeat:
>>  	tsk = current;
>>  	do {
>>  		retval = do_wait_thread(wo, tsk);
>> -		if (retval)
>> +		if (retval) {
>> +			read_unlock(&tasklist_lock);
>>  			goto end;
>> +		}
>>
>>  		retval = ptrace_do_wait(wo, tsk);
>> -		if (retval)
>> +		if (retval) {
>> +			read_unlock(&tasklist_lock);
>>  			goto end;
>> +		}
>
>Well, the patch is obviously wrong. Because, again, tasklist_lock was
>already unlocked if (say) wait_task_zombie() reaps a child.

Yes, agree, My wrong
>If you think there is a case which forgets to unlock, please tell us
>more.
I have checked It is getting unlocked in wait_task_zombie Sorry for unnecessary disturbance. 

>Oleg.
Thanks

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             reply	other threads:[~2015-05-22  3:36 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-05-22  3:36 Maninder Singh [this message]
  -- strict thread matches above, loose matches on Subject: below --
2015-05-21 11:44 [EDT][PATCH] kernel/exit.c : Fix missing read_unlock Maninder Singh
2015-05-21  6:34 Maninder Singh
2015-05-21 10:58 ` Ingo Molnar
2015-05-21  5:00 Maninder Singh
2015-05-21  6:03 ` Ingo Molnar
2015-05-21 10:32   ` Frans Klaver
2015-05-21 10:56     ` Ingo Molnar
2015-05-21 11:39       ` Frans Klaver
2015-05-21 18:16 ` Oleg Nesterov

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