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From: Kirill Tkhai <tkhai@yandex.ru>
To: Oleg Nesterov <oleg@redhat.com>, Kirill Tkhai <ktkhai@odin.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
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References: <20150525162722.5171.15901.stgit@pro> <1432575941.6866.42.camel@odin.com> <20150526194613.GC6978@redhat.com>
Subject: Re: [PATCH RFC 09/13] exit: Use for_each_thread() in do_wait()
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Date: Wed, 27 May 2015 12:33:49 +0300
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26.05.2015, 22:47, "Oleg Nesterov" <oleg@redhat.com>:
> On 05/25, Kirill Tkhai wrote:
>> šRefactoring, no functionality change.
>
> Hmm. unless I missed something this change is wrong.
>
>> š--- a/kernel/exit.c
>> š+++ b/kernel/exit.c
>> š@@ -1538,8 +1538,7 @@ static long do_wait(struct wait_opts *wo)
>>
>> ššššššššššset_current_state(TASK_INTERRUPTIBLE);
>> ššššššššššread_lock(&tasklist_lock);
>> š- tsk = current;
>> š- do {
>> š+ for_each_thread(current, tsk) {
>> ššššššššššššššššššretval = do_wait_thread(wo, tsk);
>> ššššššššššššššššššif (retval)
>> ššššššššššššššššššššššššššgoto end;
>> š@@ -1550,7 +1549,7 @@ static long do_wait(struct wait_opts *wo)
>>
>> ššššššššššššššššššif (wo->wo_flags & __WNOTHREAD)
>> ššššššššššššššššššššššššššbreak;
>> š- } while_each_thread(current, tsk);
>> š+ }
>
> Please note the __WNOTHREAD check. This is the rare case when we
> actually want while_each_thread() (although it should die anyway).
>
> for_each_thread() always starts from ->group_leader, but we need
> to start from "current" first.

Sure, this must be like below. Thanks!
I won't resend the whole series with only this one patch changed to
do not bomb mail boxes. Waiting for the review.

diff --git a/kernel/exit.c b/kernel/exit.c
index a268093..e4963d3 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1538,8 +1538,10 @@ static long do_wait(struct wait_opts *wo)
 
 	set_current_state(TASK_INTERRUPTIBLE);
 	read_lock(&tasklist_lock);
-	tsk = current;
-	do {
+	for_each_thread(current, tsk) {
+		if (wo->wo_flags & __WNOTHREAD)
+			tsk = current;
+
 		retval = do_wait_thread(wo, tsk);
 		if (retval)
 			goto end;
@@ -1550,7 +1552,7 @@ static long do_wait(struct wait_opts *wo)
 
 		if (wo->wo_flags & __WNOTHREAD)
 			break;
-	} while_each_thread(current, tsk);
+	}
 	read_unlock(&tasklist_lock);
 
 notask: