linux-kernel - [tip:sched/core] cpu/hotplug: Read_lock(tasklist

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Message-ID: <tip-a75a6068dac25d4022ebcd82192ed6345407843c@git.kernel.org>
Date:	Sun, 13 Sep 2015 03:56:47 -0700
From:	tip-bot for Oleg Nesterov <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	peterz@...radead.org, ktkhai@...allels.com,
	srikar@...ux.vnet.ibm.com, ktkhai@...n.com, tglx@...utronix.de,
	mingo@...nel.org, oleg@...hat.com, hpa@...or.com,
	linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org
Subject: [tip:sched/core] cpu/hotplug: Read_lock(tasklist_lock) doesn'
 t need to disable irqs

Commit-ID:  a75a6068dac25d4022ebcd82192ed6345407843c
Gitweb:     http://git.kernel.org/tip/a75a6068dac25d4022ebcd82192ed6345407843c
Author:     Oleg Nesterov <oleg@...hat.com>
AuthorDate: Thu, 10 Sep 2015 15:07:50 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Sat, 12 Sep 2015 11:54:27 +0200

cpu/hotplug: Read_lock(tasklist_lock) doesn't need to disable irqs

check_for_tasks() doesn't need to disable irqs, recursive
read_lock() from interrupt is fine.

While at it, s/do_each_thread/for_each_process_thread/.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
Reviewed-by: Kirill Tkhai <ktkhai@...n.com>
Reviewed-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc: Kirill Tkhai <ktkhai@...allels.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/20150910130750.GA20055@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/cpu.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 82cf9df..050c634 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -304,8 +304,8 @@ static inline void check_for_tasks(int dead_cpu)
 {
 	struct task_struct *g, *p;
 
-	read_lock_irq(&tasklist_lock);
-	do_each_thread(g, p) {
+	read_lock(&tasklist_lock);
+	for_each_process_thread(g, p) {
 		if (!p->on_rq)
 			continue;
 		/*
@@ -320,8 +320,8 @@ static inline void check_for_tasks(int dead_cpu)
 
 		pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n",
 			p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags);
-	} while_each_thread(g, p);
-	read_unlock_irq(&tasklist_lock);
+	}
+	read_unlock(&tasklist_lock);
 }
 
 struct take_cpu_down_param {
--
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