[tip:sched/core] cpu/hotplug: Read_lock(tasklist_lock) doesn' t need to disable irqs

tip-bot for Oleg Nesterov
2015-09-13T10:58:55Z

Commit-ID: a75a6068dac25d4022ebcd82192ed6345407843c
Gitweb: http://git.kernel.org/tip/a75a6068dac25d4022ebcd82192ed6345407843c
Author: Oleg Nesterov <oleg@redhat.com>
AuthorDate: Thu, 10 Sep 2015 15:07:50 +0200
Committer: Ingo Molnar <mingo@kernel.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@redhat.com>
Reviewed-by: Kirill Tkhai <ktkhai@odin.com>
Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Kirill Tkhai <ktkhai@parallels.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20150910130750.GA20055@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.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 {