* [PATCH 0/2] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop()
@ 2015-07-08 19:41 Oleg Nesterov
2015-07-08 19:42 ` [PATCH 1/2] " Oleg Nesterov
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: Oleg Nesterov @ 2015-07-08 19:41 UTC (permalink / raw)
To: Alexei Starovoitov, David S. Miller, Eric Dumazet
Cc: Jan Stancek, Marcelo Leitner, netdev, linux-kernel
Hello,
I am not familiar with this code and I have no idea how to test
these changes, so 2/2 comes as a separate change. 1/2 looks like
the obvious bugfix, and probably candidate for -stable.
Oleg.
net/core/pktgen.c | 9 ++-------
1 files changed, 2 insertions(+), 7 deletions(-)
^ permalink raw reply [flat|nested] 5+ messages in thread
* [PATCH 1/2] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop()
2015-07-08 19:41 [PATCH 0/2] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop() Oleg Nesterov
@ 2015-07-08 19:42 ` Oleg Nesterov
2015-07-08 19:42 ` [PATCH 2/2] net: pktgen: kill the "Wait for kthread_stop" code in pktgen_thread_worker() Oleg Nesterov
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Oleg Nesterov @ 2015-07-08 19:42 UTC (permalink / raw)
To: Alexei Starovoitov, David S. Miller, Eric Dumazet
Cc: Jan Stancek, Marcelo Leitner, netdev, linux-kernel
pktgen_thread_worker() is obviously racy, kthread_stop() can come
between the kthread_should_stop() check and set_current_state().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Jan Stancek <jstancek@redhat.com>
Reported-by: Marcelo Leitner <mleitner@redhat.com>
---
net/core/pktgen.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 508155b..043ea18 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -3490,8 +3490,10 @@ static int pktgen_thread_worker(void *arg)
pktgen_rem_thread(t);
/* Wait for kthread_stop */
- while (!kthread_should_stop()) {
+ for (;;) {
set_current_state(TASK_INTERRUPTIBLE);
+ if (kthread_should_stop())
+ break;
schedule();
}
__set_current_state(TASK_RUNNING);
--
1.5.5.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH 2/2] net: pktgen: kill the "Wait for kthread_stop" code in pktgen_thread_worker()
2015-07-08 19:41 [PATCH 0/2] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop() Oleg Nesterov
2015-07-08 19:42 ` [PATCH 1/2] " Oleg Nesterov
@ 2015-07-08 19:42 ` Oleg Nesterov
2015-07-09 22:06 ` [PATCH 0/2] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop() David Miller
2015-07-10 11:32 ` Marcelo Ricardo Leitner
3 siblings, 0 replies; 5+ messages in thread
From: Oleg Nesterov @ 2015-07-08 19:42 UTC (permalink / raw)
To: Alexei Starovoitov, David S. Miller, Eric Dumazet
Cc: Jan Stancek, Marcelo Leitner, netdev, linux-kernel
pktgen_thread_worker() doesn't need to wait for kthread_stop(), it
can simply exit. Just pktgen_create_thread() and pg_net_exit() should
do get_task_struct()/put_task_struct(). kthread_stop(dead_thread) is
fine.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
net/core/pktgen.c | 11 ++---------
1 files changed, 2 insertions(+), 9 deletions(-)
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 043ea18..8e0181a 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -3489,15 +3489,6 @@ static int pktgen_thread_worker(void *arg)
pr_debug("%s removing thread\n", t->tsk->comm);
pktgen_rem_thread(t);
- /* Wait for kthread_stop */
- for (;;) {
- set_current_state(TASK_INTERRUPTIBLE);
- if (kthread_should_stop())
- break;
- schedule();
- }
- __set_current_state(TASK_RUNNING);
-
return 0;
}
@@ -3689,6 +3680,7 @@ static int __net_init pktgen_create_thread(int cpu, struct pktgen_net *pn)
}
t->net = pn;
+ get_task_struct(p);
wake_up_process(p);
wait_for_completion(&t->start_done);
@@ -3811,6 +3803,7 @@ static void __net_exit pg_net_exit(struct net *net)
t = list_entry(q, struct pktgen_thread, th_list);
list_del(&t->th_list);
kthread_stop(t->tsk);
+ put_task_struct(t->tsk);
kfree(t);
}
--
1.5.5.1
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH 0/2] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop()
2015-07-08 19:41 [PATCH 0/2] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop() Oleg Nesterov
2015-07-08 19:42 ` [PATCH 1/2] " Oleg Nesterov
2015-07-08 19:42 ` [PATCH 2/2] net: pktgen: kill the "Wait for kthread_stop" code in pktgen_thread_worker() Oleg Nesterov
@ 2015-07-09 22:06 ` David Miller
2015-07-10 11:32 ` Marcelo Ricardo Leitner
3 siblings, 0 replies; 5+ messages in thread
From: David Miller @ 2015-07-09 22:06 UTC (permalink / raw)
To: oleg; +Cc: ast, edumazet, jstancek, mleitner, netdev, linux-kernel
From: Oleg Nesterov <oleg@redhat.com>
Date: Wed, 8 Jul 2015 21:41:54 +0200
> I am not familiar with this code and I have no idea how to test
> these changes, so 2/2 comes as a separate change. 1/2 looks like
> the obvious bugfix, and probably candidate for -stable.
These look fine to me, applied and patch #1 queued up for -stable.
Thanks.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH 0/2] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop()
2015-07-08 19:41 [PATCH 0/2] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop() Oleg Nesterov
` (2 preceding siblings ...)
2015-07-09 22:06 ` [PATCH 0/2] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop() David Miller
@ 2015-07-10 11:32 ` Marcelo Ricardo Leitner
3 siblings, 0 replies; 5+ messages in thread
From: Marcelo Ricardo Leitner @ 2015-07-10 11:32 UTC (permalink / raw)
To: Oleg Nesterov
Cc: Alexei Starovoitov, David S. Miller, Eric Dumazet, Jan Stancek,
netdev, linux-kernel
On Wed, Jul 08, 2015 at 09:41:54PM +0200, Oleg Nesterov wrote:
> Hello,
>
> I am not familiar with this code and I have no idea how to test
> these changes, so 2/2 comes as a separate change. 1/2 looks like
> the obvious bugfix, and probably candidate for -stable.
>
> Oleg.
>
> net/core/pktgen.c | 9 ++-------
> 1 files changed, 2 insertions(+), 7 deletions(-)
>
Both patches tested here, works for me.
Thanks,
Marcelo
^ permalink raw reply [flat|nested] 5+ messages in thread
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2015-07-08 19:41 [PATCH 0/2] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop() Oleg Nesterov
2015-07-08 19:42 ` [PATCH 1/2] " Oleg Nesterov
2015-07-08 19:42 ` [PATCH 2/2] net: pktgen: kill the "Wait for kthread_stop" code in pktgen_thread_worker() Oleg Nesterov
2015-07-09 22:06 ` [PATCH 0/2] net: pktgen: fix race between pktgen_thread_worker() and kthread_stop() David Miller
2015-07-10 11:32 ` Marcelo Ricardo Leitner
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