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Subject[PATCH 2/4] pktgen: make sure that pktgen_thread_worker has been executed
Date
The following courruption can happen during pktgen stop:
list_del corruption. prev->next should be ffff81007e8a5e70, but was 6b6b6b6b6b6b6b6b
kernel BUG at lib/list_debug.c:67!
:pktgen:pktgen_thread_worker+0x374/0x10b0
? autoremove_wake_function+0x0/0x40
? _spin_unlock_irqrestore+0x42/0x80
? :pktgen:pktgen_thread_worker+0x0/0x10b0
kthread+0x4d/0x80
child_rip+0xa/0x12
? restore_args+0x0/0x30
? kthread+0x0/0x80
? child_rip+0x0/0x12
RIP list_del+0x48/0x70
The problem is that pktgen_thread_worker can not be executed if kthread_stop
has been called too early. Insert a completion on the normal initialization
path to make sure that pktgen_thread_worker will gain the control for sure.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Robert Olsson <robert.olsson@its.uu.se>
Cc: Ben Greear <greearb@candelatech.com>
Acked-by: Alexey Dobriyan <adobriyan@openvz.org>
---
net/core/pktgen.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 8dca211..fdf5377 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -390,6 +390,7 @@ struct pktgen_thread {
int cpu;

wait_queue_head_t queue;
+ struct completion start_done;
};

#define REMOVE 1
@@ -3414,6 +3415,7 @@ static int pktgen_thread_worker(void *arg)
BUG_ON(smp_processor_id() != cpu);

init_waitqueue_head(&t->queue);
+ complete(&t->start_done);

pr_debug("pktgen: starting pktgen/%d: pid=%d\n", cpu, task_pid_nr(current));

@@ -3615,6 +3617,7 @@ static int __init pktgen_create_thread(int cpu)
INIT_LIST_HEAD(&t->if_list);

list_add_tail(&t->th_list, &pktgen_threads);
+ init_completion(&t->start_done);

p = kthread_create(pktgen_thread_worker, t, "kpktgend_%d", cpu);
if (IS_ERR(p)) {
@@ -3639,6 +3642,7 @@ static int __init pktgen_create_thread(int cpu)
}

wake_up_process(p);
+ wait_for_completion(&t->start_done);

return 0;
}
--
1.5.3.rc5


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