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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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