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    Subject[PATCH 6/7 linux-next] wan: cosa: replace current->state by set_current_state()
    Date
    Use helper functions to access current->state.
    Direct assignments are prone to races and therefore buggy.

    current->state = TASK_RUNNING is replaced by __set_current_state()

    Thanks to Peter Zijlstra for the exact definition of the problem.

    Suggested-By: Peter Zijlstra <peterz@infradead.org>
    Signed-off-by: Fabian Frederick <fabf@skynet.be>
    ---
    drivers/net/wan/cosa.c | 12 ++++++------
    1 file changed, 6 insertions(+), 6 deletions(-)

    diff --git a/drivers/net/wan/cosa.c b/drivers/net/wan/cosa.c
    index 83c39e2..88d121d 100644
    --- a/drivers/net/wan/cosa.c
    +++ b/drivers/net/wan/cosa.c
    @@ -806,21 +806,21 @@ static ssize_t cosa_read(struct file *file,
    spin_lock_irqsave(&cosa->lock, flags);
    add_wait_queue(&chan->rxwaitq, &wait);
    while (!chan->rx_status) {
    - current->state = TASK_INTERRUPTIBLE;
    + set_current_state(TASK_INTERRUPTIBLE);
    spin_unlock_irqrestore(&cosa->lock, flags);
    schedule();
    spin_lock_irqsave(&cosa->lock, flags);
    if (signal_pending(current) && chan->rx_status == 0) {
    chan->rx_status = 1;
    remove_wait_queue(&chan->rxwaitq, &wait);
    - current->state = TASK_RUNNING;
    + __set_current_state(TASK_RUNNING);
    spin_unlock_irqrestore(&cosa->lock, flags);
    mutex_unlock(&chan->rlock);
    return -ERESTARTSYS;
    }
    }
    remove_wait_queue(&chan->rxwaitq, &wait);
    - current->state = TASK_RUNNING;
    + __set_current_state(TASK_RUNNING);
    kbuf = chan->rxdata;
    count = chan->rxsize;
    spin_unlock_irqrestore(&cosa->lock, flags);
    @@ -890,14 +890,14 @@ static ssize_t cosa_write(struct file *file,
    spin_lock_irqsave(&cosa->lock, flags);
    add_wait_queue(&chan->txwaitq, &wait);
    while (!chan->tx_status) {
    - current->state = TASK_INTERRUPTIBLE;
    + set_current_state(TASK_INTERRUPTIBLE);
    spin_unlock_irqrestore(&cosa->lock, flags);
    schedule();
    spin_lock_irqsave(&cosa->lock, flags);
    if (signal_pending(current) && chan->tx_status == 0) {
    chan->tx_status = 1;
    remove_wait_queue(&chan->txwaitq, &wait);
    - current->state = TASK_RUNNING;
    + __set_current_state(TASK_RUNNING);
    chan->tx_status = 1;
    spin_unlock_irqrestore(&cosa->lock, flags);
    up(&chan->wsem);
    @@ -905,7 +905,7 @@ static ssize_t cosa_write(struct file *file,
    }
    }
    remove_wait_queue(&chan->txwaitq, &wait);
    - current->state = TASK_RUNNING;
    + __set_current_state(TASK_RUNNING);
    up(&chan->wsem);
    spin_unlock_irqrestore(&cosa->lock, flags);
    kfree(kbuf);
    --
    2.1.0


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