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 <pet...@infradead.org>
Signed-off-by: Fabian Frederick <f...@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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