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dmaengine: pl330: fix irq race with terminate_all 

In pl330_update() when checking if a channel has been aborted, the
channel's lock is not taken, only the overall pl330_dmac lock.  But in
pl330_terminate_all() the aborted flag (req_running==-1) is set under
the channel lock and not the pl330_dmac lock.

With threaded interrupts, this leads to a potential race:

    pl330_terminate_all	        pl330_update
    -------------------         ------------
    lock channel
                                entry
    lock pl330
    _stop channel
    unlock pl330
                                lock pl330
                                check req_running != -1
    req_running = -1
                                _start channel

Signed-off-by: John Keeping <john@metanate.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
hifive-unleashed-5.1
John Keeping 2018-07-17 11:48:16 +01:00 committed by Vinod Koul
parent 2f903bab92
commit e49756544a
1 changed files with 3 additions and 2 deletions
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5
drivers/dma/pl330.c
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@ -2256,13 +2256,14 @@ static int pl330_terminate_all(struct dma_chan *chan)
pm_runtime_get_sync(pl330->ddma.dev);
spin_lock_irqsave(&pch->lock, flags);
spin_lock(&pl330->lock);
_stop(pch->thread);
spin_unlock(&pl330->lock);
pch->thread->req[0].desc = NULL;
pch->thread->req[1].desc = NULL;
pch->thread->req_running = -1;
spin_unlock(&pl330->lock);
power_down = pch->active;
pch->active = false;