Commit e4975654 authored Jul 17, 2018 by John Keeping Committed by Vinod Koul Jul 25, 2018

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>

parent 2f903bab

drivers/dma/pl330.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -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;

Admin message