dmaengine: at_hdmac: fix race condition in atc_advance_work() (d202f051) · Commits · 戴 / test

The BUG_ON() directive is triggered probably due to a latency modification following inclusion of commit ("softirq: reduce latencies"). This condition has not been met before 3.9-rc1 and doesn't trigger without this patch. We now make sure that DMA channel is idle before calling atc_complete_all() which makes the BUG_ON() "protection" useless. Signed-off-by:

Ludovic Desroches <ludovic.desroches@atmel.com> Signed-off-by:

Nicolas Ferre <nicolas.ferre@atmel.com> Acked-by:

Vinod Koul <vinod.koul@intel.com> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

drivers/dma/at_hdmac.c

+4 −5

Original line number	Diff line number	Diff line
		@@ -310,8 +310,6 @@ static void atc_complete_all(struct at_dma_chan *atchan)

		dev_vdbg(chan2dev(&atchan->chan_common), "complete all\n");

		BUG_ON(atc_chan_is_enabled(atchan));

		/*
		* Submit queued descriptors ASAP, i.e. before we go through
		* the completed ones.
		@@ -368,6 +366,9 @@ static void atc_advance_work(struct at_dma_chan *atchan)
		{
		dev_vdbg(chan2dev(&atchan->chan_common), "advance_work\n");

		if (atc_chan_is_enabled(atchan))
		return;

		if (list_empty(&atchan->active_list) \|\|
		list_is_singular(&atchan->active_list)) {
		atc_complete_all(atchan);
		@@ -1078,9 +1079,7 @@ static void atc_issue_pending(struct dma_chan *chan)
		return;

		spin_lock_irqsave(&atchan->lock, flags);
		if (!atc_chan_is_enabled(atchan)) {
		atc_advance_work(atchan);
		}
		spin_unlock_irqrestore(&atchan->lock, flags);
		}

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