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Commit d202f051 authored by Ludovic Desroches's avatar Ludovic Desroches Committed by Linus Torvalds
Browse files

dmaengine: at_hdmac: fix race condition in atc_advance_work() 



The BUG_ON() directive is triggered probably due to a latency
modification following inclusion of commit c10d7367 ("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: default avatarLudovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: default avatarNicolas Ferre <nicolas.ferre@atmel.com>
Acked-by: default avatarVinod Koul <vinod.koul@intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent ebe80544

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);

}