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dmaengine: at_hdmac: fix race condition in atc_advance_work()

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The BUG_ON() directive is triggered probably due to a latency
modification following inclusion of commit c10d73671ad3 ("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>
This commit is contained in:
Ludovic Desroches 2013-04-18 09:52:59 +02:00 committed by Linus Torvalds
parent ebe8054433
commit d202f05158
1 changed files with 4 additions and 5 deletions
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9
drivers/dma/at_hdmac.c
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@ -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);
}
atc_advance_work(atchan);
spin_unlock_irqrestore(&atchan->lock, flags);
}