From: Ludovic Desroches Date: Thu, 18 Apr 2013 07:52:59 +0000 (+0200) Subject: dmaengine: at_hdmac: fix race condition in atc_advance_work() X-Git-Tag: firefly_0821_release~3680^2~715 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d202f05158442396033f416df376f8ece1f563df;p=firefly-linux-kernel-4.4.55.git 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 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 Signed-off-by: Nicolas Ferre Acked-by: Vinod Koul Signed-off-by: Linus Torvalds --- diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c index 6e13f262139a..88cfc61329d2 100644 --- a/drivers/dma/at_hdmac.c +++ b/drivers/dma/at_hdmac.c @@ -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); }