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 <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>
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 6e13f26..88cfc61 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -310,8 +310,6 @@
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 @@
{
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 @@
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);
}