ioat: close potential BUG_ON race in the descriptor cleanup path
Since ioat_cleanup_preamble() and the update of the last completed
descriptor are not synchronized there is a chance that two cleanup threads
can see descriptors to clean. If the first cleans up all pending
descriptors then the second will trigger the BUG_ON.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/dma/ioat/dma_v2.c b/drivers/dma/ioat/dma_v2.c
index c6e4531..01ed1cf 100644
--- a/drivers/dma/ioat/dma_v2.c
+++ b/drivers/dma/ioat/dma_v2.c
@@ -158,7 +158,7 @@
seen_current = true;
}
ioat->tail += i;
- BUG_ON(!seen_current); /* no active descs have written a completion? */
+ BUG_ON(active && !seen_current); /* no active descs have written a completion? */
chan->last_completion = phys_complete;
if (ioat->head == ioat->tail) {