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Commit aa75db00 authored by Dan Williams's avatar Dan Williams
Browse files

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: default avatarDan Williams <dan.j.williams@intel.com>
parent 281befa5

drivers/dma/ioat/dma_v2.c

+1 −1
Original line number Diff line number Diff line
@@ -158,7 +158,7 @@ static void __cleanup(struct ioat2_dma_chan *ioat, unsigned long phys_complete) 
			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) {

drivers/dma/ioat/dma_v3.c

+1 −1
Original line number Diff line number Diff line
@@ -293,7 +293,7 @@ static void __cleanup(struct ioat2_dma_chan *ioat, unsigned long phys_complete) 
		}

	}

	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) {

		dev_dbg(to_dev(chan), "%s: cancel completion timeout\n",