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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>
This commit is contained in:
Dan Williams 2010-03-03 21:21:10 -07:00
parent 281befa559
commit aa75db0080
2 changed files with 2 additions and 2 deletions
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2
drivers/dma/ioat/dma_v2.c
View File

@ -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) {

2
drivers/dma/ioat/dma_v3.c
View File

@ -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",