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[v2,1/4] dma/idxd: fix burst capacity calculation

Message ID 20220111134105.1007191-2-bruce.richardson@intel.com (mailing list archive)
State Accepted, archived
Delegated to: Thomas Monjalon
Headers show
Series fixes for dma/idxd | expand


Context Check Description
ci/checkpatch success coding style OK

Commit Message

Bruce Richardson Jan. 11, 2022, 1:41 p.m. UTC
When the maximum burst size supported by HW is less than the available
ring space, incorrect capacity was returned when there was already some
jobs queued up for submission. This was because the capacity calculation
failed to subtract the number of already-enqueued jobs from the max
burst size. After subtraction is done, ensure that any negative values
(which should never occur if the user respects the reported limits), are
clamped to zero.

Fixes: 9459de4edc99 ("dma/idxd: add burst capacity")
Cc: kevin.laatz@intel.com
Cc: stable@dpdk.org

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Kevin Laatz <kevin.laatz@intel.com>
Tested-by: Jiayu Hu <jiayu.hu@intel.com>
 drivers/dma/idxd/idxd_common.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
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diff --git a/drivers/dma/idxd/idxd_common.c b/drivers/dma/idxd/idxd_common.c
index fc11b11337..4442d1cbbd 100644
--- a/drivers/dma/idxd/idxd_common.c
+++ b/drivers/dma/idxd/idxd_common.c
@@ -485,7 +485,9 @@  idxd_burst_capacity(const void *dev_private, uint16_t vchan __rte_unused)
 		write_idx += idxd->desc_ring_mask + 1;
 	used_space = write_idx - idxd->ids_returned;
-	return RTE_MIN((idxd->desc_ring_mask - used_space), idxd->max_batch_size);
+	const int ret = RTE_MIN((idxd->desc_ring_mask - used_space),
+			(idxd->max_batch_size - idxd->batch_size));
+	return ret < 0 ? 0 : (uint16_t)ret;