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Fix an off-by-one error when deciding to request a tx interrupt

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The canonical check for whether or not a ring is drainable is
TXQ_AVAIL() > MAX_TX_DESC() + 2.  Use this same construct here,
in order to avoid a potential off-by-one error where we might otherwise
fail to request an interrupt.

Reviewed by:	mmacy
Sponsored by:	Netflix
This commit is contained in:
Andrew Gallatin 2018-05-07 18:11:22 +00:00
parent f185a3dc33
commit 1f7ce05d1d
1 changed files with 1 additions and 1 deletions
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2
sys/net/iflib.c
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@ -3299,7 +3299,7 @@ iflib_encap(iflib_txq_t txq, struct mbuf **m_headp)
*/
txq->ift_rs_pending += nsegs + 1;
if (txq->ift_rs_pending > TXQ_MAX_RS_DEFERRED(txq) ||
iflib_no_tx_batch || (TXQ_AVAIL(txq) - nsegs - 1) <= MAX_TX_DESC(ctx)) {
iflib_no_tx_batch || (TXQ_AVAIL(txq) - nsegs) <= MAX_TX_DESC(ctx) + 2) {
pi.ipi_flags |= IPI_TX_INTR;
txq->ift_rs_pending = 0;
}