| Message ID | 20171113152702.14686-1-simon.guinot@sequanux.org |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | [v2] net: mvneta: fix handling of the Tx descriptor counter | expand |
From: Simon Guinot <simon.guinot@sequanux.org> Date: Mon, 13 Nov 2017 16:27:02 +0100 > The mvneta controller provides a 8-bit register to update the pending > Tx descriptor counter. Then, a maximum of 255 Tx descriptors can be > added at once. In the current code the mvneta_txq_pend_desc_add function > assumes the caller takes care of this limit. But it is not the case. In > some situations (xmit_more flag), more than 255 descriptors are added. > When this happens, the Tx descriptor counter register is updated with a > wrong value, which breaks the whole Tx queue management. > > This patch fixes the issue by allowing the mvneta_txq_pend_desc_add > function to process more than 255 Tx descriptors. > > Fixes: 2a90f7e1d5d0 ("net: mvneta: add xmit_more support") > Cc: stable@vger.kernel.org # 4.11+ > Signed-off-by: Simon Guinot <simon.guinot@sequanux.org> Applied.
diff --git a/drivers/net/ethernet/marvell/mvneta.c b/drivers/net/ethernet/marvell/mvneta.c index 64a04975bcf8..bc93b69cfd1e 100644 --- a/drivers/net/ethernet/marvell/mvneta.c +++ b/drivers/net/ethernet/marvell/mvneta.c @@ -816,11 +816,14 @@ static void mvneta_txq_pend_desc_add(struct mvneta_port *pp, { u32 val; - /* Only 255 descriptors can be added at once ; Assume caller - * process TX desriptors in quanta less than 256 - */ - val = pend_desc + txq->pending; - mvreg_write(pp, MVNETA_TXQ_UPDATE_REG(txq->id), val); + pend_desc += txq->pending; + + /* Only 255 Tx descriptors can be added at once */ + do { + val = min(pend_desc, 255); + mvreg_write(pp, MVNETA_TXQ_UPDATE_REG(txq->id), val); + pend_desc -= val; + } while (pend_desc > 0); txq->pending = 0; }
The mvneta controller provides a 8-bit register to update the pending Tx descriptor counter. Then, a maximum of 255 Tx descriptors can be added at once. In the current code the mvneta_txq_pend_desc_add function assumes the caller takes care of this limit. But it is not the case. In some situations (xmit_more flag), more than 255 descriptors are added. When this happens, the Tx descriptor counter register is updated with a wrong value, which breaks the whole Tx queue management. This patch fixes the issue by allowing the mvneta_txq_pend_desc_add function to process more than 255 Tx descriptors. Fixes: 2a90f7e1d5d0 ("net: mvneta: add xmit_more support") Cc: stable@vger.kernel.org # 4.11+ Signed-off-by: Simon Guinot <simon.guinot@sequanux.org> --- drivers/net/ethernet/marvell/mvneta.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) Changes for v2: - Use do {} while instead of while {}. - Keep "txq->pending + frags > MVNETA_TXQ_DEC_SENT_MASK" as a flushing condition for the Tx queue.