On Fri, Nov 18, 2022 at 12:56 AM Stefan Hajnoczi <stefa...@redhat.com> wrote: > > The device turns the Tx Descriptor into a Tx Status descriptor after > fully reading the descriptor. This involves clearing Tx Own (bit 31) to > indicate that the driver has ownership of the descriptor again as well > as several other bits. > > The code keeps the first dword of the Tx Descriptor in the txdw0 local > variable. txdw0 is reused to build the first word of the Tx Status > descriptor. Later on the code uses txdw0 again, incorrectly assuming > that it still contains the first dword of the Tx Descriptor. The tx > offloading code misbehaves because it sees bogus bits in txdw0.
(This is only noticeable with patch 2). > > Use a separate local variable for Tx Status and preserve Tx Descriptor > in txdw0. > > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> Acked-by: Jason Wang <jasow...@redhat.com> > --- > hw/net/rtl8139.c | 17 ++++++++++------- > 1 file changed, 10 insertions(+), 7 deletions(-) > > diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c > index e6643e3c9d..ffef3789b5 100644 > --- a/hw/net/rtl8139.c > +++ b/hw/net/rtl8139.c > @@ -2027,18 +2027,21 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s) > s->currCPlusTxDesc = 0; > } > > + /* Build the Tx Status Descriptor */ > + uint32_t tx_status = txdw0; > + > /* transfer ownership to target */ > - txdw0 &= ~CP_TX_OWN; > + tx_status &= ~CP_TX_OWN; > > /* reset error indicator bits */ > - txdw0 &= ~CP_TX_STATUS_UNF; > - txdw0 &= ~CP_TX_STATUS_TES; > - txdw0 &= ~CP_TX_STATUS_OWC; > - txdw0 &= ~CP_TX_STATUS_LNKF; > - txdw0 &= ~CP_TX_STATUS_EXC; > + tx_status &= ~CP_TX_STATUS_UNF; > + tx_status &= ~CP_TX_STATUS_TES; > + tx_status &= ~CP_TX_STATUS_OWC; > + tx_status &= ~CP_TX_STATUS_LNKF; > + tx_status &= ~CP_TX_STATUS_EXC; > > /* update ring data */ > - val = cpu_to_le32(txdw0); > + val = cpu_to_le32(tx_status); > pci_dma_write(d, cplus_tx_ring_desc, (uint8_t *)&val, 4); > > /* Now decide if descriptor being processed is holding the last segment > of packet */ > -- > 2.38.1 >
