[Qemu-devel] [PATCH 33/60] e1000: drop check_rxov, always treat RX ring with RDH == RDT as empty

[Michael Tokarev]

From: Dmitry Fleytman <address@hidden>

Real HW always treats RX ring with RDH == RDT as empty.
Emulation is supposed to behave the same.

Reported-by: Chris Webb <address@hidden>
Reported-by: Richard Davies <address@hidden>
Signed-off-by: Dmitry Fleytman <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
(cherry picked from commit e5b8b0d4ba29fe1268ba049519a1b0cf8552a21a)

Signed-off-by: Michael Tokarev <address@hidden>
---
 hw/e1000.c |    7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/hw/e1000.c b/hw/e1000.c
index 43d933a..d3a15e5 100644
--- a/hw/e1000.c
+++ b/hw/e1000.c
@@ -92,7 +92,6 @@ typedef struct E1000State_st {
 
     uint32_t rxbuf_size;
     uint32_t rxbuf_min_shift;
-    int check_rxov;
     struct e1000_tx {
         unsigned char header[256];
         unsigned char vlan_header[4];
@@ -741,11 +740,11 @@ static bool e1000_has_rxbufs(E1000State *s, size_t 
total_size)
     int bufs;
     /* Fast-path short packets */
     if (total_size <= s->rxbuf_size) {
-        return s->mac_reg[RDH] != s->mac_reg[RDT] || !s->check_rxov;
+        return s->mac_reg[RDH] != s->mac_reg[RDT];
     }
     if (s->mac_reg[RDH] < s->mac_reg[RDT]) {
         bufs = s->mac_reg[RDT] - s->mac_reg[RDH];
-    } else if (s->mac_reg[RDH] > s->mac_reg[RDT] || !s->check_rxov) {
+    } else if (s->mac_reg[RDH] > s->mac_reg[RDT]) {
         bufs = s->mac_reg[RDLEN] /  sizeof(struct e1000_rx_desc) +
             s->mac_reg[RDT] - s->mac_reg[RDH];
     } else {
@@ -848,7 +847,6 @@ e1000_receive(VLANClientState *nc, const uint8_t *buf, 
size_t size)
 
         if (++s->mac_reg[RDH] * sizeof(desc) >= s->mac_reg[RDLEN])
             s->mac_reg[RDH] = 0;
-        s->check_rxov = 1;
         /* see comment in start_xmit; same here */
         if (s->mac_reg[RDH] == rdh_start) {
             DBGOUT(RXERR, "RDH wraparound @%x, RDT %x, RDLEN %x\n",
@@ -925,7 +923,6 @@ mac_writereg(E1000State *s, int index, uint32_t val)
 static void
 set_rdt(E1000State *s, int index, uint32_t val)
 {
-    s->check_rxov = 0;
     s->mac_reg[index] = val & 0xffff;
     if (e1000_has_rxbufs(s, 1)) {
         qemu_flush_queued_packets(&s->nic->nc);
-- 
1.7.10.4