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authorFernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>2012-06-04 17:35:11 +0300
committerMichael Roth <mdroth@linux.vnet.ibm.com>2012-06-25 08:54:55 -0500
commit065436479b9164b51892dbd7a7e35a3f9f496894 (patch)
tree3a21b1ba16c2524fc41ac6f44850c30f3e437efb
parentconfigure: Fix build for some versions of glibc (9pfs) (diff)
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rtl8139: honor RxOverflow flag in can_receive method
Some drivers (Linux' 8139too among them) rely on the NIC injecting an interrupt in the event of a receive buffer overflow and, accordingly, set the RxOverflow bit in the interrupt mask. Unfortunately rtl8139's can_receive method ignores the RxOverflow flag, which may lead to a situation where rtl8139 stops receiving packets (can_receive returns 0) when the receive buffer becomes full. If the driver eventually read from the receive buffer or reset the card the emulator could recover from this situation. However some implementations only do this upon receiving an interrupt with either RxOK or RxOverflow set in the ISR; interrupt that will never come because QEMU's flow control mechanisms would prevent rtl8139 from receiving any packet. Letting packets go through when the overflow interrupt is enabled makes the QEMU emulator compliant to the spec and solves the problem. This patch should fix a relatively common (in our experience) network stall observed when running enterprise distros with rtl8139 as the NIC; in some cases the 8139too device driver gets loaded and when under heavy load the network eventually stops working. Reported-by: Hayato Kakuta <kakuta.hayato@oss.ntt.co.jp> Tested-by: Hayato Kakuta <kakuta.hayato@oss.ntt.co.jp> Acked-by: Igor Kovalenko <igor.v.kovalenko@gmail.com> Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> (cherry picked from commit fee9d348ffc5c9f80068086799a948996f633f7e) Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
-rw-r--r--hw/rtl8139.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/hw/rtl8139.c b/hw/rtl8139.c
index eb22d04fa..f6f144b52 100644
--- a/hw/rtl8139.c
+++ b/hw/rtl8139.c
@@ -802,7 +802,7 @@ static int rtl8139_can_receive(VLANClientState *nc)
} else {
avail = MOD2(s->RxBufferSize + s->RxBufPtr - s->RxBufAddr,
s->RxBufferSize);
- return (avail == 0 || avail >= 1514);
+ return (avail == 0 || avail >= 1514 || (s->IntrMask & RxOverflow));
}
}