From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56864) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZFbsF-0001va-S8 for qemu-devel@nongnu.org; Thu, 16 Jul 2015 01:38:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZFbsB-0001c2-Lw for qemu-devel@nongnu.org; Thu, 16 Jul 2015 01:38:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33732) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZFbsB-0001bv-E7 for qemu-devel@nongnu.org; Thu, 16 Jul 2015 01:38:19 -0400 Message-ID: <55A74343.40507@redhat.com> Date: Thu, 16 Jul 2015 13:38:11 +0800 From: Jason Wang MIME-Version: 1.0 References: <1436955553-22791-1-git-send-email-famz@redhat.com> <1436955553-22791-13-git-send-email-famz@redhat.com> <55A71DE2.3060205@redhat.com> <20150716033247.GB10334@ad.nay.redhat.com> In-Reply-To: <20150716033247.GB10334@ad.nay.redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 for-2.4 12/12] axienet: Flush queued packets when rx is done List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: Peter Maydell , Peter Crosthwaite , Rob Herring , qemu-devel@nongnu.org, Michael Walle , Gerd Hoffmann , stefanha@redhat.com, "Edgar E. Iglesias" On 07/16/2015 11:32 AM, Fam Zheng wrote: > On Thu, 07/16 10:58, Jason Wang wrote: >> >> On 07/15/2015 06:19 PM, Fam Zheng wrote: >>> eth_can_rx checks s->rxsize and returns false if it is non-zero. Because >>> of the .can_receive semantics change, this will make the incoming queue >>> disabled by peer, until it is explicitly flushed. So we should flush it >>> when s->rxsize is becoming zero. >>> >>> Squash eth_can_rx semantics into etx_rx and drop .can_receive() >>> callback, also add flush when rx buffer becomes available again after a >>> packet gets queued. >>> >>> The other conditions, "!axienet_rx_resetting(s) && >>> axienet_rx_enabled(s)" are OK because enet_write already calls >>> qemu_flush_queued_packets when the register bits are changed. >>> >>> Signed-off-by: Fam Zheng >>> --- >>> hw/net/xilinx_axienet.c | 17 +++++++++++++---- >>> 1 file changed, 13 insertions(+), 4 deletions(-) >>> >>> diff --git a/hw/net/xilinx_axienet.c b/hw/net/xilinx_axienet.c >>> index 9205770..d63c423 100644 >>> --- a/hw/net/xilinx_axienet.c >>> +++ b/hw/net/xilinx_axienet.c >>> @@ -401,6 +401,9 @@ struct XilinxAXIEnet { >>> >>> uint8_t rxapp[CONTROL_PAYLOAD_SIZE]; >>> uint32_t rxappsize; >>> + >>> + /* Whether axienet_eth_rx_notify should flush incoming queue. */ >>> + bool need_flush; >>> }; >>> >>> static void axienet_rx_reset(XilinxAXIEnet *s) >>> @@ -658,10 +661,8 @@ static const MemoryRegionOps enet_ops = { >>> .endianness = DEVICE_LITTLE_ENDIAN, >>> }; >>> >>> -static int eth_can_rx(NetClientState *nc) >>> +static int eth_can_rx(XilinxAXIEnet *s) >>> { >>> - XilinxAXIEnet *s = qemu_get_nic_opaque(nc); >>> - >>> /* RX enabled? */ >>> return !s->rxsize && !axienet_rx_resetting(s) && axienet_rx_enabled(s); >>> } >>> @@ -701,6 +702,10 @@ static void axienet_eth_rx_notify(void *opaque) >>> s->rxpos += ret; >>> if (!s->rxsize) { >>> s->regs[R_IS] |= IS_RX_COMPLETE; >>> + if (s->need_flush) { >>> + s->need_flush = false; >>> + qemu_flush_queued_packets(qemu_get_queue(s->nic)); >>> + } >>> } >>> } >>> enet_update_irq(s); >>> @@ -721,6 +726,11 @@ static ssize_t eth_rx(NetClientState *nc, const uint8_t *buf, size_t size) >>> >>> DENET(qemu_log("%s: %zd bytes\n", __func__, size)); >>> >>> + if (!eth_can_rx(s)) { >>> + s->need_flush = true; >>> + return 0; >>> + } >>> + >> axienet_eth_rx_notify() was only called by eth_rx(). So when >> s->need_flush is true, we won't ever reach axienet_eth_rx_notify()? > We will. > > If we are here it measn a previous call to axienet_eth_rx_notify hasn't drained > the buffer: > > static void axienet_eth_rx_notify(void *opaque) > { > ... > > while (s->rxsize && stream_can_push(s->tx_data_dev, > axienet_eth_rx_notify, s)) { > size_t ret = stream_push(s->tx_data_dev, (void *)s->rxmem + s->rxpos, > s->rxsize); > s->rxsize -= ret; > s->rxpos += ret; > if (!s->rxsize) { > s->regs[R_IS] |= IS_RX_COMPLETE; > } > } > ... > > } > > axienet_eth_rx_notify is passed to stream_can_push so it will be reached again > once s->tx_data_dev can receive more data: > > typedef struct StreamSlaveClass { > InterfaceClass parent; > /** > * can push - determine if a stream slave is capable of accepting at least > * one byte of data. Returns false if cannot accept. If not implemented, the > * slave is assumed to always be capable of receiving. > * @notify: Optional callback that the slave will call when the slave is > * capable of receiving again. Only called if false is returned. > * @notify_opaque: opaque data to pass to notify call. > */ > bool (*can_push)(StreamSlave *obj, StreamCanPushNotifyFn notify, > void *notify_opaque); > ... > > Am I missing anything? > > Fam Probably not. I misses the possible call in axidma_write(). So the patch is ok :)