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[Qemu-devel] Re: [PATCH] net: Fix send queue ordering
From: |
Jan Kiszka |
Subject: |
[Qemu-devel] Re: [PATCH] net: Fix send queue ordering |
Date: |
Wed, 26 Aug 2009 12:49:36 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
Jan Kiszka wrote:
> Ensure that packets enqueued for delayed delivery are dequeued in FIFO
> order. At least one simplistic guest TCP/IP stack became unhappy due to
> sporadically reordered packet streams.
Before I forget: This should also be considered for 0.11-rc (it's a 0.11
regression).
>
> At this chance, switch the send queue implementation to TAILQ.
>
> Signed-off-by: Jan Kiszka <address@hidden>
> ---
>
> net.c | 29 ++++++++++++-----------------
> net.h | 5 +++--
> 2 files changed, 15 insertions(+), 19 deletions(-)
>
> diff --git a/net.c b/net.c
> index 1b531e7..d7a1ab6 100644
> --- a/net.c
> +++ b/net.c
> @@ -436,33 +436,28 @@ qemu_deliver_packet(VLANClientState *sender, const
> uint8_t *buf, int size)
>
> void qemu_purge_queued_packets(VLANClientState *vc)
> {
> - VLANPacket **pp = &vc->vlan->send_queue;
> -
> - while (*pp != NULL) {
> - VLANPacket *packet = *pp;
> + VLANPacket *packet, *next;
>
> + TAILQ_FOREACH_SAFE(packet, &vc->vlan->send_queue, entry, next) {
> if (packet->sender == vc) {
> - *pp = packet->next;
> + TAILQ_REMOVE(&vc->vlan->send_queue, packet, entry);
> qemu_free(packet);
> - } else {
> - pp = &packet->next;
> }
> }
> }
>
> void qemu_flush_queued_packets(VLANClientState *vc)
> {
> - VLANPacket *packet;
> -
> - while ((packet = vc->vlan->send_queue) != NULL) {
> + while (!TAILQ_EMPTY(&vc->vlan->send_queue)) {
> + VLANPacket *packet;
> int ret;
>
> - vc->vlan->send_queue = packet->next;
> + packet = TAILQ_FIRST(&vc->vlan->send_queue);
> + TAILQ_REMOVE(&vc->vlan->send_queue, packet, entry);
>
> ret = qemu_deliver_packet(packet->sender, packet->data,
> packet->size);
> if (ret == 0 && packet->sent_cb != NULL) {
> - packet->next = vc->vlan->send_queue;
> - vc->vlan->send_queue = packet;
> + TAILQ_INSERT_HEAD(&vc->vlan->send_queue, packet, entry);
> break;
> }
>
> @@ -480,12 +475,12 @@ static void qemu_enqueue_packet(VLANClientState *sender,
> VLANPacket *packet;
>
> packet = qemu_malloc(sizeof(VLANPacket) + size);
> - packet->next = sender->vlan->send_queue;
> packet->sender = sender;
> packet->size = size;
> packet->sent_cb = sent_cb;
> memcpy(packet->data, buf, size);
> - sender->vlan->send_queue = packet;
> +
> + TAILQ_INSERT_TAIL(&sender->vlan->send_queue, packet, entry);
> }
>
> ssize_t qemu_send_packet_async(VLANClientState *sender,
> @@ -597,7 +592,6 @@ static ssize_t qemu_enqueue_packet_iov(VLANClientState
> *sender,
> max_len = calc_iov_length(iov, iovcnt);
>
> packet = qemu_malloc(sizeof(VLANPacket) + max_len);
> - packet->next = sender->vlan->send_queue;
> packet->sender = sender;
> packet->sent_cb = sent_cb;
> packet->size = 0;
> @@ -609,7 +603,7 @@ static ssize_t qemu_enqueue_packet_iov(VLANClientState
> *sender,
> packet->size += len;
> }
>
> - sender->vlan->send_queue = packet;
> + TAILQ_INSERT_TAIL(&sender->vlan->send_queue, packet, entry);
>
> return packet->size;
> }
> @@ -2330,6 +2324,7 @@ VLANState *qemu_find_vlan(int id, int allocate)
> }
> vlan = qemu_mallocz(sizeof(VLANState));
> vlan->id = id;
> + TAILQ_INIT(&vlan->send_queue);
> vlan->next = NULL;
> pvlan = &first_vlan;
> while (*pvlan != NULL)
> diff --git a/net.h b/net.h
> index 3ac9e8c..bab02f5 100644
> --- a/net.h
> +++ b/net.h
> @@ -1,6 +1,7 @@
> #ifndef QEMU_NET_H
> #define QEMU_NET_H
>
> +#include "sys-queue.h"
> #include "qemu-common.h"
>
> /* VLANs support */
> @@ -35,7 +36,7 @@ typedef struct VLANPacket VLANPacket;
> typedef void (NetPacketSent) (VLANClientState *, ssize_t);
>
> struct VLANPacket {
> - struct VLANPacket *next;
> + TAILQ_ENTRY(VLANPacket) entry;
> VLANClientState *sender;
> int size;
> NetPacketSent *sent_cb;
> @@ -47,7 +48,7 @@ struct VLANState {
> VLANClientState *first_client;
> struct VLANState *next;
> unsigned int nb_guest_devs, nb_host_devs;
> - VLANPacket *send_queue;
> + TAILQ_HEAD(send_queue, VLANPacket) send_queue;
> int delivering;
> };
>
>
Jan
--
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux