| Message ID | 20200722085747.6514-1-jasowang@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [1/2] net: forbid the reentrant RX | expand |
On 2020/9/2 下午11:56, Alexander Bulekov wrote: > On 200728 1200, Jason Wang wrote: >> On 2020/7/22 下午4:57, Jason Wang wrote: >>> The memory API allows DMA into NIC's MMIO area. This means the NIC's >>> RX routine must be reentrant. Instead of auditing all the NIC, we can >>> simply detect the reentrancy and return early. The queue->delivering >>> is set and cleared by qemu_net_queue_deliver() for other queue helpers >>> to know whether the delivering in on going (NIC's receive is being >>> called). We can check it and return early in qemu_net_queue_flush() to >>> forbid reentrant RX. >>> >>> Signed-off-by: Jason Wang <jasowang@redhat.com> >>> --- >>> net/queue.c | 3 +++ >>> 1 file changed, 3 insertions(+) >>> >>> diff --git a/net/queue.c b/net/queue.c >>> index 0164727e39..19e32c80fd 100644 >>> --- a/net/queue.c >>> +++ b/net/queue.c >>> @@ -250,6 +250,9 @@ void qemu_net_queue_purge(NetQueue *queue, NetClientState *from) >>> bool qemu_net_queue_flush(NetQueue *queue) >>> { >>> + if (queue->delivering) >>> + return false; >>> + >>> while (!QTAILQ_EMPTY(&queue->packets)) { >>> NetPacket *packet; >>> int ret; >> >> Queued for rc2. >> >> Thanks >> > Hi Jason, > I don't think this ever made it in. Are there any remaining problems? > Thanks > -Alex Hi Alex: It should have been merged: https://git.qemu.org/?p=qemu.git;a=commit;h=22dc8663d9fc7baa22100544c600b6285a63c7a3 Thanks >
diff --git a/net/queue.c b/net/queue.c index 0164727e39..19e32c80fd 100644 --- a/net/queue.c +++ b/net/queue.c @@ -250,6 +250,9 @@ void qemu_net_queue_purge(NetQueue *queue, NetClientState *from) bool qemu_net_queue_flush(NetQueue *queue) { + if (queue->delivering) + return false; + while (!QTAILQ_EMPTY(&queue->packets)) { NetPacket *packet; int ret;
The memory API allows DMA into NIC's MMIO area. This means the NIC's RX routine must be reentrant. Instead of auditing all the NIC, we can simply detect the reentrancy and return early. The queue->delivering is set and cleared by qemu_net_queue_deliver() for other queue helpers to know whether the delivering in on going (NIC's receive is being called). We can check it and return early in qemu_net_queue_flush() to forbid reentrant RX. Signed-off-by: Jason Wang <jasowang@redhat.com> --- net/queue.c | 3 +++ 1 file changed, 3 insertions(+)