Re: [libvirt] [PATCH 1/2] rpc: Switch to dynamically allocated message buffer

Currently, we are allocating buffer for RPC messages statically. This is not such pain when RPC limits are small. However, if we want ever to increase those limits, we need to allocate buffer dynamically, based on RPC message len (= the first 4 bytes). Therefore we will decrease our mem usage in most cases and still be flexible enough in corner cases. --- src/rpc/virnetclient.c | 16 ++- src/rpc/virnetmessage.c | 12 ++- src/rpc/virnetmessage.h | 6 +- src/rpc/virnetserverclient.c | 20 ++- tests/virnetmessagetest.c | 393 +++++++++++++++++++++++-------------------

5 files changed, 264 insertions(+), 183 deletions(-) +++ b/src/rpc/virnetmessage.h @@ -31,13 +31,11 @@ typedef virNetMessage *virNetMessagePtr; typedef void (*virNetMessageFreeCallback)(virNetMessagePtr msg, void *opaque); -/* Never allocate this (huge) buffer on the stack. Always - * use virNetMessageNew() to allocate on the heap - */ struct _virNetMessage { bool tracked; - char buffer[VIR_NET_MESSAGE_MAX + VIR_NET_MESSAGE_LEN_MAX]; + //char buffer[VIR_NET_MESSAGE_MAX + VIR_NET_MESSAGE_LEN_MAX]; + char *buffer;

@@ -373,6 +378,9 @@ virNetServerClientPtr virNetServerClientNew(virNetSocketPtr sock, if (!(client->rx = virNetMessageNew(true))) goto error; client->rx->bufferLength = VIR_NET_MESSAGE_LEN_MAX; + if (VIR_ALLOC_N(client->rx->buffer, client->rx->bufferLength) < 0) { + virReportOOMError(); + }

@@ -922,6 +930,11 @@ readmore: client->wantClose = true; } else { client->rx->bufferLength = VIR_NET_MESSAGE_LEN_MAX; + if (VIR_ALLOC_N(client->rx->buffer, + client->rx->bufferLength) < 0) { + virReportOOMError(); + client->wantClose = true; + } client->nrequests++;