With this patch, nm_open() does not mmap() the netmap device. This operation is performed separately only if the memory area of the port just opened was not known before. A global list of netmap clients is kept to check when matches occur.
Signed-off-by: Vincenzo Maffione <v.maffi...@gmail.com> --- net/netmap.c | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) diff --git a/net/netmap.c b/net/netmap.c index 27295ab..6a4c01c 100644 --- a/net/netmap.c +++ b/net/netmap.c @@ -49,8 +49,12 @@ typedef struct NetmapState { bool write_poll; struct iovec iov[IOV_MAX]; int vnet_hdr_len; /* Current virtio-net header length. */ + QTAILQ_ENTRY(NetmapState) next; } NetmapState; +static QTAILQ_HEAD(, NetmapState) netmap_clients = + QTAILQ_HEAD_INITIALIZER(netmap_clients); + #ifndef __FreeBSD__ #define pkt_copy bcopy #else @@ -78,6 +82,23 @@ pkt_copy(const void *_src, void *_dst, int l) #endif /* __FreeBSD__ */ /* + * find nm_desc parent with same allocator + */ +static struct nm_desc * +netmap_find_memory(struct nm_desc *nmd) +{ + NetmapState *s; + + QTAILQ_FOREACH(s, &netmap_clients, next) { + if (nmd->req.nr_arg2 == s->nmd->req.nr_arg2) { + return s->nmd; + } + } + + return NULL; +} + +/* * Open a netmap device. We assume there is only one queue * (which is the case for the VALE bridge). */ @@ -86,10 +107,11 @@ static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts, { struct nm_desc *nmd; struct nmreq req; + int ret; memset(&req, 0, sizeof(req)); - nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL, + nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL | NM_OPEN_NO_MMAP, NULL); if (nmd == NULL) { error_setg_errno(errp, errno, "Failed to nm_open() %s", @@ -97,6 +119,17 @@ static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts, return NULL; } + /* Check if we already have a nm_desc that uses the same memory as the one + * just opened, so that nm_mmap() can skip mmap() and inherit from parent. + */ + ret = nm_mmap(nmd, netmap_find_memory(nmd)); + if (ret) { + error_setg_errno(errp, errno, "Failed to nm_mmap() %s", + nm_opts->ifname); + nm_close(nmd); + return NULL; + } + return nmd; } @@ -321,6 +354,8 @@ static void netmap_cleanup(NetClientState *nc) netmap_poll(nc, false); nm_close(s->nmd); s->nmd = NULL; + + QTAILQ_REMOVE(&netmap_clients, s, next); } /* Offloading manipulation support callbacks. */ @@ -423,6 +458,7 @@ int net_init_netmap(const NetClientOptions *opts, s->rx = NETMAP_RXRING(nmd->nifp, 0); s->vnet_hdr_len = 0; pstrcpy(s->ifname, sizeof(s->ifname), netmap_opts->ifname); + QTAILQ_INSERT_TAIL(&netmap_clients, s, next); netmap_read_poll(s, true); /* Initially only poll for reads. */ return 0; -- 2.7.0