This patch publishes maximum number of tun/tap queues allocated as a read_only module parameter which a user space application like libvirt can make use of to limit maximum number of queues. Value of read_only module parameter can be writable only at module load time. If no value is set at module load time a default value 256 is used which is equal to maximum number of vCPUS allowed by KVM.
Administrator can specify maximum number of queues only at the driver module load time. Signed-off-by: Pankaj Gupta <[email protected]> --- drivers/net/tun.c | 13 +++++++++++-- 1 files changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index acaaf67..1f518e2 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -119,6 +119,9 @@ struct tap_filter { #define TUN_FLOW_EXPIRE (3 * HZ) +static int max_tap_queues = MAX_TAP_QUEUES; +module_param(max_tap_queues, int, S_IRUGO); + /* A tun_file connects an open character device to a tuntap netdevice. It * also contains all socket related structures (except sock_fprog and tap_filter) * to serve as one transmit queue for tuntap device. The sock_fprog and @@ -545,7 +548,7 @@ static int tun_attach(struct tun_struct *tun, struct file *file, bool skip_filte err = -E2BIG; if (!tfile->detached && - tun->numqueues + tun->numdisabled == MAX_TAP_QUEUES) + tun->numqueues + tun->numdisabled == max_tap_queues) goto out; err = 0; @@ -1609,7 +1612,7 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr) char *name; unsigned long flags = 0; int queues = ifr->ifr_flags & IFF_MULTI_QUEUE ? - MAX_TAP_QUEUES : 1; + max_tap_queues : 1; if (!ns_capable(net->user_ns, CAP_NET_ADMIN)) return -EPERM; @@ -2327,6 +2330,12 @@ static int __init tun_init(void) pr_info("%s, %s\n", DRV_DESCRIPTION, DRV_VERSION); pr_info("%s\n", DRV_COPYRIGHT); + if (max_tap_queues > MAX_TAP_QUEUES || max_tap_queues <= 0) { + printk(KERN_WARNING "max_tap_queues parameter value either too large" + " or too small forcing default value: %d\n", MAX_TAP_QUEUES); + max_tap_queues = MAX_TAP_QUEUES; + } + ret = rtnl_link_register(&tun_link_ops); if (ret) { pr_err("Can't register link_ops\n"); -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
