Messages in this thread Patch in this message | | | Subject | Re: [Patch 3/3] net: reserve ports for applications using fixed port numbers | From | Tetsuo Handa <> | Date | Tue, 13 Apr 2010 22:07:19 +0900 |
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Hello.
Adding Sean Hefty and Roland Dreier as drivers/infiniband/core/cma.c maintainer.
Cong Wang wrote: > Cong Wang wrote: > > Tetsuo Handa wrote: > >> Hello. > >> > >>> --- linux-2.6.orig/drivers/infiniband/core/cma.c > >>> +++ linux-2.6/drivers/infiniband/core/cma.c > >>> @@ -1980,6 +1980,8 @@ retry: > >>> /* FIXME: add proper port randomization per like inet_csk_get_port */ > >>> do { > >>> ret = idr_get_new_above(ps, bind_list, next_port, &port); > >>> + if (!ret && inet_is_reserved_local_port(port)) > >>> + ret = -EAGAIN; > >>> } while ((ret == -EAGAIN) && idr_pre_get(ps, GFP_KERNEL)); > >>> > >>> if (ret) > >>> > >> I think above part is wrong. Below program > > ... > >> This result suggests that above loop will continue until idr_pre_get() fails > >> due to out of memory if all ports were reserved. > >> > >> Also, if idr_get_new_above() returned 0, bind_list (which is a kmalloc()ed > >> pointer) is already installed into a free slot (see comment on > >> idr_get_new_above_int()). Thus, simply calling idr_get_new_above() again will > >> install the same pointer into multiple slots. I guess it will malfunction later. > > > > Thanks for testing! > > > > How about: > > > > + if (!ret && inet_is_reserved_local_port(port)) > > + ret = -EBUSY; > > > > ? So that it will break the loop and return error. > > > > Or use the similar trick: > > int tries = 10; > ... > > if(!ret && inet_is_reserved_local_port(port)) { > if (tries--) > ret = -EAGAIN; > else > ret = -EBUSY; > } > > Any comments? > I don't like above change. Above change makes local port assignment from "likely-succeed" (succeeds if one port is available from thousands of ports) to "unlikely-succeed" (fail if randomly chosen port is already in use). We should repeat for all ranges specified in /proc/sys/net/ipv4/ip_local_port_range .
cma_alloc_any_port() and cma_alloc_port() are almost identical. Thus, I think we can call cma_alloc_port() from cma_alloc_any_port().
Sean and Roland, is below patch correct? inet_is_reserved_local_port() is the new function proposed in this patchset.
--- drivers/infiniband/core/cma.c | 68 ++++++++++++++---------------------------- 1 file changed, 23 insertions(+), 45 deletions(-)
--- linux-2.6.34-rc4.orig/drivers/infiniband/core/cma.c +++ linux-2.6.34-rc4/drivers/infiniband/core/cma.c @@ -79,7 +79,6 @@ static DEFINE_IDR(sdp_ps); static DEFINE_IDR(tcp_ps); static DEFINE_IDR(udp_ps); static DEFINE_IDR(ipoib_ps); -static int next_port; struct cma_device { struct list_head list; @@ -1970,47 +1969,31 @@ err1: static int cma_alloc_any_port(struct idr *ps, struct rdma_id_private *id_priv) { - struct rdma_bind_list *bind_list; - int port, ret, low, high; - - bind_list = kzalloc(sizeof *bind_list, GFP_KERNEL); - if (!bind_list) - return -ENOMEM; - -retry: - /* FIXME: add proper port randomization per like inet_csk_get_port */ - do { - ret = idr_get_new_above(ps, bind_list, next_port, &port); - } while ((ret == -EAGAIN) && idr_pre_get(ps, GFP_KERNEL)); - - if (ret) - goto err1; + static unsigned int last_used_port; + int low, high, remaining; + unsigned int rover; inet_get_local_port_range(&low, &high); - if (port > high) { - if (next_port != low) { - idr_remove(ps, port); - next_port = low; - goto retry; + remaining = (high - low) + 1; + rover = net_random() % remaining + low; + do { + rover++; + if ((rover < low) || (rover > high)) + rover = low; + if (last_used_port != rover && + !inet_is_reserved_local_port(rover) && + !idr_find(ps, (unsigned short) rover) && + !cma_alloc_port(ps, id_priv, rover)) { + /* + * Remember previously used port number in order to + * avoid re-using same port immediately after it is + * closed. + */ + last_used_port = rover; + return 0; } - ret = -EADDRNOTAVAIL; - goto err2; - } - - if (port == high) - next_port = low; - else - next_port = port + 1; - - bind_list->ps = ps; - bind_list->port = (unsigned short) port; - cma_bind_port(bind_list, id_priv); - return 0; -err2: - idr_remove(ps, port); -err1: - kfree(bind_list); - return ret; + } while (--remaining > 0); + return -EADDRNOTAVAIL; } static int cma_use_port(struct idr *ps, struct rdma_id_private *id_priv) @@ -2995,12 +2978,7 @@ static void cma_remove_one(struct ib_dev static int __init cma_init(void) { - int ret, low, high, remaining; - - get_random_bytes(&next_port, sizeof next_port); - inet_get_local_port_range(&low, &high); - remaining = (high - low) + 1; - next_port = ((unsigned int) next_port % remaining) + low; + int ret; cma_wq = create_singlethread_workqueue("rdma_cm"); if (!cma_wq)
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