net: reserve ports for applications using fixed port numbers
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From: Tetsuo Handa on 9 Apr 2010 09:30 Hello. Amerigo Wang wrote: > Index: linux-2.6/drivers/infiniband/core/cma.c > =================================================================== > --- 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 (inet_is_reserved_local_port(port)) > + ret = -EAGAIN; You should not overwrite ret with -EAGAIN when idr_get_new_above() returned -ENOSPC. I don't know about idr, thus I don't know whether if (!ret && inet_is_reserved_local_port(port)) ret = -EAGAIN; is correct or not. > } while ((ret == -EAGAIN) && idr_pre_get(ps, GFP_KERNEL)); > > if (ret) > @@ -2996,10 +2998,13 @@ 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); > +again: > + get_random_bytes(&next_port, sizeof next_port); > remaining = (high - low) + 1; > next_port = ((unsigned int) next_port % remaining) + low; > + if (inet_is_reserved_local_port(next_port)) > + goto again; > You should not unconditionally "goto again;". If all ports were reserved, it will loop forever (CPU stalls). > cma_wq = create_singlethread_workqueue("rdma_cm"); > if (!cma_wq) > Index: linux-2.6/net/sctp/socket.c > =================================================================== > --- linux-2.6.orig/net/sctp/socket.c > +++ linux-2.6/net/sctp/socket.c > @@ -5436,6 +5436,8 @@ static long sctp_get_port_local(struct s > rover++; > if ((rover < low) || (rover > high)) > rover = low; > + if (inet_is_reserved_local_port(rover)) > + continue; This one needs to be if (inet_is_reserved_local_port(rover)) goto next_nolock; > index = sctp_phashfn(rover); > head = &sctp_port_hashtable[index]; > sctp_spin_lock(&head->lock); next: sctp_spin_unlock(&head->lock); +next_nolock: } while (--remaining > 0); otherwise, it will loop forever if all ports were reserved. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Tetsuo Handa on 12 Apr 2010 03:10 Cong Wang wrote: > Tetsuo Handa wrote: > >> Index: linux-2.6/net/sctp/socket.c > >> =================================================================== > >> --- linux-2.6.orig/net/sctp/socket.c > >> +++ linux-2.6/net/sctp/socket.c > >> @@ -5436,6 +5436,8 @@ static long sctp_get_port_local(struct s > >> rover++; > >> if ((rover < low) || (rover > high)) > >> rover = low; > >> + if (inet_is_reserved_local_port(rover)) > >> + continue; > > > > This one needs to be > > > > if (inet_is_reserved_local_port(rover)) > > goto next_nolock; > > > >> index = sctp_phashfn(rover); > >> head = &sctp_port_hashtable[index]; > >> sctp_spin_lock(&head->lock); > > > > next: > > sctp_spin_unlock(&head->lock); > > +next_nolock: > > } while (--remaining > 0); > > > > otherwise, it will loop forever if all ports were reserved. > > Sorry, doesn't 'continue' jump to exactly where 'next_nolock' is?? > Or I am missing something? My misreading, sorry. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Tetsuo Handa on 12 Apr 2010 21:30 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 -------------------- #include <linux/module.h> #include <linux/sched.h> #include <linux/idr.h> static DEFINE_IDR(idr); static int idr_demo_init(void) { int next_port = 65530; int port = 0; int ret = -EINTR; while (!signal_pending(current)) { msleep(1000); ret = idr_get_new_above(&idr, NULL, next_port, &port); printk(KERN_INFO "idr_get_new_above() = %d\n", ret); if (!ret) { /* Emulate inet_is_reserved_local_port(port) = true */ printk(KERN_INFO "Port %u is reserved.\n", port); ret = -EAGAIN; } if (ret == -EAGAIN) { if (idr_pre_get(&idr, GFP_KERNEL)) { printk(KERN_INFO "idr_pre_get() succeeded.\n"); continue; } printk(KERN_INFO "idr_pre_get() failed.\n"); break; } else { printk(KERN_INFO "next_port=%u port=%u\n", next_port, port); break; } } if (!ret) idr_remove(&idr, port); idr_destroy(&idr); return -EINVAL; } module_init(idr_demo_init); MODULE_LICENSE("GPL"); -------------------- generated below output. idr_get_new_above() = -11 idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65530 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65531 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65532 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65533 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65534 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65535 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65536 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65537 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 (...snipped...) 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Tetsuo Handa on 13 Apr 2010 09:20 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) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Sean Hefty on 13 Apr 2010 12:40
>Sean and Roland, is below patch correct? >inet_is_reserved_local_port() is the new function proposed in this patchset. It looks correct to me. I didn't test the patch series, but if I comment out the call to inet_is_reserved_local_port() in the provided below, the changes worked fine for me. Acked-by: Sean Hefty <sean.hefty(a)intel.com> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |