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Date: Fri, 9 Apr 2010 22:21:50 +0900 From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp> To: amwang@...hat.com, linux-kernel@...r.kernel.org Cc: opurdila@...acom.com, eric.dumazet@...il.com, netdev@...r.kernel.org, nhorman@...driver.com, davem@...emloft.net, ebiederm@...ssion.com Subject: Re: [Patch 3/3] net: reserve ports for applications using fixed port numbers 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 netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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