Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Mon, 12 Apr 2010 14:52:59 +0800 | From | Cong Wang <> | Subject | Re: [Patch 3/3] net: reserve ports for applications using fixed port numbers |
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Tetsuo Handa wrote: > 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.
Hmm, good catch! I think it is correct.
> >> } 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). >
Yeah, how about:
int tries = 10; ... again: ... if (inet_is_reserved_local_port(next_port)) { if (tries--) goto again; else return -EBUSY; }
?
>> 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.
Sorry, doesn't 'continue' jump to exactly where 'next_nolock' is?? Or I am missing something?
Thanks for your review!
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