Messages in this thread | | | From | "Sean Hefty" <> | Subject | RE: [PATCH] Infiniband: Randomize local port allocation. | Date | Wed, 14 Apr 2010 17:01:04 -0700 |
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>[PATCH] Infiniband: Randomize local port allocation. > >Randomize local port allocation in a way sctp_get_port_local() does. > >Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Thanks for fixing this long outstanding issue. :) The latest patch looks correct and passed some simple tests that I ran against it. One comment below, which I didn't catch before:
>--- > drivers/infiniband/core/cma.c | 69 ++++++++++++++--------------------------- >- > 1 file changed, 24 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 +1969,32 @@ 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;
Assuming that we're likely to pick a valid port on the first try, it would be more efficient to move the above 3 lines to the end of the while loop.
>+ if (last_used_port != rover && >+ !idr_find(ps, (unsigned short) rover)) { >+ int ret = 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. >+ */ >+ if (!ret) >+ last_used_port = rover; >+ if (ret != -EADDRNOTAVAIL) >+ return ret; > } >- 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; > }
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