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Subject[PATCH] rdma/cm: Randomize local port allocation.
Date
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

>Randomize local port allocation in a way sctp_get_port_local() does.
>Update rover at the end of loop since we're likely to pick a valid port
>on the first try.
>
>Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Sean Hefty <sean.hefty@intel.com>

>---

I like this version, thanks! I'm not sure which tree to merge it through.
Are you needing this for 2.6.34, or is 2.6.35 okay?

> drivers/infiniband/core/cma.c | 70 +++++++++++++++--------------------------
>-
> 1 file changed, 25 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 +1969,33 @@ 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;
>- }
>- ret = -EADDRNOTAVAIL;
>- goto err2;
>+ remaining = (high - low) + 1;
>+ rover = net_random() % remaining + low;
>+retry:
>+ 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;
> }
>-
>- 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;
>+ if (--remaining) {
>+ rover++;
>+ if ((rover < low) || (rover > high))
>+ rover = low;
>+ goto retry;
>+ }
>+ return -EADDRNOTAVAIL;
> }
>
> static int cma_use_port(struct idr *ps, struct rdma_id_private *id_priv)
>@@ -2995,12 +2980,7 @@ 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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