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Message-Id: <201004150546.o3F5kUtb094163@www262.sakura.ne.jp>
Date: Thu, 15 Apr 2010 14:46:30 +0900
From: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To: sean.hefty@...el.com
Cc: netdev@...r.kernel.org, rolandd@...co.com, amwang@...hat.com
Subject: RE: [PATCH] Infiniband: Randomize local port allocation.
Tetsuo Handa wrote:
> Sean Hefty wrote:
> > >+ 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.
> >
> Indeed. I moved these lines to "if (--remaining) { ... }" block.
Oh, I made more changes than needed.
Adding "goto start;" and "start:" are sufficient.
Please use whichever you like.
--------------------
[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@...ove.SAKURA.ne.jp>
---
drivers/infiniband/core/cma.c | 71 +++++++++++++++---------------------------
1 file changed, 26 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 +1969,34 @@ 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;
+ goto start;
+ do {
+ rover++;
+ if ((rover < low) || (rover > high))
+ rover = low;
+start:
+ 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);
+ return -EADDRNOTAVAIL;
}
static int cma_use_port(struct idr *ps, struct rdma_id_private *id_priv)
@@ -2995,12 +2981,7 @@ 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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