Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754630Ab0DMBWd (ORCPT ); Mon, 12 Apr 2010 21:22:33 -0400 Received: from www262.sakura.ne.jp ([202.181.97.72]:62419 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754481Ab0DMBWb (ORCPT ); Mon, 12 Apr 2010 21:22:31 -0400 Message-Id: <201004130121.o3D1Lhh7099571@www262.sakura.ne.jp> Subject: Re: [Patch 3/3] net: reserve ports for applications using fixed port numbers From: Tetsuo Handa To: amwang@redhat.com Cc: opurdila@ixiacom.com, eric.dumazet@gmail.com, netdev@vger.kernel.org, nhorman@tuxdriver.com, davem@davemloft.net, ebiederm@xmission.com, linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Date: Tue, 13 Apr 2010 10:21:43 +0900 References: <20100412100744.5302.92442.sendpatchset@localhost.localdomain> <20100412100816.5302.74919.sendpatchset@localhost.localdomain> In-Reply-To: <20100412100816.5302.74919.sendpatchset@localhost.localdomain> Content-Type: text/plain; charset="ISO-2022-JP" X-Anti-Virus: K-Prox Anti-Virus Powered by Kaspersky, bases: 12042010 #3702773, status: clean Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2816 Lines: 99 Hello. > --- 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 (!ret && inet_is_reserved_local_port(port)) > + ret = -EAGAIN; > } while ((ret == -EAGAIN) && idr_pre_get(ps, GFP_KERNEL)); > > if (ret) > I think above part is wrong. Below program -------------------- #include #include #include static DEFINE_IDR(idr); static int idr_demo_init(void) { int next_port = 65530; int port = 0; int ret = -EINTR; while (!signal_pending(current)) { msleep(1000); ret = idr_get_new_above(&idr, NULL, next_port, &port); printk(KERN_INFO "idr_get_new_above() = %d\n", ret); if (!ret) { /* Emulate inet_is_reserved_local_port(port) = true */ printk(KERN_INFO "Port %u is reserved.\n", port); ret = -EAGAIN; } if (ret == -EAGAIN) { if (idr_pre_get(&idr, GFP_KERNEL)) { printk(KERN_INFO "idr_pre_get() succeeded.\n"); continue; } printk(KERN_INFO "idr_pre_get() failed.\n"); break; } else { printk(KERN_INFO "next_port=%u port=%u\n", next_port, port); break; } } if (!ret) idr_remove(&idr, port); idr_destroy(&idr); return -EINVAL; } module_init(idr_demo_init); MODULE_LICENSE("GPL"); -------------------- generated below output. idr_get_new_above() = -11 idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65530 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65531 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65532 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65533 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65534 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65535 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65536 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 Port 65537 is reserved. idr_pre_get() succeeded. idr_get_new_above() = 0 (...snipped...) This result suggests that above loop will continue until idr_pre_get() fails due to out of memory if all ports were reserved. Also, if idr_get_new_above() returned 0, bind_list (which is a kmalloc()ed pointer) is already installed into a free slot (see comment on idr_get_new_above_int()). Thus, simply calling idr_get_new_above() again will install the same pointer into multiple slots. I guess it will malfunction later. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/