Messages in this thread | | | Subject | Re: [Patch 3/3] net: reserve ports for applications using fixed port numbers | From | Tetsuo Handa <> | Date | Tue, 13 Apr 2010 10:21:43 +0900 |
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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 <linux/module.h> #include <linux/sched.h> #include <linux/idr.h>
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.
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