git.openwrt.org Git - openwrt/staging/hauke.git/blob

   1 From 6c730080e663b1d629f8aa89348291fbcdc46cd9 Mon Sep 17 00:00:00 2001
   2 From: =?UTF-8?q?Bj=C3=B8rn=20Mork?= <bjorn@mork.no>
   3 Date: Sun, 6 Dec 2015 21:25:50 +0100
   4 Subject: [PATCH] net: qmi_wwan: should hold RTNL while changing netdev type
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 The notifier calls were thrown in as a last-minute fix for an
  10 imagined "this device could be part of a bridge" problem. That
  11 revealed a certain lack of locking.  Not to mention testing...
  12
  13 Avoid this splat:
  14
  15 RTNL: assertion failed at net/core/dev.c (1639)
  16 CPU: 0 PID: 4293 Comm: bash Not tainted 4.4.0-rc3+ #358
  17 Hardware name: LENOVO 2776LEG/2776LEG, BIOS 6EET55WW (3.15 ) 12/19/2011
  18  0000000000000000 ffff8800ad253d60 ffffffff8122f7cf ffff8800ad253d98
  19  ffff8800ad253d88 ffffffff813833ab 0000000000000002 ffff880230f48560
  20  ffff880230a12900 ffff8800ad253da0 ffffffff813833da 0000000000000002
  21 Call Trace:
  22  [<ffffffff8122f7cf>] dump_stack+0x4b/0x63
  23  [<ffffffff813833ab>] call_netdevice_notifiers_info+0x3d/0x59
  24  [<ffffffff813833da>] call_netdevice_notifiers+0x13/0x15
  25  [<ffffffffa09be227>] raw_ip_store+0x81/0x193 [qmi_wwan]
  26  [<ffffffff8131e149>] dev_attr_store+0x20/0x22
  27  [<ffffffff811d858b>] sysfs_kf_write+0x49/0x50
  28  [<ffffffff811d8027>] kernfs_fop_write+0x10a/0x151
  29  [<ffffffff8117249a>] __vfs_write+0x26/0xa5
  30  [<ffffffff81085ed4>] ? percpu_down_read+0x53/0x7f
  31  [<ffffffff81174c9e>] ? __sb_start_write+0x5f/0xb0
  32  [<ffffffff81174c9e>] ? __sb_start_write+0x5f/0xb0
  33  [<ffffffff81172c37>] vfs_write+0xa3/0xe7
  34  [<ffffffff811734ad>] SyS_write+0x50/0x7e
  35  [<ffffffff8145c517>] entry_SYSCALL_64_fastpath+0x12/0x6f
  36
  37 Fixes: 32f7adf633b9 ("net: qmi_wwan: support "raw IP" mode")
  38 Signed-off-by: Bjørn Mork <bjorn@mork.no>
  39 Signed-off-by: David S. Miller <davem@davemloft.net>
  40 ---
  41  drivers/net/usb/qmi_wwan.c | 22 +++++++++++++++-------
  42  1 file changed, 15 insertions(+), 7 deletions(-)
  43
  44 diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c
  45 index 98add3bf8821..babc84a3946c 100644
  46 --- a/drivers/net/usb/qmi_wwan.c
  47 +++ b/drivers/net/usb/qmi_wwan.c
  48 @@ -16,6 +16,7 @@
  49  #include <linux/etherdevice.h>
  50  #include <linux/if_arp.h>
  51  #include <linux/mii.h>
  52 +#include <linux/rtnetlink.h>
  53  #include <linux/usb.h>
  54  #include <linux/usb/cdc.h>
  55  #include <linux/usb/usbnet.h>
  56 @@ -92,7 +93,7 @@ static ssize_t raw_ip_store(struct device *d,  struct device_attribute *attr, co
  57         struct usbnet *dev = netdev_priv(to_net_dev(d));
  58         struct qmi_wwan_state *info = (void *)&dev->data;
  59         bool enable;
  60 -       int err;
  61 +       int ret;
  62
  63         if (strtobool(buf, &enable))
  64                 return -EINVAL;
  65 @@ -101,18 +102,22 @@ static ssize_t raw_ip_store(struct device *d,  struct device_attribute *attr, co
  66         if (enable == (info->flags & QMI_WWAN_FLAG_RAWIP))
  67                 return len;
  68
  69 +       if (!rtnl_trylock())
  70 +               return restart_syscall();
  71 +
  72         /* we don't want to modify a running netdev */
  73         if (netif_running(dev->net)) {
  74                 netdev_err(dev->net, "Cannot change a running device\n");
  75 -               return -EBUSY;
  76 +               ret = -EBUSY;
  77 +               goto err;
  78         }
  79
  80         /* let other drivers deny the change */
  81 -       err = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev->net);
  82 -       err = notifier_to_errno(err);
  83 -       if (err) {
  84 +       ret = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev->net);
  85 +       ret = notifier_to_errno(ret);
  86 +       if (ret) {
  87                 netdev_err(dev->net, "Type change was refused\n");
  88 -               return err;
  89 +               goto err;
  90         }
  91
  92         if (enable)
  93 @@ -121,7 +126,10 @@ static ssize_t raw_ip_store(struct device *d,  struct device_attribute *attr, co
  94                 info->flags &= ~QMI_WWAN_FLAG_RAWIP;
  95         qmi_wwan_netdev_setup(dev->net);
  96         call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev->net);
  97 -       return len;
  98 +       ret = len;
  99 +err:
 100 +       rtnl_unlock();
 101 +       return ret;
 102  }
 103
 104  static DEVICE_ATTR_RW(raw_ip);
 105 --
 106 2.7.4
 107