From: Bjørn Mork bjorn@mork.no
[ Upstream commit 6c730080e663b1d629f8aa89348291fbcdc46cd9 ]
The notifier calls were thrown in as a last-minute fix for an imagined "this device could be part of a bridge" problem. That revealed a certain lack of locking. Not to mention testing...
Avoid this splat:
RTNL: assertion failed at net/core/dev.c (1639) CPU: 0 PID: 4293 Comm: bash Not tainted 4.4.0-rc3+ #358 Hardware name: LENOVO 2776LEG/2776LEG, BIOS 6EET55WW (3.15 ) 12/19/2011 0000000000000000 ffff8800ad253d60 ffffffff8122f7cf ffff8800ad253d98 ffff8800ad253d88 ffffffff813833ab 0000000000000002 ffff880230f48560 ffff880230a12900 ffff8800ad253da0 ffffffff813833da 0000000000000002 Call Trace: [<ffffffff8122f7cf>] dump_stack+0x4b/0x63 [<ffffffff813833ab>] call_netdevice_notifiers_info+0x3d/0x59 [<ffffffff813833da>] call_netdevice_notifiers+0x13/0x15 [<ffffffffa09be227>] raw_ip_store+0x81/0x193 [qmi_wwan] [<ffffffff8131e149>] dev_attr_store+0x20/0x22 [<ffffffff811d858b>] sysfs_kf_write+0x49/0x50 [<ffffffff811d8027>] kernfs_fop_write+0x10a/0x151 [<ffffffff8117249a>] __vfs_write+0x26/0xa5 [<ffffffff81085ed4>] ? percpu_down_read+0x53/0x7f [<ffffffff81174c9e>] ? __sb_start_write+0x5f/0xb0 [<ffffffff81174c9e>] ? __sb_start_write+0x5f/0xb0 [<ffffffff81172c37>] vfs_write+0xa3/0xe7 [<ffffffff811734ad>] SyS_write+0x50/0x7e [<ffffffff8145c517>] entry_SYSCALL_64_fastpath+0x12/0x6f
Fixes: 32f7adf633b9 ("net: qmi_wwan: support "raw IP" mode") Signed-off-by: Bjørn Mork bjorn@mork.no Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/usb/qmi_wwan.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-)
diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c index d6ecb3ac25b6c..e75e984483bc5 100644 --- a/drivers/net/usb/qmi_wwan.c +++ b/drivers/net/usb/qmi_wwan.c @@ -16,6 +16,7 @@ #include <linux/etherdevice.h> #include <linux/if_arp.h> #include <linux/mii.h> +#include <linux/rtnetlink.h> #include <linux/usb.h> #include <linux/usb/cdc.h> #include <linux/usb/usbnet.h> @@ -92,7 +93,7 @@ static ssize_t raw_ip_store(struct device *d, struct device_attribute *attr, co struct usbnet *dev = netdev_priv(to_net_dev(d)); struct qmi_wwan_state *info = (void *)&dev->data; bool enable; - int err; + int ret;
if (strtobool(buf, &enable)) return -EINVAL; @@ -101,18 +102,22 @@ static ssize_t raw_ip_store(struct device *d, struct device_attribute *attr, co if (enable == (info->flags & QMI_WWAN_FLAG_RAWIP)) return len;
+ if (!rtnl_trylock()) + return restart_syscall(); + /* we don't want to modify a running netdev */ if (netif_running(dev->net)) { netdev_err(dev->net, "Cannot change a running device\n"); - return -EBUSY; + ret = -EBUSY; + goto err; }
/* let other drivers deny the change */ - err = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev->net); - err = notifier_to_errno(err); - if (err) { + ret = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev->net); + ret = notifier_to_errno(ret); + if (ret) { netdev_err(dev->net, "Type change was refused\n"); - return err; + goto err; }
if (enable) @@ -121,7 +126,10 @@ static ssize_t raw_ip_store(struct device *d, struct device_attribute *attr, co info->flags &= ~QMI_WWAN_FLAG_RAWIP; qmi_wwan_netdev_setup(dev->net); call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev->net); - return len; + ret = len; +err: + rtnl_unlock(); + return ret; }
static DEVICE_ATTR_RW(raw_ip);