5c346525d3
Xiaolong reported a suspicious rcu_dereference_check in the device
unregister notifier callback. Since we do not dereference the
rx_handler_data, it's ok to just check for the value of the pointer.
Note that this section is already protected by rtnl_lock.
[ 101.364846] WARNING: suspicious RCU usage
[ 101.365654] 4.13.0-rc6-01701-gceed73a #1 Not tainted
[ 101.370873] -----------------------------
[ 101.372472] drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c:57 suspicious rcu_dereference_check() usage!
[ 101.374427]
[ 101.374427] other info that might help us debug this:
[ 101.374427]
[ 101.387491]
[ 101.387491] rcu_scheduler_active = 2, debug_locks = 1
[ 101.389368] 1 lock held by trinity-main/2809:
[ 101.390736] #0: (rtnl_mutex){+.+.+.}, at: [<8146085b>] rtnl_lock+0xf/0x11
[ 101.395482]
[ 101.395482] stack backtrace:
[ 101.396948] CPU: 0 PID: 2809 Comm: trinity-main Not tainted 4.13.0-rc6-01701-gceed73a #1
[ 101.398857] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.9.3-20161025_171302-gandalf 04/01/2014
[ 101.401079] Call Trace:
[ 101.401656] dump_stack+0xa1/0xeb
[ 101.402871] lockdep_rcu_suspicious+0xc7/0xd0
[ 101.403665] rmnet_is_real_dev_registered+0x40/0x4e
[ 101.405199] rmnet_config_notify_cb+0x2c/0x142
[ 101.406344] ? wireless_nlevent_flush+0x47/0x71
[ 101.407385] notifier_call_chain+0x2d/0x47
[ 101.408645] raw_notifier_call_chain+0xc/0xe
[ 101.409882] call_netdevice_notifiers_info+0x41/0x49
[ 101.411402] call_netdevice_notifiers+0xc/0xe
[ 101.412713] rollback_registered_many+0x268/0x36e
[ 101.413702] rollback_registered+0x39/0x56
[ 101.414965] unregister_netdevice_queue+0x79/0x88
[ 101.415908] unregister_netdev+0x16/0x1d
Fixes: ceed73a2cf ("drivers: net: ethernet: qualcomm: rmnet: Initial implementation")
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Reported-by: kernel test robot <xiaolong.ye@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.