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In order to avoid deadlock between sysfs functions (like create/delete child) and remove_one (both of them are using the sysfs lock and rtnl_lock) the driver will use a state mutex for sync. That will fix traces as the following: schedule+0x3e/0x90 kernfs_drain+0x75/0xf0 ? wait_woken+0x90/0x90 __kernfs_remove+0x12e/0x1c0 kernfs_remove+0x25/0x40 sysfs_remove_dir+0x57/0x90 kobject_del+0x22/0x60 device_del+0x195/0x230 pm_runtime_set_memalloc_noio+0xac/0xf0 netdev_unregister_kobject+0x71/0x80 rollback_registered_many+0x205/0x2f0 rollback_registered+0x31/0x40 unregister_netdevice_queue+0x58/0xb0 unregister_netdev+0x20/0x30 ipoib_remove_one+0xb7/0x240 [ib_ipoib] ib_unregister_device+0xbc/0x1b0 [ib_core] ib_unregister_mad_agent+0x29/0x30 [ib_core] mlx4_ib_remove+0x67/0x280 [mlx4_ib] INFO: task echo:24082 blocked for more than 120 seconds. Tainted: G OE 4.1.12-37.5.1.el6uek.x86_64 #2 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. Call Trace: schedule+0x3e/0x90 schedule_preempt_disabled+0xe/0x10 __mutex_lock_slowpath+0x95/0x110 ? _rcu_barrier+0x177/0x220 mutex_lock+0x23/0x40 rtnl_lock+0x15/0x20 netdev_run_todo+0x81/0x1f0 rtnl_unlock+0xe/0x10 ipoib_vlan_delete+0x12f/0x1c0 [ib_ipoib] delete_child+0x69/0x80 [ib_ipoib] dev_attr_store+0x20/0x30 sysfs_kf_write+0x41/0x50 Signed-off-by: Erez Shitrit <erezsh@mellanox.com> Reviewed-by: Alex Vesker <valex@mellanox.com> Signed-off-by: Leon Romanovsky <leon@kernel.org> Signed-off-by: Doug Ledford <dledford@redhat.com>
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.