Francesco Ruggeri 024a8168b7 igb: reinit_locked() should be called with rtnl_lock
We observed two panics involving races with igb_reset_task.
The first panic is caused by this race condition:

	kworker			reboot -f

	igb_reset_task
	igb_reinit_locked
	igb_down
	napi_synchronize
				__igb_shutdown
				igb_clear_interrupt_scheme
				igb_free_q_vectors
				igb_free_q_vector
				adapter->q_vector[v_idx] = NULL;
	napi_disable
	Panics trying to access
	adapter->q_vector[v_idx].napi_state

The second panic (a divide error) is caused by this race:

kworker		reboot -f	tx packet

igb_reset_task
		__igb_shutdown
		rtnl_lock()
		...
		igb_clear_interrupt_scheme
		igb_free_q_vectors
		adapter->num_tx_queues = 0
		...
		rtnl_unlock()
rtnl_lock()
igb_reinit_locked
igb_down
igb_up
netif_tx_start_all_queues
				dev_hard_start_xmit
				igb_xmit_frame
				igb_tx_queue_mapping
				Panics on
				r_idx % adapter->num_tx_queues

This commit applies to igb_reset_task the same changes that
were applied to ixgbe in commit 2f90b8657ec9 ("ixgbe: this patch
adds support for DCB to the kernel and ixgbe driver"),
commit 8f4c5c9fb87a ("ixgbe: reinit_locked() should be called with
rtnl_lock") and commit 88adce4ea8f9 ("ixgbe: fix possible race in
reset subtask").

Signed-off-by: Francesco Ruggeri <fruggeri@arista.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
2020-07-30 10:05:14 -07:00
2020-07-25 14:42:11 -07:00
2020-07-10 09:55:46 -07:00
2020-07-25 13:18:42 -07:00
2020-07-21 08:06:45 -07:00
2020-07-24 12:42:41 -07:00
2020-07-19 15:41:18 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

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.
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