Erez Shitrit ab43aaa00d IB/ipoib: Fix race condition in neigh creation ... [ Upstream commit 16ba3defb8 ] When using enhanced mode for IPoIB, two threads may execute xmit in parallel to two different TX queues while the target is the same. In this case, both of them will add the same neighbor to the path's neigh link list and we might see the following message: list_add double add: new=ffff88024767a348, prev=ffff88024767a348... WARNING: lib/list_debug.c:31__list_add_valid+0x4e/0x70 ipoib_start_xmit+0x477/0x680 [ib_ipoib] dev_hard_start_xmit+0xb9/0x3e0 sch_direct_xmit+0xf9/0x250 __qdisc_run+0x176/0x5d0 __dev_queue_xmit+0x1f5/0xb10 __dev_queue_xmit+0x55/0xb10 Analysis: Two SKB are scheduled to be transmitted from two cores. In ipoib_start_xmit, both gets NULL when calling ipoib_neigh_get. Two calls to neigh_add_path are made. One thread takes the spin-lock and calls ipoib_neigh_alloc which creates the neigh structure, then (after the __path_find) the neigh is added to the path's neigh link list. When the second thread enters the critical section it also calls ipoib_neigh_alloc but in this case it gets the already allocated ipoib_neigh structure, which is already linked to the path's neigh link list and adds it again to the list. Which beside of triggering the list, it creates a loop in the linked list. This loop leads to endless loop inside path_rec_completion. Solution: Check list_empty(&neigh->list) before adding to the list. Add a similar fix in "ipoib_multicast.c::ipoib_mcast_send" Fixes: b63b70d877 ('IPoIB: Use a private hash table for path lookup in xmit path') 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: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2018-03-03 10:23:25 +01:00
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core	IB/core: disable memory registration of filesystem-dax vmas	2018-02-28 10:18:34 +01:00
hw	IB/mlx4: Fix mlx4_ib_alloc_mr error flow	2018-03-03 10:23:25 +01:00
sw	RDMA/rxe: Fix a race condition related to the QP error state	2018-02-22 15:43:52 +01:00
ulp	IB/ipoib: Fix race condition in neigh creation	2018-03-03 10:23:25 +01:00
Kconfig	qedr: Add RoCE driver framework	2016-10-14 15:00:10 -04:00
Makefile	IB/rdmavt: Create module framework and handle driver registration	2016-03-10 20:37:04 -05:00