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Jason Gunthorpe authored
This fixes a race of the form: CPU0 CPU1 mlx5_ib_invalidate_range() mlx5_ib_invalidate_range() // This one actually makes npages == 0 ib_umem_odp_unmap_dma_pages() if (npages == 0 && !dying) // This one does nothing ib_umem_odp_unmap_dma_pages() if (npages == 0 && !dying) dying = 1; dying = 1; schedule_work(&umem_odp->work); // Double schedule of the same work schedule_work(&umem_odp->work); // BOOM npages and dying must be read and written under the umem_mutex lock. Since whenever ib_umem_odp_unmap_dma_pages() is called mlx5 must also call mlx5_ib_update_xlt, and both need to be done in the same locking region, hoist the lock out of unmap. This avoids an expensive double critical section in mlx5_ib_invalidate_range(). Fixes: 81713d37 ("IB/mlx5: Add implicit MR support") Link: https://lore.kernel.org/r/20191001153821.23621-4-jgg@ziepe.caReviewed-by: Artemy Kovalyov <artemyko@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
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