Commit 187229c2 authored May 23, 2019 by Jason Gunthorpe

mm/hmm: Remove racy protection against double-unregistration



No other register/unregister kernel API attempts to provide this kind of
protection as it is inherently racy, so just drop it.

Callers should provide their own protection, and it appears nouveau
already does.

Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Jérôme Glisse <jglisse@redhat.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Tested-by: Philip Yang <Philip.Yang@amd.com>

parent 8a1a0cd0

mm/hmm.c

+1 −7

Original line number	Diff line number	Diff line
		@@ -276,17 +276,11 @@ EXPORT_SYMBOL(hmm_mirror_register);
		*/
		void hmm_mirror_unregister(struct hmm_mirror *mirror)
		{
		struct hmm *hmm = READ_ONCE(mirror->hmm);

		if (hmm == NULL)
		return;
		struct hmm *hmm = mirror->hmm;

		down_write(&hmm->mirrors_sem);
		list_del_init(&mirror->list);
		/* To protect us against double unregister ... */
		mirror->hmm = NULL;
		up_write(&hmm->mirrors_sem);

		hmm_put(hmm);
		}
		EXPORT_SYMBOL(hmm_mirror_unregister);

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