From: Jason Gunthorpe <[email protected]> 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, it appears nouveau already does, but just in case drop a debugging POISON. Signed-off-by: Jason Gunthorpe <[email protected]> Reviewed-by: Jérôme Glisse <[email protected]> Reviewed-by: John Hubbard <[email protected]> Reviewed-by: Ralph Campbell <[email protected]> Tested-by: Philip Yang <[email protected]> --- mm/hmm.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/mm/hmm.c b/mm/hmm.c index c0f622f86223c2..e3e0a811a3a774 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -283,18 +283,13 @@ 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); + memset(&mirror->hmm, POISON_INUSE, sizeof(mirror->hmm)); } EXPORT_SYMBOL(hmm_mirror_unregister); -- 2.21.0 _______________________________________________ dri-devel mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/dri-devel
