From ca748c39ea3f3c755295d64d69ba0b4375e34b5d Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Sun, 16 Sep 2018 20:48:09 +0300 Subject: RDMA/umem: Get rid of per_mm->notifier_count This is intrinsically racy and the scheme is simply unnecessary. New MR registration can wait for any on going invalidation to fully complete. CPU0 CPU1 if (atomic_read()) if (atomic_dec_and_test() && !list_empty()) { /* not taken */ } list_add() Putting the new UMEM into some kind of purgatory until another invalidate rolls through.. Instead hold the read side of the umem_rwsem across the pair'd start/end and get rid of the racy 'deferred add' approach. Since all umem's in the rbt are always ready to go, also get rid of the mn_counters_active stuff. Signed-off-by: Jason Gunthorpe Signed-off-by: Leon Romanovsky Signed-off-by: Doug Ledford --- include/rdma/ib_umem_odp.h | 15 --------------- 1 file changed, 15 deletions(-) (limited to 'include/rdma/ib_umem_odp.h') diff --git a/include/rdma/ib_umem_odp.h b/include/rdma/ib_umem_odp.h index 259eb08dfc9e..ce9502545903 100644 --- a/include/rdma/ib_umem_odp.h +++ b/include/rdma/ib_umem_odp.h @@ -67,15 +67,9 @@ struct ib_umem_odp { struct mutex umem_mutex; void *private; /* for the HW driver to use. */ - /* When false, use the notifier counter in the ucontext struct. */ - bool mn_counters_active; int notifiers_seq; int notifiers_count; - /* A linked list of umems that don't have private mmu notifier - * counters yet. */ - struct list_head no_private_counters; - /* Tree tracking */ struct umem_odp_node interval_tree; @@ -99,11 +93,8 @@ struct ib_ucontext_per_mm { struct rb_root_cached umem_tree; /* Protects umem_tree */ struct rw_semaphore umem_rwsem; - atomic_t notifier_count; struct mmu_notifier mn; - /* A list of umems that don't have private mmu notifier counters yet. */ - struct list_head no_private_counters; unsigned int odp_mrs_count; struct list_head ucontext_list; @@ -162,12 +153,6 @@ static inline int ib_umem_mmu_notifier_retry(struct ib_umem_odp *umem_odp, * and the ucontext umem_mutex semaphore locked for read). */ - /* Do not allow page faults while the new ib_umem hasn't seen a state - * with zero notifiers yet, and doesn't have its own valid set of - * private counters. */ - if (!umem_odp->mn_counters_active) - return 1; - if (unlikely(umem_odp->notifiers_count)) return 1; if (umem_odp->notifiers_seq != mmu_seq) -- cgit v1.2.3