From 782f6697d20d180843565ac93726f5ec6c7ec8ce Mon Sep 17 00:00:00 2001 From: Mitko Haralanov Date: Tue, 12 Apr 2016 10:46:35 -0700 Subject: [PATCH] IB/hfi1: Protect the interval RB tree when cleaning up The current implementation of the clean up function for the interval RB trees has two flaws which may cause problems in cases of concurrent executing of the function and MMU notifier. The flaws were due to the fact that deregistration of the MMU callbacks was done after the tree was emptied and, furthermore, the tree was not being locked. This commit fixes both of these flaws by, first, switch the order of operations, and, second, locking the tree while traversing it to prevent any other operations. Reviewed-by: Dean Luick Signed-off-by: Mitko Haralanov Signed-off-by: Doug Ledford --- drivers/staging/rdma/hfi1/mmu_rb.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/staging/rdma/hfi1/mmu_rb.c b/drivers/staging/rdma/hfi1/mmu_rb.c index b3f0682a36c9..72b6d70ae2b5 100644 --- a/drivers/staging/rdma/hfi1/mmu_rb.c +++ b/drivers/staging/rdma/hfi1/mmu_rb.c @@ -126,10 +126,15 @@ void hfi1_mmu_rb_unregister(struct rb_root *root) if (!handler) return; + /* Unregister first so we don't get any more notifications. */ + if (current->mm) + mmu_notifier_unregister(&handler->mn, current->mm); + spin_lock_irqsave(&mmu_rb_lock, flags); list_del(&handler->list); spin_unlock_irqrestore(&mmu_rb_lock, flags); + spin_lock_irqsave(&handler->lock, flags); if (!RB_EMPTY_ROOT(root)) { struct rb_node *node; struct mmu_rb_node *rbnode; @@ -141,9 +146,8 @@ void hfi1_mmu_rb_unregister(struct rb_root *root) handler->ops->remove(root, rbnode, NULL); } } + spin_unlock_irqrestore(&handler->lock, flags); - if (current->mm) - mmu_notifier_unregister(&handler->mn, current->mm); kfree(handler); } -- 2.20.1