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IB/hfi1: Protect the interval RB tree when cleaning up

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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 <dean.luick@intel.com>
Signed-off-by: Mitko Haralanov <mitko.haralanov@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>
This commit is contained in:
Mitko Haralanov
2016-04-12 10:46:35 -07:00
committed by Doug Ledford
parent 0ad2d3d05b
commit 782f6697d2
1 changed files with 6 additions and 2 deletions
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8
drivers/staging/rdma/hfi1/mmu_rb.c
View File

@@ -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);
}