From f53af85e4735514a572996fb551968da78657639 Mon Sep 17 00:00:00 2001 From: Mitko Haralanov Date: Tue, 12 Apr 2016 10:46:47 -0700 Subject: [PATCH] IB/hfi1: Extract and reinsert MMU RB node on lookup The page pinning function, which also maintains the pin cache, behaves one of two ways when an exact buffer match is not found: 1. If no node is not found (a buffer with the same starting address is not found in the cache), a new node is created, the buffer pages are pinned, and the node is inserted into the RB tree, or 2. If a node is found but the buffer in that node is a subset of the new user buffer, the node is extended with the new buffer pages. Both modes of operation require (re-)insertion into the interval RB tree. When the node being inserted is a new node, the operations are pretty simple. However, when the node is already existing and is being extended, special care must be taken. First, we want to guard against an asynchronous attempt to delete the node by the MMU invalidation notifier. The simplest way to do this is to remove the node from the RB tree, preventing the search algorithm from finding it. Second, the node needs to be re-inserted so it lands in the proper place in the tree and the tree is correctly re-balanced. This also requires the node to be removed from the RB tree. This commit adds the hfi1_mmu_rb_extract() function, which will search for a node in the interval RB tree matching an address and length and remove it from the RB tree if found. This allows for both of the above special cases be handled in a single step. Reviewed-by: Dean Luick Signed-off-by: Mitko Haralanov Signed-off-by: Dennis Dalessandro Signed-off-by: Doug Ledford --- drivers/staging/rdma/hfi1/mmu_rb.c | 19 +++++++++++++++++++ drivers/staging/rdma/hfi1/mmu_rb.h | 2 ++ drivers/staging/rdma/hfi1/user_sdma.c | 33 ++++++++++++++------------------- 3 files changed, 35 insertions(+), 19 deletions(-) diff --git a/drivers/staging/rdma/hfi1/mmu_rb.c b/drivers/staging/rdma/hfi1/mmu_rb.c index a1aaaea..03f360a 100644 --- a/drivers/staging/rdma/hfi1/mmu_rb.c +++ b/drivers/staging/rdma/hfi1/mmu_rb.c @@ -239,6 +239,25 @@ struct mmu_rb_node *hfi1_mmu_rb_search(struct rb_root *root, unsigned long addr, return node; } +struct mmu_rb_node *hfi1_mmu_rb_extract(struct rb_root *root, + unsigned long addr, unsigned long len) +{ + struct mmu_rb_handler *handler = find_mmu_handler(root); + struct mmu_rb_node *node; + unsigned long flags; + + if (!handler) + return ERR_PTR(-EINVAL); + + spin_lock_irqsave(&handler->lock, flags); + node = __mmu_rb_search(handler, addr, len); + if (node) + __mmu_int_rb_remove(node, handler->root); + spin_unlock_irqrestore(&handler->lock, flags); + + return node; +} + void hfi1_mmu_rb_remove(struct rb_root *root, struct mmu_rb_node *node) { struct mmu_rb_handler *handler = find_mmu_handler(root); diff --git a/drivers/staging/rdma/hfi1/mmu_rb.h b/drivers/staging/rdma/hfi1/mmu_rb.h index 19a306e..7a57b9c4 100644 --- a/drivers/staging/rdma/hfi1/mmu_rb.h +++ b/drivers/staging/rdma/hfi1/mmu_rb.h @@ -70,5 +70,7 @@ int hfi1_mmu_rb_insert(struct rb_root *, struct mmu_rb_node *); void hfi1_mmu_rb_remove(struct rb_root *, struct mmu_rb_node *); struct mmu_rb_node *hfi1_mmu_rb_search(struct rb_root *, unsigned long, unsigned long); +struct mmu_rb_node *hfi1_mmu_rb_extract(struct rb_root *, unsigned long, + unsigned long); #endif /* _HFI1_MMU_RB_H */ diff --git a/drivers/staging/rdma/hfi1/user_sdma.c b/drivers/staging/rdma/hfi1/user_sdma.c index d1645d9..f7e2fe7 100644 --- a/drivers/staging/rdma/hfi1/user_sdma.c +++ b/drivers/staging/rdma/hfi1/user_sdma.c @@ -1062,9 +1062,9 @@ static int pin_vector_pages(struct user_sdma_request *req, struct sdma_mmu_node *node = NULL; struct mmu_rb_node *rb_node; - rb_node = hfi1_mmu_rb_search(&pq->sdma_rb_root, - (unsigned long)iovec->iov.iov_base, - iovec->iov.iov_len); + rb_node = hfi1_mmu_rb_extract(&pq->sdma_rb_root, + (unsigned long)iovec->iov.iov_base, + iovec->iov.iov_len); if (rb_node && !IS_ERR(rb_node)) node = container_of(rb_node, struct sdma_mmu_node, rb); else @@ -1131,25 +1131,20 @@ retry: iovec->pages = node->pages; iovec->npages = npages; - if (!rb_node) { - ret = hfi1_mmu_rb_insert(&req->pq->sdma_rb_root, &node->rb); - if (ret) { - spin_lock(&pq->evict_lock); - if (!list_empty(&node->list)) - list_del(&node->list); - pq->n_locked -= node->npages; - spin_unlock(&pq->evict_lock); - unpin_vector_pages(current->mm, node->pages, 0, - node->npages); - goto bail; - } - } else { - atomic_inc(&node->refcount); + ret = hfi1_mmu_rb_insert(&req->pq->sdma_rb_root, &node->rb); + if (ret) { + spin_lock(&pq->evict_lock); + if (!list_empty(&node->list)) + list_del(&node->list); + pq->n_locked -= node->npages; + spin_unlock(&pq->evict_lock); + goto bail; } return 0; bail: - if (!rb_node) - kfree(node); + if (rb_node) + unpin_vector_pages(current->mm, node->pages, 0, node->npages); + kfree(node); return ret; } -- 2.7.4