[dpdk-dev] [PATCH v6 14/21] malloc: allow removing memory from named heaps

[Anatoly Burakov <anatoly.burakov@intel.com>]

Add an API to remove memory from specified heaps. This will first
check if all elements within the region are free, and that the
region is the original region that was added to the heap (by
comparing its length to length of memory addressed by the
underlying memseg list).

Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 lib/librte_eal/common/include/rte_malloc.h | 27 +++++++++++
 lib/librte_eal/common/malloc_heap.c        | 54 ++++++++++++++++++++++
 lib/librte_eal/common/malloc_heap.h        |  4 ++
 lib/librte_eal/common/rte_malloc.c         | 39 ++++++++++++++++
 lib/librte_eal/rte_eal_version.map         |  1 +
 5 files changed, 125 insertions(+)

diff --git a/lib/librte_eal/common/include/rte_malloc.h b/lib/librte_eal/common/include/rte_malloc.h
index fb5b6e2f7..40bae4478 100644
--- a/lib/librte_eal/common/include/rte_malloc.h
+++ b/lib/librte_eal/common/include/rte_malloc.h
@@ -302,6 +302,33 @@ int __rte_experimental
 rte_malloc_heap_memory_add(const char *heap_name, void *va_addr, size_t len,
 		rte_iova_t iova_addrs[], unsigned int n_pages, size_t page_sz);
 
+/**
+ * Remove memory chunk from heap with specified name.
+ *
+ * @note Memory chunk being removed must be the same as one that was added;
+ *   partially removing memory chunks is not supported
+ *
+ * @note Memory area must not contain any allocated elements to allow its
+ *   removal from the heap
+ *
+ * @param heap_name
+ *   Name of the heap to remove memory from
+ * @param va_addr
+ *   Virtual address to remove from the heap
+ * @param len
+ *   Length of virtual area to remove from the heap
+ *
+ * @return
+ *   - 0 on success
+ *   - -1 in case of error, with rte_errno set to one of the following:
+ *     EINVAL - one of the parameters was invalid
+ *     EPERM  - attempted to remove memory from a reserved heap
+ *     ENOENT - heap or memory chunk was not found
+ *     EBUSY  - memory chunk still contains data
+ */
+int __rte_experimental
+rte_malloc_heap_memory_remove(const char *heap_name, void *va_addr, size_t len);
+
 /**
  * Creates a new empty malloc heap with a specified name.
  *
diff --git a/lib/librte_eal/common/malloc_heap.c b/lib/librte_eal/common/malloc_heap.c
index 36bfd53d3..c52d84419 100644
--- a/lib/librte_eal/common/malloc_heap.c
+++ b/lib/librte_eal/common/malloc_heap.c
@@ -1019,6 +1019,32 @@ malloc_heap_dump(struct malloc_heap *heap, FILE *f)
 	rte_spinlock_unlock(&heap->lock);
 }
 
+static int
+destroy_seg(struct malloc_elem *elem, size_t len)
+{
+	struct malloc_heap *heap = elem->heap;
+	struct rte_memseg_list *msl;
+
+	msl = elem->msl;
+
+	/* this element can be removed */
+	malloc_elem_free_list_remove(elem);
+	malloc_elem_hide_region(elem, elem, len);
+
+	heap->total_size -= len;
+
+	memset(elem, 0, sizeof(*elem));
+
+	/* destroy the fbarray backing this memory */
+	if (rte_fbarray_destroy(&msl->memseg_arr) < 0)
+		return -1;
+
+	/* reset the memseg list */
+	memset(msl, 0, sizeof(*msl));
+
+	return 0;
+}
+
 int
 malloc_heap_add_external_memory(struct malloc_heap *heap, void *va_addr,
 		rte_iova_t iova_addrs[], unsigned int n_pages, size_t page_sz)
@@ -1093,6 +1119,34 @@ malloc_heap_add_external_memory(struct malloc_heap *heap, void *va_addr,
 	return 0;
 }
 
+int
+malloc_heap_remove_external_memory(struct malloc_heap *heap, void *va_addr,
+		size_t len)
+{
+	struct malloc_elem *elem = heap->first;
+
+	/* find element with specified va address */
+	while (elem != NULL && elem != va_addr) {
+		elem = elem->next;
+		/* stop if we've blown past our VA */
+		if (elem > (struct malloc_elem *)va_addr) {
+			rte_errno = ENOENT;
+			return -1;
+		}
+	}
+	/* check if element was found */
+	if (elem == NULL || elem->msl->len != len) {
+		rte_errno = ENOENT;
+		return -1;
+	}
+	/* if element's size is not equal to segment len, segment is busy */
+	if (elem->state == ELEM_BUSY || elem->size != len) {
+		rte_errno = EBUSY;
+		return -1;
+	}
+	return destroy_seg(elem, len);
+}
+
 int
 malloc_heap_create(struct malloc_heap *heap, const char *heap_name)
 {
diff --git a/lib/librte_eal/common/malloc_heap.h b/lib/librte_eal/common/malloc_heap.h
index 237ce9dc2..e48996d52 100644
--- a/lib/librte_eal/common/malloc_heap.h
+++ b/lib/librte_eal/common/malloc_heap.h
@@ -43,6 +43,10 @@ int
 malloc_heap_add_external_memory(struct malloc_heap *heap, void *va_addr,
 		rte_iova_t iova_addrs[], unsigned int n_pages, size_t page_sz);
 
+int
+malloc_heap_remove_external_memory(struct malloc_heap *heap, void *va_addr,
+		size_t len);
+
 int
 malloc_heap_free(struct malloc_elem *elem);
 
diff --git a/lib/librte_eal/common/rte_malloc.c b/lib/librte_eal/common/rte_malloc.c
index acdbd92a2..bfc49d0b7 100644
--- a/lib/librte_eal/common/rte_malloc.c
+++ b/lib/librte_eal/common/rte_malloc.c
@@ -379,6 +379,45 @@ rte_malloc_heap_memory_add(const char *heap_name, void *va_addr, size_t len,
 	return ret;
 }
 
+int
+rte_malloc_heap_memory_remove(const char *heap_name, void *va_addr, size_t len)
+{
+	struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
+	struct malloc_heap *heap = NULL;
+	int ret;
+
+	if (heap_name == NULL || va_addr == NULL || len == 0 ||
+			strnlen(heap_name, RTE_HEAP_NAME_MAX_LEN) == 0 ||
+			strnlen(heap_name, RTE_HEAP_NAME_MAX_LEN) ==
+				RTE_HEAP_NAME_MAX_LEN) {
+		rte_errno = EINVAL;
+		return -1;
+	}
+	rte_rwlock_write_lock(&mcfg->memory_hotplug_lock);
+	/* find our heap */
+	heap = find_named_heap(heap_name);
+	if (heap == NULL) {
+		rte_errno = ENOENT;
+		ret = -1;
+		goto unlock;
+	}
+	if (heap->socket_id < RTE_MAX_NUMA_NODES) {
+		/* cannot remove memory from internal heaps */
+		rte_errno = EPERM;
+		ret = -1;
+		goto unlock;
+	}
+
+	rte_spinlock_lock(&heap->lock);
+	ret = malloc_heap_remove_external_memory(heap, va_addr, len);
+	rte_spinlock_unlock(&heap->lock);
+
+unlock:
+	rte_rwlock_write_unlock(&mcfg->memory_hotplug_lock);
+
+	return ret;
+}
+
 int
 rte_malloc_heap_create(const char *heap_name)
 {
diff --git a/lib/librte_eal/rte_eal_version.map b/lib/librte_eal/rte_eal_version.map
index 02254042c..8c66d0be9 100644
--- a/lib/librte_eal/rte_eal_version.map
+++ b/lib/librte_eal/rte_eal_version.map
@@ -322,6 +322,7 @@ EXPERIMENTAL {
 	rte_malloc_heap_destroy;
 	rte_malloc_heap_get_socket;
 	rte_malloc_heap_memory_add;
+	rte_malloc_heap_memory_remove;
 	rte_malloc_heap_socket_is_external;
 	rte_mem_alloc_validator_register;
 	rte_mem_alloc_validator_unregister;
-- 
2.17.1