[dpdk-dev] [PATCH] ACL: use setjmp/longjmp to handle memory allocation failure at build phase

[Konstantin Ananyev <konstantin.ananyev@intel.com>]

During build phase ACL doing quite a lot of memory allocations
for relatively small temporary structures.
In theory each of such allocation can fail, so we need to handle
all these possible failures.
That adds a lot of extra checks and makes the code harder to read and follow.
To simplify the process, made changes to handle all such failures
in one place.
Note, that all that memory for temporary structures
is freed at one go at the end of build phase.

Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
---
 lib/librte_acl/acl_bld.c | 42 +++++++++++++-----------------------------
 lib/librte_acl/tb_mem.c  |  8 ++++++--
 lib/librte_acl/tb_mem.h  |  3 +++
 3 files changed, 22 insertions(+), 31 deletions(-)

diff --git a/lib/librte_acl/acl_bld.c b/lib/librte_acl/acl_bld.c
index 1fe79fb..ddb23fd 100644
--- a/lib/librte_acl/acl_bld.c
+++ b/lib/librte_acl/acl_bld.c
@@ -302,8 +302,6 @@ acl_add_ptr(struct acl_build_context *context,
 		/* add room for more pointers */
 		num_ptrs = node->max_ptrs + ACL_PTR_ALLOC;
 		ptrs = acl_build_alloc(context, num_ptrs, sizeof(*ptrs));
-		if (ptrs == NULL)
-			return -ENOMEM;
 
 		/* copy current points to new memory allocation */
 		if (node->ptrs != NULL) {
@@ -477,16 +475,12 @@ acl_dup_node(struct acl_build_context *context, struct rte_acl_node *node)
 	struct rte_acl_node *next;
 
 	next = acl_alloc_node(context, node->level);
-	if (next == NULL)
-		return NULL;
 
 	/* allocate the pointers */
 	if (node->num_ptrs > 0) {
 		next->ptrs = acl_build_alloc(context,
 			node->max_ptrs,
 			sizeof(struct rte_acl_ptr_set));
-		if (next->ptrs == NULL)
-			return NULL;
 		next->max_ptrs = node->max_ptrs;
 	}
 
@@ -669,8 +663,6 @@ acl_merge_intersect(struct acl_build_context *context,
 
 	/* Duplicate A for intersection */
 	node_c = acl_dup_node(context, node_a->ptrs[idx_a].ptr);
-	if (node_c == NULL)
-		return -1;
 
 	/* Remove intersection from A */
 	acl_exclude_ptr(context, node_a, idx_a, intersect_ptr);
@@ -1328,14 +1320,10 @@ build_trie(struct acl_build_context *context, struct rte_acl_build_rule *head,
 	rule = head;
 
 	trie = acl_alloc_node(context, 0);
-	if (trie == NULL)
-		return NULL;
 
 	while (rule != NULL) {
 
 		root = acl_alloc_node(context, 0);
-		if (root == NULL)
-			return NULL;
 
 		root->ref_count = 1;
 		end = root;
@@ -1419,10 +1407,9 @@ build_trie(struct acl_build_context *context, struct rte_acl_build_rule *head,
 		 * Setup the results for this rule.
 		 * The result and priority of each category.
 		 */
-		if (end->mrt == NULL &&
-				(end->mrt = acl_build_alloc(context, 1,
-				sizeof(*end->mrt))) == NULL)
-			return NULL;
+		if (end->mrt == NULL)
+			end->mrt = acl_build_alloc(context, 1,
+				sizeof(*end->mrt));
 
 		for (m = 0; m < context->cfg.num_categories; m++) {
 			if (rule->f->data.category_mask & (1 << m)) {
@@ -1760,13 +1747,6 @@ acl_build_tries(struct acl_build_context *context,
 
 		/* Create a new copy of config for remaining rules. */
 		config = acl_build_alloc(context, 1, sizeof(*config));
-		if (config == NULL) {
-			RTE_LOG(ERR, ACL,
-				"New config allocation for %u-th "
-				"trie failed\n", num_tries);
-			return -ENOMEM;
-		}
-
 		memcpy(config, rule_sets[n]->config, sizeof(*config));
 
 		/* Make remaining rules use new config. */
@@ -1825,12 +1805,6 @@ acl_build_rules(struct acl_build_context *bcx)
 	sz = ofs + n * fn * sizeof(*wp);
 
 	br = tb_alloc(&bcx->pool, sz);
-	if (br == NULL) {
-		RTE_LOG(ERR, ACL, "ACL context %s: failed to create a copy "
-			"of %u build rules (%zu bytes)\n",
-			bcx->acx->name, n, sz);
-		return -ENOMEM;
-	}
 
 	wp = (uint32_t *)((uintptr_t)br + ofs);
 	num = 0;
@@ -1895,6 +1869,16 @@ acl_bld(struct acl_build_context *bcx, struct rte_acl_ctx *ctx,
 	bcx->category_mask = LEN2MASK(bcx->cfg.num_categories);
 	bcx->node_max = node_max;
 
+	rc = sigsetjmp(bcx->pool.fail, 0);
+
+	/* build phase runs out of memory. */
+	if (rc != 0) {
+		RTE_LOG(ERR, ACL,
+			"ACL context: %s, %s() failed with error code: %d\n",
+			bcx->acx->name, __func__, rc);
+		return rc;
+	}
+
 	/* Create a build rules copy. */
 	rc = acl_build_rules(bcx);
 	if (rc != 0)
diff --git a/lib/librte_acl/tb_mem.c b/lib/librte_acl/tb_mem.c
index fdf3080..157e608 100644
--- a/lib/librte_acl/tb_mem.c
+++ b/lib/librte_acl/tb_mem.c
@@ -37,6 +37,11 @@
  *  Memory management routines for temporary memory.
  *  That memory is used only during build phase and is released after
  *  build is finished.
+ *  Note, that tb_pool/tb_alloc() are not supposed to return NULL.
+ *  Instead, in the case of failure to allocate memory,
+ *  it would do siglongjmp(pool->fail).
+ *  It is responsibility of the caller to save the proper context/environment,
+ *  in the pool->fail before calling tb_alloc() for the given pool first time.
  */
 
 static struct tb_mem_block *
@@ -51,6 +56,7 @@ tb_pool(struct tb_mem_pool *pool, size_t sz)
 	if (block == NULL) {
 		RTE_LOG(ERR, MALLOC, "%s(%zu)\n failed, currently allocated "
 			"by pool: %zu bytes\n", __func__, sz, pool->alloc);
+		siglongjmp(pool->fail, -ENOMEM);
 		return NULL;
 	}
 
@@ -81,8 +87,6 @@ tb_alloc(struct tb_mem_pool *pool, size_t size)
 	if (block == NULL || block->size < size) {
 		new_sz = (size > pool->min_alloc) ? size : pool->min_alloc;
 		block = tb_pool(pool, new_sz);
-		if (block == NULL)
-			return NULL;
 	}
 	ptr = block->mem;
 	block->size -= size;
diff --git a/lib/librte_acl/tb_mem.h b/lib/librte_acl/tb_mem.h
index a8dae94..ca7af96 100644
--- a/lib/librte_acl/tb_mem.h
+++ b/lib/librte_acl/tb_mem.h
@@ -48,6 +48,7 @@ extern "C" {
 #endif
 
 #include <rte_acl_osdep.h>
+#include <setjmp.h>
 
 struct tb_mem_block {
 	struct tb_mem_block *next;
@@ -61,6 +62,8 @@ struct tb_mem_pool {
 	size_t               alignment;
 	size_t               min_alloc;
 	size_t               alloc;
+	/* jump target in case of memory allocation failure. */
+	sigjmp_buf           fail;
 };
 
 void *tb_alloc(struct tb_mem_pool *pool, size_t size);
-- 
1.8.5.3