stream: improve error handling of ssn/segment pools

With large number of threads the default memcaps lead to pool setup
failures. Make sure these are reported properly so that the user
knows what is going on.

Bug: #2226

src/stream-tcp-reassemble.c

@@ -444,8 +444,11 @@ TcpReassemblyThreadCtx *StreamTcpReassembleInitThreadCtx(ThreadVars *tv)
                 ra_ctx->segment_thread_pool_id);
     }
     SCMutexUnlock(&segment_thread_pool_mutex);
-    if (ra_ctx->segment_thread_pool_id < 0 || segment_thread_pool == NULL)
-        abort();
+    if (ra_ctx->segment_thread_pool_id < 0 || segment_thread_pool == NULL) {
+        SCLogError(SC_ERR_MEM_ALLOC, "failed to setup/expand stream segment pool. Expand stream.reassembly.memcap?");
+        StreamTcpReassembleFreeThreadCtx(ra_ctx);
+        SCReturnPtr(NULL, "TcpReassemblyThreadCtx");
+    }
 
     SCReturnPtr(ra_ctx, "TcpReassemblyThreadCtx");
 }

src/stream-tcp.c

@@ -4984,8 +4984,10 @@ TmEcode StreamTcpThreadInit(ThreadVars *tv, void *initdata, void **data)
         SCLogDebug("pool size %d, thread ssn_pool_id %d", PoolThreadSize(ssn_pool), stt->ssn_pool_id);
     }
     SCMutexUnlock(&ssn_pool_mutex);
-    if (stt->ssn_pool_id < 0 || ssn_pool == NULL)
+    if (stt->ssn_pool_id < 0 || ssn_pool == NULL) {
+        SCLogError(SC_ERR_MEM_ALLOC, "failed to setup/expand stream session pool. Expand stream.memcap?");
         SCReturnInt(TM_ECODE_FAILED);
+    }
 
     SCReturnInt(TM_ECODE_OK);
 }