Fix race condition

src/core/lib/support/arena.c

@@ -34,6 +34,7 @@
 #include "src/core/lib/support/arena.h"
 #include <grpc/support/alloc.h>
 #include <grpc/support/atm.h>
+#include <grpc/support/log.h>
 #include <grpc/support/useful.h>
 
 #define ROUND_UP_TO_ALIGNMENT_SIZE(x) \
@@ -74,16 +75,16 @@ void *gpr_arena_alloc(gpr_arena *arena, size_t size) {
   size_t start =
       (size_t)gpr_atm_no_barrier_fetch_add(&arena->size_so_far, size);
   zone *z = &arena->initial_zone;
-  while (start > z->size_begin) {
+  while (start > z->size_end) {
     zone *next_z = (zone *)gpr_atm_acq_load(&z->next_atm);
-    while (next_z == NULL) {
-      size_t next_z_size = GPR_MAX(2 * start, size);
+    if (next_z == NULL) {
+      size_t next_z_size = GPR_MAX((size_t)gpr_atm_no_barrier_load(&arena->size_so_far), size);
       next_z = gpr_zalloc(sizeof(zone) + next_z_size);
       next_z->size_begin = z->size_end;
       next_z->size_end = z->size_end + next_z_size;
       if (!gpr_atm_rel_cas(&z->next_atm, (gpr_atm)NULL, (gpr_atm)next_z)) {
         gpr_free(next_z);
-        next_z = NULL;
+        next_z = (zone*)gpr_atm_acq_load(&z->next_atm); 
       }
     }
     z = next_z;
@@ -91,5 +92,7 @@ void *gpr_arena_alloc(gpr_arena *arena, size_t size) {
   if (start + size > z->size_end) {
     return gpr_arena_alloc(arena, size);
   }
+  GPR_ASSERT(start >= z->size_begin);
+  GPR_ASSERT(start + size <= z->size_end);
   return ((char *)(z + 1)) + start - z->size_begin;
 }

test/core/support/arena_test.c

@@ -76,6 +76,7 @@ static void test(const char *name, size_t init_size, const size_t *allocs,
     memset(ps[i], 1, allocs[i]);
   }
   gpr_arena_destroy(a);
+  gpr_free(ps);
 }
 
 #define TEST(name, init_size, ...)                     \
@@ -99,6 +100,8 @@ static void concurrent_test_body(void *arg) {
 }
 
 static void concurrent_test(void) {
+  gpr_log(GPR_DEBUG, "concurrent_test");
+
   concurrent_test_args args;
   gpr_event_init(&args.ev_start);
   args.arena = gpr_arena_create(1024);
@@ -107,7 +110,7 @@ static void concurrent_test(void) {
 
   for (int i = 0; i < CONCURRENT_TEST_THREADS; i++) {
     gpr_thd_options opt = gpr_thd_options_default();
-    gpr_thd_options_is_joinable(&opt);
+    gpr_thd_options_set_joinable(&opt);
     gpr_thd_new(&thds[i], concurrent_test_body, &args, &opt);
   }
 
@@ -116,6 +119,8 @@ static void concurrent_test(void) {
   for (int i = 0; i < CONCURRENT_TEST_THREADS; i++) {
     gpr_thd_join(thds[i]);
   }
+
+  gpr_arena_destroy(args.arena);
 }
 
 int main(int argc, char *argv[]) {