Fix race in VerifyStackReadWithMultipleThreads

Patch by Chris Dearman <chris@mips.com>
R=ted at http://breakpad.appspot.com/377002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@959 4c0a9323-5329-0410-9bdc-e9ce6186880e

1 files changed, 9 insertions, 8 deletions

diff --git a/src/client/linux/minidump_writer/linux_dumper_unittest_helper.cc b/src/client/linux/minidump_writer/linux_dumper_unittest_helper.cc
index 6e3d5e4b..418e7e67 100644
--- a/src/client/linux/minidump_writer/linux_dumper_unittest_helper.cc
+++ b/src/client/linux/minidump_writer/linux_dumper_unittest_helper.cc
@@ -51,7 +51,14 @@
 #endif
 
 void *thread_function(void *data) {
+  int pipefd = *static_cast<int *>(data);
   volatile pid_t thread_id = syscall(__NR_gettid);
+  // Signal parent that a thread has started.
+  uint8_t byte = 1;
+  if (write(pipefd, &byte, sizeof(byte)) != sizeof(byte)) {
+    perror("ERROR: parent notification failed");
+    return NULL;
+  }
   register volatile pid_t *thread_id_ptr asm(TID_PTR_REGISTER) = &thread_id;
   while (true)
     asm volatile ("" : : "r" (thread_id_ptr));
@@ -75,14 +82,8 @@ int main(int argc, char *argv[]) {
   pthread_attr_init(&thread_attributes);
   pthread_attr_setdetachstate(&thread_attributes, PTHREAD_CREATE_DETACHED);
   for (int i = 1; i < num_threads; i++) {
-    pthread_create(&threads[i], &thread_attributes, &thread_function, NULL);
-  }
-  // Signal parent that this process has started all threads.
-  uint8_t byte = 1;
-  if (write(pipefd, &byte, sizeof(byte)) != sizeof(byte)) {
-    perror("ERROR: parent notification failed");
-    return 1;
+    pthread_create(&threads[i], &thread_attributes, &thread_function, &pipefd);
   }
-  thread_function(NULL);
+  thread_function(&pipefd);
   return 0;
 }