Non-SFI mode: Add Linux asynchronous signal support

src/untrusted/pthread/nc_thread.c

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /*
  * Native Client threads library
  */
 
@@ skipping 18 matching lines @@
 #include "native_client/src/untrusted/valgrind/dynamic_annotations.h"
 
 #if defined(NACL_IN_IRT)
 # include "native_client/src/untrusted/irt/irt_private.h"
 #endif
 
 /*
  * ABI tables for underyling NaCl thread interfaces. This is declared to be
  * global so that a user will be able to override it using the irt_ext API.
  */
-struct nacl_irt_thread __libnacl_irt_thread;
+struct nacl_irt_thread_v0_2 __libnacl_irt_thread;
 
 /*
  * These days, the thread_create() syscall/IRT call will align the
  * stack for us, but for compatibility with older, released x86
  * versions of NaCl where thread_create() does not align the stack, we
  * align the stack ourselves.
  */
 #if defined(__i386__)
 static const uint32_t kStackAlignment = 32;
 static const uint32_t kStackPadBelowAlign = 4;  /* Return address size */
@@ skipping 358 matching lines @@
    * zero address of architecture-dependent width, needed to satisfy the
    * normal ABI alignment requirements for the stack.  (On some machines
    * this is the dummy return address of the thread-start function.)
    *
    * Both thread_stack and stacksize are multiples of 16.
    */
   esp = (void *) (thread_stack + stacksize - kStackPadBelowAlign);
   memset(esp, 0, kStackPadBelowAlign);
 
   /* Start the thread. */
-  retval = __libnacl_irt_thread.thread_create(nc_thread_starter, esp, new_tp);
+  nacl_irt_tid_t native_tid;
+  retval = __libnacl_irt_thread.thread_create(nc_thread_starter, esp, new_tp,

[Mark Seaborn, 2015/06/26 18:32:00]

This isn't going to work for SFI NaCl, because you're making this depend on
nacl_irt_thread_v0_2, which isn't defined for SFI NaCl.

I'm not sure if this change passes on the trybots?  (Can you figure out how to
get trybot access?)

I don't think it's really necessary to add support for TIDs to
src/untrusted/pthread/ (i.e. to nacl-newlib's libpthread), because in the NaCl
codebase we *should* only need access to them for testing.

See my other comment on the test code.

[Luis Héctor Chávez, 2015/07/06 23:45:00]

Done.

+                                              &native_tid);
+  (*thread_id)->native_tid = native_tid;

[Mark Seaborn, 2015/06/26 18:32:00]

BTW, assigning to (*thread_id)->native_tid as a separate step defeats the
purpose of having thread_create() set the TID rather than having a separate
gettid() syscall, which is to make both the assignment and the use of the TID
thread-safe.

Doing the assignment here means that it's not thread-safe for the child thread
to cause pthread_kill(child_thread, sig) to be called.

Also, the thread could have exited by this point, so (*thread_id)->native_tid
might point to deallocated memory.

The idea would have been to pass &(*thread_id)->native_tid to thread_create().

[Luis Héctor Chávez, 2015/07/06 23:45:00]

Done.

   if (0 != retval) {
     pthread_mutex_lock(&__nc_thread_management_lock);
     /* TODO(gregoryd) : replace with atomic decrement? */
     --__nc_running_threads_counter;
     pthread_mutex_unlock(&__nc_thread_management_lock);
     goto ret;
   }
 
   assert(0 == retval);
 
@@ skipping 381 matching lines @@
 
 /*
  * We include this directly in this file rather than compiling it
  * separately because there is some code (e.g. libstdc++) that uses weak
  * references to all pthread functions, but conditionalizes its calls only
  * on one symbol.  So if these functions are in another file in a library
  * archive, they might not be linked in by static linking.
  */
 /* @IGNORE_LINES_FOR_CODE_HYGIENE[1] */
 #include "native_client/src/untrusted/pthread/nc_tsd.c"