[Valgrind-developers] valgrind/coregrind

[Tom H. <th...@cy...>]

CVS commit by thughes: 

If a thread is waiting on a mutex or condition variable when a signal is
delivered that the thread state is temporarily changed from WaitMX or WaitCV
to Running while the signal handler is running. The original state is then
restored when the handler returns.

This patch forces the associated_mx and associated_cv values to be cleared
at the same time and the original values restored afterwards. Without this
the scheduler state will not be considered sane while the handler is running.

This is based on a patch from Kenneth Schalk and fixes a problem he had
with posting to a semaphore in a signal handler. It also allows a couple
of assertions in the scheduler sanity check to be uncommented.

BUG: 72082


  M +2 -4      vg_scheduler.c   1.188
  M +6 -0      vg_signals.c   1.95
  M +9 -0      x86/signal.c   1.3


--- valgrind/coregrind/vg_scheduler.c  #1.187:1.188
@@ -3237,8 +3237,6 @@ void scheduler_sanity ( void )
          vg_assert(mx != NULL);
       } else {
-         /* Unfortunately these don't hold true when a sighandler is
-            running.  To be fixed. */
-         /* vg_assert(cv == NULL); */
-         /* vg_assert(mx == NULL); */
+         vg_assert(cv == NULL);
+         vg_assert(mx == NULL);
       }
 

--- valgrind/coregrind/vg_signals.c  #1.94:1.95
@@ -1596,4 +1596,10 @@ void VG_(deliver_signal) ( ThreadId tid,
       }
 
+      /* Clear the associated mx/cv information as we are no longer
+         waiting on anything. The original details will be restored
+         when the signal frame is popped. */
+      tst->associated_mx = NULL;
+      tst->associated_cv = NULL;
+
       /* handler gets the union of the signal's mask and the thread's
          mask */

--- valgrind/coregrind/x86/signal.c  #1.2:1.3
@@ -110,4 +110,7 @@ typedef
          delivering this signal? */
       ThreadStatus status;
+      void* /*pthread_mutex_t* */ associated_mx;
+      void* /*pthread_cond_t* */ associated_cv;
+
       /* Sanity check word.  Is the highest-addressed word; do not
          move!*/
@@ -270,4 +273,7 @@ void VGA_(push_signal_frame)(ThreadId ti
       frame->status = tst->status;
 
+   frame->associated_mx = tst->associated_mx;
+   frame->associated_cv = tst->associated_cv;
+
    frame->magicE     = 0x27182818;
 
@@ -343,4 +349,7 @@ Int VGA_(pop_signal_frame)(ThreadId tid)
    tst->status    = frame->status;
 
+   tst->associated_mx = frame->associated_mx;
+   tst->associated_cv = frame->associated_cv;
+
    tst->sig_mask  = frame->mask;