[newlib-cygwin] Cygwin: pthread_cond_wait: Do as Linux and BSD do.

Corinna Vinschen corinna@sourceware.org
Tue Mar 7 14:18:00 GMT 2017


https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=49505a907f3fb690e7db81dde9b70067664c1d83

commit 49505a907f3fb690e7db81dde9b70067664c1d83
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Tue Mar 7 15:15:47 2017 +0100

    Cygwin: pthread_cond_wait: Do as Linux and BSD do.
    
    POSIX states as follows about pthread_cond_wait:
    If a signal is delivered to a thread waiting for a condition variable,
    upon return from the signal handler the thread resumes waiting for the
    condition variable as if it was not interrupted, or it returns zero
    due to spurious wakeup.
    
    Cygwin so far employs the latter behaviour, while Linux and BSD employ
    the former one.
    
    Align Cygwin behaviour to Linux and BSD.
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/thread.cc | 27 +++++----------------------
 1 file changed, 5 insertions(+), 22 deletions(-)

diff --git a/winsup/cygwin/thread.cc b/winsup/cygwin/thread.cc
index 7084657..8cae82c 100644
--- a/winsup/cygwin/thread.cc
+++ b/winsup/cygwin/thread.cc
@@ -1266,24 +1266,14 @@ pthread_cond::wait (pthread_mutex_t mutex, PLARGE_INTEGER timeout)
   ++mutex->condwaits;
   mutex->unlock ();
 
-  rv = cygwait (sem_wait, timeout, cw_cancel | cw_sig_eintr);
+  rv = cygwait (sem_wait, timeout, cw_cancel | cw_sig_restart);
 
   mtx_out.lock ();
 
-  if (rv != WAIT_OBJECT_0)
-    {
-      /*
-       * It might happen that a signal is sent while the thread got canceled
-       * or timed out. Try to take one.
-       * If the thread gets one than a signal|broadcast is in progress.
-       */
-      if (WaitForSingleObject (sem_wait, 0) == WAIT_OBJECT_0)
-	/*
-	 * thread got cancelled ot timed out while a signalling is in progress.
-	 * Set wait result back to signaled
-	 */
-	rv = WAIT_OBJECT_0;
-    }
+  if (rv != WAIT_OBJECT_0 && WaitForSingleObject (sem_wait, 0) == WAIT_OBJECT_0)
+    /* Thread got cancelled ot timed out while a signalling is in progress.
+       Set wait result back to signaled */
+    rv = WAIT_OBJECT_0;
 
   InterlockedDecrement (&waiting);
 
@@ -1301,13 +1291,6 @@ pthread_cond::wait (pthread_mutex_t mutex, PLARGE_INTEGER timeout)
 
   if (rv == WAIT_CANCELED)
     pthread::static_cancel_self ();
-  else if (rv == WAIT_SIGNALED)
-    /* SUSv3 states:  If a signal is delivered to a thread waiting for a
-       condition variable, upon return from the signal handler the thread
-       resumes waiting for the condition variable as if it was not
-       interrupted, or it shall return zero due to spurious wakeup.
-       We opt for the latter choice here. */
-    return 0;
   else if (rv == WAIT_TIMEOUT)
     return ETIMEDOUT;



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