nptl: Move cancel type out of cancelhandling

Now that the thread cancellation type is not accessed concurrently
anymore, it is possible to move it out the cancelhandling.

By removing the cancel state out of the internal thread cancel handling
state there is no need to check if cancelled bit was set in CAS
operation.

It allows simplifing the cancellation wrappers and the
CANCEL_CANCELED_AND_ASYNCHRONOUS is removed.

Checked on x86_64-linux-gnu and aarch64-linux-gnu.

1 files changed, 5 insertions, 37 deletions

diff --git a/nptl/pthread_setcanceltype.c b/nptl/pthread_setcanceltype.c
index ae5df1d..e7b24ae 100644
--- a/nptl/pthread_setcanceltype.c
+++ b/nptl/pthread_setcanceltype.c
@@ -29,43 +29,11 @@ __pthread_setcanceltype (int type, int *oldtype)
 
   volatile struct pthread *self = THREAD_SELF;
 
-  int oldval = THREAD_GETMEM (self, cancelhandling);
-  while (1)
-    {
-      int newval = (type == PTHREAD_CANCEL_ASYNCHRONOUS
-		    ? oldval | CANCELTYPE_BITMASK
-		    : oldval & ~CANCELTYPE_BITMASK);
-
-      /* Store the old value.  */
-      if (oldtype != NULL)
-	*oldtype = ((oldval & CANCELTYPE_BITMASK)
-		    ? PTHREAD_CANCEL_ASYNCHRONOUS : PTHREAD_CANCEL_DEFERRED);
-
-      /* Avoid doing unnecessary work.  The atomic operation can
-	 potentially be expensive if the memory has to be locked and
-	 remote cache lines have to be invalidated.  */
-      if (oldval == newval)
-	break;
-
-      /* Update the cancel handling word.  This has to be done
-	 atomically since other bits could be modified as well.  */
-      int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
-					      oldval);
-      if (__glibc_likely (curval == oldval))
-	{
-	  if (self->cancelstate == PTHREAD_CANCEL_ENABLE
-	      && CANCEL_CANCELED_AND_ASYNCHRONOUS (newval))
-	    {
-	      THREAD_SETMEM (self, result, PTHREAD_CANCELED);
-	      __do_cancel ();
-	    }
-
-	  break;
-	}
-
-      /* Prepare for the next round.  */
-      oldval = curval;
-    }
+  if (oldtype != NULL)
+    *oldtype = self->canceltype;
+  self->canceltype = type;
+  if (type == PTHREAD_CANCEL_ASYNCHRONOUS)
+    __pthread_testcancel ();
 
   return 0;
 }