commit 63668b7084ac26865136e59fdf17781f9f49bd99

Author: Torvald Riegel <triegel@redhat.com>

Date:   Fri Oct 11 18:58:04 2013 +0300

    pthread_once: Clean up constants.

    [BZ #15215] This just gives a name to the integer constants being used.

diff --git a/nptl/pthreadP.h b/nptl/pthreadP.h

index dda1032d5aa95234..1a842e06bff82479 100644

--- a/nptl/pthreadP.h

+++ b/nptl/pthreadP.h

@@ -159,6 +159,12 @@ enum

 #define FUTEX_TID_MASK		0x3fffffff

+/* pthread_once definitions.  See __pthread_once for how these are used.  */

+#define __PTHREAD_ONCE_INPROGRESS	1

+#define __PTHREAD_ONCE_DONE		2

+#define __PTHREAD_ONCE_FORK_GEN_INCR	4

+

+

 /* Internal variables.  */

diff --git a/nptl/pthread_once.c b/nptl/pthread_once.c

index 10c01d6023508e3c..595bd7e298003e00 100644

--- a/nptl/pthread_once.c

+++ b/nptl/pthread_once.c

@@ -40,8 +40,11 @@ clear_once_control (void *arg)

 /* This is similar to a lock implementation, but we distinguish between three

-   states: not yet initialized (0), initialization finished (2), and

-   initialization in progress (__fork_generation | 1).  If in the first state,

+   states: not yet initialized (0), initialization in progress

+   (__fork_generation | __PTHREAD_ONCE_INPROGRESS), and initialization

+   finished (__PTHREAD_ONCE_DONE); __fork_generation does not use the bits

+   that are used for __PTHREAD_ONCE_INPROGRESS and __PTHREAD_ONCE_DONE (which

+   is what __PTHREAD_ONCE_FORK_GEN_INCR is used for).  If in the first state,

    threads will try to run the initialization by moving to the second state;

    the first thread to do so via a CAS on once_control runs init_routine,

    other threads block.

@@ -66,14 +69,14 @@ __pthread_once (once_control, init_routine)

       int oldval, val, newval;

       /* We need acquire memory order for this load because if the value

-         signals that initialization has finished, we need to be see any

+         signals that initialization has finished, we need to see any

          data modifications done during initialization.  */

       val = *once_control;

       atomic_read_barrier();

       do

 	{

 	  /* Check if the initialization has already been done.  */

-	  if (__glibc_likely ((val & 2) != 0))

+	  if (__glibc_likely ((val & __PTHREAD_ONCE_DONE) != 0))

 	    return 0;

 	  oldval = val;

@@ -82,7 +85,7 @@ __pthread_once (once_control, init_routine)

 	     generation because it's immutable in a particular process, and

 	     forked child processes start with a single thread that modified

 	     the generation.  */

-	  newval = __fork_generation | 1;

+	  newval = __fork_generation | __PTHREAD_ONCE_INPROGRESS;

 	  /* We need acquire memory order here for the same reason as for the

 	     load from once_control above.  */

 	  val = atomic_compare_and_exchange_val_acq (once_control, newval,

@@ -91,11 +94,11 @@ __pthread_once (once_control, init_routine)

       while (__glibc_unlikely (val != oldval));

       /* Check if another thread already runs the initializer.	*/

-      if ((oldval & 1) != 0)

+      if ((oldval & __PTHREAD_ONCE_INPROGRESS) != 0)

 	{

 	  /* Check whether the initializer execution was interrupted by a

-	     fork.  We know that for both values, bit 0 is set and bit 1 is

-	     not.  */

+	     fork.  We know that for both values, __PTHREAD_ONCE_INPROGRESS

+	     is set and __PTHREAD_ONCE_DONE is not.  */

 	  if (oldval == newval)

 	    {

 	      /* Same generation, some other thread was faster. Wait.  */

@@ -118,7 +121,7 @@ __pthread_once (once_control, init_routine)

          release memory order here because we need to synchronize with other

          threads that want to use the initialized data.  */

       atomic_write_barrier();

-      *once_control = 2;

+      *once_control = __PTHREAD_ONCE_DONE;

       /* Wake up all other threads.  */

       lll_futex_wake (once_control, INT_MAX, LLL_PRIVATE);

diff --git a/nptl/sysdeps/unix/sysv/linux/fork.c b/nptl/sysdeps/unix/sysv/linux/fork.c

index 0635bfdb6cdf0aa8..8c197cb8e4347959 100644

--- a/nptl/sysdeps/unix/sysv/linux/fork.c

+++ b/nptl/sysdeps/unix/sysv/linux/fork.c

@@ -146,8 +146,9 @@ __libc_fork (void)

       assert (THREAD_GETMEM (self, tid) != ppid);

+      /* See __pthread_once.  */

       if (__fork_generation_pointer != NULL)

-	*__fork_generation_pointer += 4;

+	*__fork_generation_pointer += __PTHREAD_ONCE_FORK_GEN_INCR;

       /* Adjust the PID field for the new process.  */

       THREAD_SETMEM (self, pid, THREAD_GETMEM (self, tid));