Re: [PATCH] PowerPC: Define __PTHREAD_MUTEX_HAVE_ELISION to 0

[Siddhesh Poyarekar <siddhesh at redhat dot com>]

On Tue, Mar 25, 2014 at 01:03:11PM -0300, Adhemerval Zanella wrote:
> I agree with you, but the patch to check if it is defined in nptl/sysdeps/pthread/pthread.h
> was rejected: https://sourceware.org/ml/libc-alpha/2014-03/msg00494.html. So I just folowed
> the way x86_64 and s390 does. If this was just an warning I'd rework it to make it more general,
> as Roland as suggested in https://sourceware.org/ml/libc-alpha/2014-03/msg00501.html; but it is
> breaking 'make check' build. So my preference now is let it as and focus on a proper fix, if
> any, after.

Perhaps it would be acceptable to define __PTHREAD_MUTEX_HAVE_ELISION
unconditionally in pthread.h and then redefine it in x86_64 and s390
like so:

diff --git a/nptl/sysdeps/pthread/pthread.h b/nptl/sysdeps/pthread/pthread.h
index 1e0c5dc..524b8c4 100644
--- a/nptl/sysdeps/pthread/pthread.h
+++ b/nptl/sysdeps/pthread/pthread.h
@@ -23,6 +23,8 @@
 #include <sched.h>
 #include <time.h>
 
+#define __PTHREAD_MUTEX_HAVE_ELISION 0
+
 #include <bits/pthreadtypes.h>
 #include <bits/setjmp.h>
 #include <bits/wordsize.h>
diff --git a/nptl/sysdeps/unix/sysv/linux/x86/bits/pthreadtypes.h b/nptl/sysdeps/unix/sysv/linux/x86/bits/pthreadtypes.h
index 28e5144..8548d9d 100644
--- a/nptl/sysdeps/unix/sysv/linux/x86/bits/pthreadtypes.h
+++ b/nptl/sysdeps/unix/sysv/linux/x86/bits/pthreadtypes.h
@@ -84,6 +84,7 @@ typedef struct __pthread_internal_slist
 } __pthread_slist_t;
 #endif
 
+#undef __PTHREAD_MUTEX_HAVE_ELISION
 
 /* Data structures for mutex handling.  The structure of the attribute
    type is not exposed on purpose.  */


or alternatively, define __PTHREAD_MUTEX_HAVE_ELISION to 0 if it is
not yet defined, which is a variant of Will's original fix:

diff --git a/nptl/sysdeps/pthread/pthread.h b/nptl/sysdeps/pthread/pthread.h
index 1e0c5dc..deeea0d 100644
--- a/nptl/sysdeps/pthread/pthread.h
+++ b/nptl/sysdeps/pthread/pthread.h
@@ -27,6 +27,9 @@
 #include <bits/setjmp.h>
 #include <bits/wordsize.h>
 
+#ifndef __PTHREAD_MUTEX_HAVE_ELISION
+# define __PTHREAD_MUTEX_HAVE_ELISION 0
+#endif
 
 /* Detach state.  */
 enum

Both approaches ensure that the macro is always defined and hence look
typo-proof to me.

Siddhesh

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