abort might not flush all open streams before process termination (was: aarch64-suse-linux-gnu: libgomp.oacc-c-c++-common/abort-1.c, libgomp.oacc-c-c++-common/abort-3.c FAILs)

abort might not flush all open streams before process termination (was: aarch64-suse-linux-gnu: libgomp.oacc-c-c++-common/abort-1.c, libgomp.oacc-c-c++-common/abort-3.c FAILs)

[Thomas Schwinge]

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Hi!

Copying glibc for your information/in case anyone has any further
comments, and the man-pages maintainer, Michael Kerrisk.  The issue is
that abort might not flush all open streams before process termination;
original thread starting at
<http://news.gmane.org/find-root.php?message_id=%3C87twq4p9f4.fsf%40kepler.schwinge.homeip.net%3E>.

On Tue, 06 Oct 2015 13:55:00 +0200, Andreas Schwab <schwab@linux-m68k.org> wrote:
> Thomas Schwinge <thomas@codesourcery.com> writes:
> 
> > | The two regressed test cases use __builtin_printf instead of fprintf to
> > | stderr, but as far as I know, abort is to flush all open streams before
> > | process termination?
> 
> It can't, since abort must be async-signal-safe.

It's still surprising to me that the message written to stderr is lost in
your aarch64-suse-linux-gnu configuration (only): from a quick look,
(current) glibc's stdlib/abort.c tries to actually close/flush all open
streams before process termination.  This is also what's documented on
<http://man7.org/linux/man-pages/man3/abort.3.html>: "all open streams
are closed and flushed".
<http://pubs.opengroup.org/onlinepubs/9699919799/functions/abort.html>
does sound more "conservative": "[abort] may include an attempt to effect
fclose() on all open streams".  Should the man-page be edited to that
effect?  And, the following patch be applied to GCC?

commit e270bce5dadf61b838706c4cfb824fa9dd22fb93
Author: Thomas Schwinge <thomas@codesourcery.com>
Date:   Wed Oct 7 11:52:15 2015 +0200

    abort might not flush all open streams before process termination
    
    	libgomp/
    	* testsuite/libgomp.oacc-c-c++-common/abort-1.c: Print to stderr.
    	* testsuite/libgomp.oacc-c-c++-common/abort-3.c: Likewise.
---
 libgomp/testsuite/libgomp.oacc-c-c++-common/abort-1.c | 3 ++-
 libgomp/testsuite/libgomp.oacc-c-c++-common/abort-3.c | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/abort-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/abort-1.c
index 6a9b1df..296708f 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/abort-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/abort-1.c
@@ -1,11 +1,12 @@
 /* { dg-do run } */
 
+#include <stdio.h>
 #include <stdlib.h>
 
 int
 main (void)
 {
-  __builtin_printf ("CheCKpOInT\n");
+  fprintf (stderr, "CheCKpOInT\n");
 #pragma acc parallel
   {
     abort ();
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/abort-3.c libgomp/testsuite/libgomp.oacc-c-c++-common/abort-3.c
index 2c8f347..bca425e 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/abort-3.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/abort-3.c
@@ -1,11 +1,12 @@
 /* { dg-do run } */
 
+#include <stdio.h>
 #include <stdlib.h>
 
 int
 main (void)
 {
-  __builtin_printf ("CheCKpOInT\n");
+  fprintf (stderr, "CheCKpOInT\n");
 #pragma acc kernels
   {
     abort ();


Grüße,
 Thomas

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Re: abort might not flush all open streams before process termination

[Andreas Schwab]

Thomas Schwinge <thomas-qD8j1LwMmJjtCj0u4l0SBw@public.gmane.org> writes:

> On Tue, 06 Oct 2015 13:55:00 +0200, Andreas Schwab <schwab-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org> wrote:
>> Thomas Schwinge <thomas-qD8j1LwMmJjtCj0u4l0SBw@public.gmane.org> writes:
>> 
>> > | The two regressed test cases use __builtin_printf instead of fprintf to
>> > | stderr, but as far as I know, abort is to flush all open streams before
>> > | process termination?
>> 
>> It can't, since abort must be async-signal-safe.
>
> It's still surprising to me that the message written to stderr is lost in
> your aarch64-suse-linux-gnu configuration (only): from a quick look,
> (current) glibc's stdlib/abort.c tries to actually close/flush all open
> streams before process termination.

This is <https://sourceware.org/bugzilla/show_bug.cgi?id=15436>.

Andreas.

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Re: abort might not flush all open streams before process termination (was: aarch64-suse-linux-gnu: libgomp.oacc-c-c++-common/abort-1.c, libgomp.oacc-c-c++-common/abort-3.c FAILs)

[Thomas Schwinge]

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Hi!

On Wed, 7 Oct 2015 12:13:41 +0200, I wrote:
> Copying glibc for your information/in case anyone has any further
> comments, and the man-pages maintainer, Michael Kerrisk.  The issue is
> that abort might not flush all open streams before process termination;
> original thread starting at
> <http://news.gmane.org/find-root.php?message_id=%3C87twq4p9f4.fsf%40kepler.schwinge.homeip.net%3E>.
> 
> On Tue, 06 Oct 2015 13:55:00 +0200, Andreas Schwab <schwab@linux-m68k.org> wrote:
> > Thomas Schwinge <thomas@codesourcery.com> writes:
> > 
> > > | The two regressed test cases use __builtin_printf instead of fprintf to
> > > | stderr, but as far as I know, abort is to flush all open streams before
> > > | process termination?
> > 
> > It can't, since abort must be async-signal-safe.
> 
> It's still surprising to me that the message written to stderr is lost in
> your aarch64-suse-linux-gnu configuration (only): from a quick look,
> (current) glibc's stdlib/abort.c tries to actually close/flush all open
> streams before process termination.

That's <https://sourceware.org/PR15436>, Andreas told us.

> This is also what's documented on
> <http://man7.org/linux/man-pages/man3/abort.3.html>: "all open streams
> are closed and flushed".
> <http://pubs.opengroup.org/onlinepubs/9699919799/functions/abort.html>
> does sound more "conservative": "[abort] may include an attempt to effect
> fclose() on all open streams".  Should the man-page be edited to that
> effect?  And, the following patch be applied to GCC?

I convince myself that the GCC patch was obvious enough; committed in
r229382:

commit 005c2a97673312fa25486a70bd810b9a1b37d367
Author: tschwinge <tschwinge@138bc75d-0d04-0410-961f-82ee72b054a4>
Date:   Mon Oct 26 16:25:04 2015 +0000

    abort might not flush all open streams before process termination
    
    	libgomp/
    	* testsuite/libgomp.oacc-c-c++-common/abort-1.c: Print to stderr.
    	* testsuite/libgomp.oacc-c-c++-common/abort-3.c: Likewise.
    
    git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@229382 138bc75d-0d04-0410-961f-82ee72b054a4
---
 libgomp/ChangeLog                                     | 3 +++
 libgomp/testsuite/libgomp.oacc-c-c++-common/abort-1.c | 3 ++-
 libgomp/testsuite/libgomp.oacc-c-c++-common/abort-3.c | 3 ++-
 3 files changed, 7 insertions(+), 2 deletions(-)

diff --git libgomp/ChangeLog libgomp/ChangeLog
index fa9027b..afc49ae 100644
--- libgomp/ChangeLog
+++ libgomp/ChangeLog
@@ -1,5 +1,8 @@
 2015-10-26  Thomas Schwinge  <thomas@codesourcery.com>
 
+	* testsuite/libgomp.oacc-c-c++-common/abort-1.c: Print to stderr.
+	* testsuite/libgomp.oacc-c-c++-common/abort-3.c: Likewise.
+
 	* testsuite/libgomp.oacc-c-c++-common/lib-1.c: Remove explicit
 	acc_device_nvidia usage.
 	* testsuite/libgomp.oacc-c-c++-common/lib-10.c: Likewise.
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/abort-1.c libgomp/testsuite/libgomp.oacc-c-c++-common/abort-1.c
index 6a9b1df..296708f 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/abort-1.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/abort-1.c
@@ -1,11 +1,12 @@
 /* { dg-do run } */
 
+#include <stdio.h>
 #include <stdlib.h>
 
 int
 main (void)
 {
-  __builtin_printf ("CheCKpOInT\n");
+  fprintf (stderr, "CheCKpOInT\n");
 #pragma acc parallel
   {
     abort ();
diff --git libgomp/testsuite/libgomp.oacc-c-c++-common/abort-3.c libgomp/testsuite/libgomp.oacc-c-c++-common/abort-3.c
index 2c8f347..bca425e 100644
--- libgomp/testsuite/libgomp.oacc-c-c++-common/abort-3.c
+++ libgomp/testsuite/libgomp.oacc-c-c++-common/abort-3.c
@@ -1,11 +1,12 @@
 /* { dg-do run } */
 
+#include <stdio.h>
 #include <stdlib.h>
 
 int
 main (void)
 {
-  __builtin_printf ("CheCKpOInT\n");
+  fprintf (stderr, "CheCKpOInT\n");
 #pragma acc kernels
   {
     abort ();


Grüße
 Thomas

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