[PULL 0/1] Tracing patches

[PULL 0/1] Tracing patches

[Stefan Hajnoczi]

The following changes since commit 7623b5ba017f61de5d7c2bba12c6feb3d55091b1:

  Merge remote-tracking branch 'remotes/vivier2/tags/linux-user-for-5.1-pull-request' into staging (2020-07-06 11:40:10 +0100)

are available in the Git repository at:

  https://github.com/stefanha/qemu.git tags/tracing-pull-request

for you to fetch changes up to 27e08bab94f7c6ebe0b75938c98c394c969e3fd8:

  tracetool: work around ust <sys/sdt.h> include conflict (2020-07-07 16:07:14 +0100)

----------------------------------------------------------------
Pull request

Fix for a LTTng Userspace Tracer header problem.

----------------------------------------------------------------

Stefan Hajnoczi (1):
  tracetool: work around ust <sys/sdt.h> include conflict

 scripts/tracetool/backend/dtrace.py | 6 ++++++
 1 file changed, 6 insertions(+)

-- 
2.26.2

[PULL 1/1] tracetool: work around ust <sys/sdt.h> include conflict

[Stefan Hajnoczi]

Both the dtrace and ust backends may include <sys/sdt.h> but LTTng
Userspace Tracer 2.11 and later requires SDT_USE_VARIADIC to be defined
before including the header file.

This is a classic problem with C header files included from different
parts of a program. If the same header is included twice within the same
compilation unit then the first inclusion determines the macro
environment.

Work around this by defining SDT_USE_VARIADIC in the dtrace backend too.
It doesn't hurt and fixes a missing STAP_PROBEV() compiler error when
the ust backend is enabled together with the dtrace backend.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 20200625140757.237012-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 scripts/tracetool/backend/dtrace.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/scripts/tracetool/backend/dtrace.py b/scripts/tracetool/backend/dtrace.py
index 5711892ba0..b7fe4c1b50 100644
--- a/scripts/tracetool/backend/dtrace.py
+++ b/scripts/tracetool/backend/dtrace.py
@@ -40,6 +40,12 @@ def generate_h_begin(events, group):
     else:
         header = "trace-dtrace.h"
 
+    # Workaround for ust backend, which also includes <sys/sdt.h> and may
+    # require SDT_USE_VARIADIC to be defined. If dtrace includes <sys/sdt.h>
+    # first without defining SDT_USE_VARIADIC then ust breaks because the
+    # STAP_PROBEV() macro is not defined.
+    out('#define SDT_USE_VARIADIC 1')
+
     out('#include "%s"' % header,
         '')
 
-- 
2.26.2

Re: [PULL 0/1] Tracing patches

[Peter Maydell]

On Tue, 7 Jul 2020 at 16:20, Stefan Hajnoczi <stefanha@redhat.com> wrote:
>
> The following changes since commit 7623b5ba017f61de5d7c2bba12c6feb3d55091b1:
>
>   Merge remote-tracking branch 'remotes/vivier2/tags/linux-user-for-5.1-pull-request' into staging (2020-07-06 11:40:10 +0100)
>
> are available in the Git repository at:
>
>   https://github.com/stefanha/qemu.git tags/tracing-pull-request
>
> for you to fetch changes up to 27e08bab94f7c6ebe0b75938c98c394c969e3fd8:
>
>   tracetool: work around ust <sys/sdt.h> include conflict (2020-07-07 16:07:14 +0100)
>
> ----------------------------------------------------------------
> Pull request
>
> Fix for a LTTng Userspace Tracer header problem.
>
> ----------------------------------------------------------------
>
> Stefan Hajnoczi (1):
>   tracetool: work around ust <sys/sdt.h> include conflict
>
>  scripts/tracetool/backend/dtrace.py | 6 ++++++
>  1 file changed, 6 insertions(+)


Applied, thanks.

Please update the changelog at https://wiki.qemu.org/ChangeLog/5.1
for any user-visible changes.

-- PMM