dtrace discuss - Aug 2008 - USDT probes and really long function names (>128 chars)

Hi !

while working with customer on TNF to DTrace conversion I hit an
interesting problem:

It appears that if USDT probe is placed in the function with long name
(more than 128 chars) dtrace -G chops the names to 128 chars in the
resulting objects. The linker then fails to link the executable (quite
expectedly).
For C application I''d say someone who uses function names that long
just deserves that. However, with C++ the mangling easily can grow the
function name to be quite long.

Here is how it looks:

hellride:/export/dev/dte> make CCC=/opt/SUNWspro.12/bin/CC
/opt/SUNWspro.12/bin/CC -m64 -g   -c  dtea.cc
dtrace -C -G -64 -s dte_probes.d dtea.o
/opt/SUNWspro.12/bin/CC -m64 -o dte dtea.o dte_probes.o
Undefined			first referenced
 symbol  			    in file
__1cMprocess_data6FpkCLnZsomewhat_long_class_name1_nZsomewhat_long_class_name2_nZsomewhat_long_class_name3_nZsomewhat_long_clas
dte_probes.o
ld: fatal: Symbol referencing errors. No output written to dte
*** Error code 1
make: Fatal error: Command failed for target `dte''


Is there any easy workaround ? I mean beyond finding[1] the offending
definition and recompiling libdtrace with larger buffer.
Shouldn''t dtrace employ same logic linker uses to process object files
?

[1] Is it this place ?
http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/lib/libdtrace/common/dt_parser.h#172


-- 
Regards,
 Cyril

Hi Cyril,

Unfortunately, there''s no simple work around other than hacking it up
to
incur a shorter function name. Please file a bug and we''ll try to get
that
resolved.

Adam

On Wed, Aug 06, 2008 at 11:00:11PM +0300, Cyril Plisko
wrote:
> Hi !
> 
> while working with customer on TNF to DTrace conversion I hit an
> interesting problem:
> 
> It appears that if USDT probe is placed in the function with long name
> (more than 128 chars) dtrace -G chops the names to 128 chars in the
> resulting objects. The linker then fails to link the executable (quite
> expectedly).
> For C application I''d say someone who uses function names that
long
> just deserves that. However, with C++ the mangling easily can grow the
> function name to be quite long.
> 
> Here is how it looks:
> 
> hellride:/export/dev/dte> make CCC=/opt/SUNWspro.12/bin/CC
> /opt/SUNWspro.12/bin/CC -m64 -g   -c  dtea.cc
> dtrace -C -G -64 -s dte_probes.d dtea.o
> /opt/SUNWspro.12/bin/CC -m64 -o dte dtea.o dte_probes.o
> Undefined			first referenced
>  symbol  			    in file
>
__1cMprocess_data6FpkCLnZsomewhat_long_class_name1_nZsomewhat_long_class_name2_nZsomewhat_long_class_name3_nZsomewhat_long_clas
> dte_probes.o
> ld: fatal: Symbol referencing errors. No output written to dte
> *** Error code 1
> make: Fatal error: Command failed for target `dte''
> 
> 
> Is there any easy workaround ? I mean beyond finding[1] the offending
> definition and recompiling libdtrace with larger buffer.
> Shouldn''t dtrace employ same logic linker uses to process object
files ?
> 
> [1] Is it this place ?
>
http://src.opensolaris.org/source/xref/onnv/onnv-gate/usr/src/lib/libdtrace/common/dt_parser.h#172
> 
> 
> -- 
> Regards,
>  Cyril
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris.org
-- 
Adam Leventhal, Fishworks                     http://blogs.sun.com/ahl

Hi Adam, 

Do you know if there has been any progress on this?  I don''t see a bug
to reference to track it down ..

Thanks.
Michael
-- 
This message posted from opensolaris.org

> Do you know if there has been any progress on this?  I don''t see a
> bug to reference to track it down ..

Hey Michael,

I don''t see a bug on this either. Would you mind filing it so that it
doesn''t fall off my radar again? Thanks.

Adam

--
Adam Leventhal, Fishworks                        http://blogs.sun.com/ahl

Adam,

I think this is CR# 6258412 "DTrace needs to support longer function
names."  BTW, we ran into this recently when adding probes to MySQL,
so it would be great to get this fixed.

Thanks,
David

----- Original Message -----
From: Adam Leventhal <ahl at eng.sun.com>
Date: Monday, February 23, 2009 2:45 pm
> >Do you know if there has been any progress on this?  I don''t
see a
> bug to reference to track it down ..
> 
> 
> Hey Michael,
> 
> I don''t see a bug on this either. Would you mind filing it so that
it
> doesn''t fall off my radar again? Thanks.
> 
> Adam
> 
> --
> Adam Leventhal, Fishworks                        http://blogs.sun.com/ahl
>

Hey David,

Thanks for finding that. I''m moving the bug into the accepted state so
it
should show up externally in a little while.

Adam

On Tue, Feb 24, 2009 at 08:45:46AM -0800, David Lutz
wrote:
> Adam,
> 
> I think this is CR# 6258412 "DTrace needs to support longer function
> names."  BTW, we ran into this recently when adding probes to MySQL,
> so it would be great to get this fixed.
> 
> Thanks,
> David
> 
> ----- Original Message -----
> From: Adam Leventhal <ahl at eng.sun.com>
> Date: Monday, February 23, 2009 2:45 pm
> 
> > >Do you know if there has been any progress on this?  I
don''t see a
> > bug to reference to track it down ..
> > 
> > 
> > Hey Michael,
> > 
> > I don''t see a bug on this either. Would you mind filing it so
that it
> > doesn''t fall off my radar again? Thanks.
> > 
> > Adam
> > 
> > --
> > Adam Leventhal, Fishworks                       
http://blogs.sun.com/ahl
> > 
> 
-- 
Adam Leventhal, Fishworks                     http://blogs.sun.com/ahl