Re: [LTP] fork05 test case fails due to optimization

[Subrata M. <su...@li...>]

Thanks.

Regards--
Subrata

On Wed, 2009-04-15 at 23:36 +0800, CAI Qian wrote:
> From: Subrata Modak <su...@li...>
> Subject: Re: [LTP] fork05 test case fails due to optimization
> Date: Mon, 13 Apr 2009 19:37:23 +0530
> 
> > On Sun, 2009-04-12 at 13:37 +0800, CAI Qian wrote:
> >> From: CAI Qian <ca...@cc...>
> >> Subject: Re: [LTP] fork05 test case fails due to optimization
> >> Date: Sat, 11 Apr 2009 04:02:41 -0700 (PDT)
> >> 
> >> > 
> >> > 
> >> > 
> >> > --- On Tue, 4/7/09, rohit verma <roh...@gm...> wrote:
> >> > 
> >> >> From: rohit verma <roh...@gm...>
> >> >> Subject: [LTP] fork05 test case fails due to optimization
> >> >> To: ltp...@li...
> >> >> Date: Tuesday, April 7, 2009, 5:57 PM
> >> >> There is a change in compilation
> >> >> mechanism in LTP from Feb 09
> >> >> distribution.The previous Make mechanism did not provide
> >> >> any
> >> >> optimization while compiling the fork05 test program and
> >> >> the test used
> >> >> to Pass . However the newer Makefile uses optimization
> >> >> level 2 while
> >> >> compiling, if this file is executed the test case fails ..
> >> >> 
> >> > 
> >> > This is definitely a case. I can reproduce it on Fedora 10, so I have
> >> > created a bug of it, and copied the author Ulrich Drepper,
> >> > 
> >> > https://bugzilla.redhat.com/show_bug.cgi?id=495296
> >> >
> >> 
> >> Ulrich Drepper has pointed out in the above bug report that this failure
> >> was due to incorrect test code.
> >> 
> >>   The test code isn't correct.  The compiler cannot look inside the asm
> >>   statements in main() and see that they are really necessary.  Based on
> >>   the information given the compiler can drop some of them.
> >> 
> >>   Change all asms in main from
> >> 
> >>     asm(...)
> >> 
> >>   to
> >> 
> >>     asm volatile(...)
> >> 
> >>   and the code works fine.
> >> 
> >> With the following patch, it works fine with and without compilation
> >> optimization.
> >> 
> >> Signed-off-by: CAI Qian <ca...@cc...>
> > 
> > Thanks for the fix. But doesn´t apply for me :-)
> > 
> > patching file testcases/kernel/syscalls/fork/fork05.c
> > Hunk #1 FAILED at 178.
> > 1 out of 1 hunk FAILED -- saving rejects to file
> > testcases/kernel/syscalls/fork/fork05.c.rej
> > 
> > Regards--
> > Subrata
> >
> 
> Please try to new patch.
> 
> --- testcases/kernel/syscalls/fork/fork05.c.orig	2009-04-12 13:24:48.000000000 +0800
> +++ testcases/kernel/syscalls/fork/fork05.c	2009-04-12 13:26:28.000000000 +0800
> @@ -178,23 +178,23 @@
>  
>    modify_ldt (1, &ldt0, sizeof (ldt0));
>  
> -  asm ("movw %w0, %%fs" : : "q" (7));
> +  asm volatile ("movw %w0, %%fs" : : "q" (7));
>  
> -  asm ("movl %%fs:0, %0" : "=r" (lo));
> +  asm volatile ("movl %%fs:0, %0" : "=r" (lo));
>    tst_resm(TINFO,"a = %d", lo);
>  
> -  asm ("pushl %%fs; popl %0" : "=q" (lo));
> +  asm volatile ("pushl %%fs; popl %0" : "=q" (lo));
>    tst_resm(TINFO,"%%fs = %#06hx", lo);
>  
> -  asm ("movl %0, %%fs:0" : : "r" (99));
> +  asm volatile ("movl %0, %%fs:0" : : "r" (99));
>  
>    pid = fork ();
>  
>    if (pid == 0) {
> -      asm ("pushl %%fs; popl %0" : "=q" (lo));
> +      asm volatile ("pushl %%fs; popl %0" : "=q" (lo));
>        tst_resm(TINFO,"%%fs = %#06hx", lo);
>  
> -      asm ("movl %%fs:0, %0" : "=r" (lo));
> +      asm volatile ("movl %%fs:0, %0" : "=r" (lo));
>        tst_resm(TINFO,"a = %d", lo);
>  
>        if (lo != 99)
> 
>  
> >> 
> >> --- ltp/testcases/kernel/syscalls/fork/fork05.c.orig	2009-04-12 13:24:48.000000000 +0800
> >> +++ ltp/testcases/kernel/syscalls/fork/fork05.c	2009-04-12 13:26:28.000000000 +0800
> >> @@ -178,23 +178,23 @@
> >>  
> >>    modify_ldt (1, &ldt0, sizeof (ldt0));
> >>  
> >> -  asm ("movw %w0, %%fs" : : "q" (7));
> >> +  asm volatile ("movw %w0, %%fs" : : "q" (7));
> >>  
> >> -  asm ("movl %%fs:0, %0" : "=r" (lo));
> >> +  asm volatile ("movl %%fs:0, %0" : "=r" (lo));
> >>    tst_resm(TINFO,"a = %d", lo);
> >>  
> >> -  asm ("pushl %%fs; popl %0" : "=q" (lo));
> >> +  asm volatile ("pushl %%fs; popl %0" : "=q" (lo));
> >>    tst_resm(TINFO,"%%fs = %#06hx", lo);
> >>  
> >> -  asm ("movl %0, %%fs:0" : : "r" (99));
> >> +  asm volatile ("movl %0, %%fs:0" : : "r" (99));
> >>  
> >>    pid = fork ();
> >>  
> >>    if (pid == 0) {
> >> -      asm ("pushl %%fs; popl %0" : "=q" (lo));
> >> +      asm volatile ("pushl %%fs; popl %0" : "=q" (lo));
> >>        tst_resm(TINFO,"%%fs = %#06hx", lo);
> >>  
> >> -      asm ("movl %%fs:0, %0" : "=r" (lo));
> >> +      asm volatile ("movl %%fs:0, %0" : "=r" (lo));
> >>        tst_resm(TINFO,"a = %d", lo);
> >>  
> >>        if (lo != 99)
> >> 
> >>  
> >> > CAI Qian
> >> > 
> >> >> With Older Make mechanism
> >> >> cc -Wall  -I../../include -g -Wall
> >> >> -I../../../../include -Wall
> >> >> fork05.c  -L../../../../lib -lltp -o fork05
> >> >> 
> >> >> With Newer Make mechanism
> >> >> gcc -g -O2 -I../../include -g -Wall -I../../../../include
> >> >> -Wall
> >> >> fork05.c  -L../../../../lib -lltp -o fork05
> >> >> 
> >> >> Note: If we compile the program in the same
> >> >> directory(/testcases/kernel/syscalls/fork) ,the
> >> >> optimization flag do
> >> >> not come into picture and the test case passes. The
> >> >> optimization is
> >> >> set by some top level Makefile
> >> >> 
> >> >> Regards,
> >> >> Rohit
> >> >> 
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> >> > 
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