[PATCH 18/20] Fix elf/tst-dlmopen-twice to support enough link namespaces

[Florian Weimer]

* Szabolcs Nagy:

> The 10/27/2022 18:24, Florian Weimer wrote:
>> * Szabolcs Nagy via Libc-alpha:
>> 
>> > The test dlmopens 10 namespaces recursively, which requires a glibc
>> > tunable setting, otherwise it may run out of static TLS.
>> > ---
>> >  elf/Makefile            | 1 +
>> >  elf/tst-dlmopen-twice.c | 2 +-
>> >  2 files changed, 2 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/elf/Makefile b/elf/Makefile
>> > index 7b50ccc07a..ace15dc11b 100644
>> > --- a/elf/Makefile
>> > +++ b/elf/Makefile
>> > @@ -2969,6 +2969,7 @@ tst-audit-tlsdesc-ENV = LD_AUDIT=$(objpfx)tst-auditmod-tlsdesc.so
>> >  $(objpfx)tst-audit-tlsdesc-dlopen.out: $(objpfx)tst-auditmod-tlsdesc.so
>> >  tst-audit-tlsdesc-dlopen-ENV = LD_AUDIT=$(objpfx)tst-auditmod-tlsdesc.so
>> >  
>> > +tst-dlmopen-twice-ENV = GLIBC_TUNABLES=glibc.rtld.nns=10
>> >  $(objpfx)tst-dlmopen-twice.out: \
>> >    $(objpfx)tst-dlmopen-twice-mod1.so \
>> >    $(objpfx)tst-dlmopen-twice-mod2.so
>> > diff --git a/elf/tst-dlmopen-twice.c b/elf/tst-dlmopen-twice.c
>> > index 70c71fe19c..dfa58b1505 100644
>> > --- a/elf/tst-dlmopen-twice.c
>> > +++ b/elf/tst-dlmopen-twice.c
>> > @@ -46,7 +46,7 @@ do_test (void)
>> >    recurse (1);
>> >  
>> >    /* Then with nesting.  The constant needs to be less than the
>> > -     internal DL_NNS namespace constant.  */
>> > +     glibc.rtld.nns tunable (which is between 1 and DL_NNS).  */
>> >    recurse (10);
>> >    return 0;
>> >  }
>> 
>> This doesn't work if configured with --disable-tunables.
>> 
>> I suspect this is merely a symptom.  The static TLS sizing defaults
>> should allow creating DL_NNS namespaces?
>
> the tunable defaults to 4, DL_NNS is 16 and that's the max value
> of the tunable (since that's the static namespace array size)

Maybe we should lower the constant from 10 to 3 then?  I mistakenly
assumed the namespace count was higher than it actually is.  3 should
not yet invalidate the test.

Thanks,
Florian