Re: [PATCH] elf: Remove dead l_need_tls_init static-TLS init path

[Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>]

On 09/06/26 11:13, Florian Weimer wrote:
> * Adhemerval Zanella:
> 
>> @@ -671,16 +641,18 @@ dl_open_worker_begin (void *a)
>>    if (mode & RTLD_GLOBAL)
>>      add_to_global_resize (new);
>>  
>> -  /* Install the new modules in the DTV slotinfo and initialise their
>> -     static TLS *before* relocation, so an IFUNC resolver firing during
>> -     the relocation loop below can reach its DSO's __thread storage via
>> -     __tls_get_addr / TLSDESC.  Without this, the resolver's TLS access
>> -     for a just-loaded module would index into an unallocated DTV slot
>> -     and crash.  If relocation later fails, the subsequent _dl_close_worker
>> -     cleans up these slotinfo entries via remove_slotinfo.  */
>> +  /* Register the new modules in the DTV slotinfo and bump the TLS
>> +     generation counter *before* relocation, so an IFUNC resolver firing
>> +     during the relocation loop below can reach its DSO's __thread storage
>> +     via __tls_get_addr / TLSDESC.  Without this, the new module is not yet
>> +     in GL(dl_tls_dtv_slotinfo_list), so the resolver's dynamic-TLS lookup
>> +     fails to find it and faults.  The static-TLS image itself is copied
>> +     lazily on first access; for the initial-exec model the static-TLS
>> +     offset is reserved inline during relocation (see
>> +     _dl_try_allocate_static_tls), not here.  If relocation later fails,
>> +     the subsequent _dl_close_worker cleans up these slotinfo entries via
>> +     remove_slotinfo.  */
>>    if (any_tls)
>> -    /* FIXME: This calls _dl_update_slotinfo, which aborts the process
>> -       on memory allocation failure.  See bug 16134.  */
>>      update_tls_slotinfo (new);
> 
> Is the FIXME truly gone?
No, BZ 16134 is not fixed, only relocated. That lazy path still aborts:
  
  __tls_get_addr -> _dl_update_slotinfo -> _dl_resize_dtv -> oom

Per:

elf/dt-tls.c

 921                   /* Resizing the dtv aborts on failure: bug 16134.  */
 922                   dtv = _dl_resize_dtv (dtv, max_modid, THREAD_SELF);