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

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

Since af34b1376a3 ("elf: Initialize static TLS before relocation
processing", BZ 34164) dropped the 'defer-if-not-relocated' branch in
_dl_try_allocate_static_tls, nothing sets l_need_tls_init any more.  The
second pass in update_tls_slotinfo, guarded by l_need_tls_init, is
therefore dead: its _dl_update_slotinfo / _dl_init_static_tls calls never
run, and the static TLS image is initialised inline during relocation (IE
model) or lazily on first dynamic-TLS access instead.

Remove the dead loop, the now write-only l_need_tls_init field and its
clear in _dl_allocate_tls_init.  No functional change.

Checked on aarch64-linux-gnu, x86_64-linux-gnu, and i686-linux-gnu.
I also run the elf tests on armv7-a, alpha, loongarch64, mips64le,
powerpc, riscv, and s390x using qemu system.
---
 elf/dl-open.c  | 50 +++++++++++---------------------------------------
 elf/dl-tls.c   |  9 +++------
 include/link.h |  3 ---
 3 files changed, 14 insertions(+), 48 deletions(-)

diff --git a/elf/dl-open.c b/elf/dl-open.c
index cf4749694f9..ba06e837bae 100644
--- a/elf/dl-open.c
+++ b/elf/dl-open.c
@@ -382,36 +382,6 @@ update_tls_slotinfo (struct link_map *new)
 TLS generation counter wrapped!  Please report this."));
   /* Can be read concurrently.  */
   atomic_store_release (&GL(dl_tls_generation), newgen);
-
-  /* We need a second pass for static tls data, because
-     _dl_update_slotinfo must not be run while calls to
-     _dl_add_to_slotinfo are still pending.  */
-  for (unsigned int i = 0; i < new->l_searchlist.r_nlist; ++i)
-    {
-      struct link_map *imap = new->l_searchlist.r_list[i];
-
-      if (imap->l_need_tls_init && imap->l_tls_blocksize > 0)
-	{
-	  /* For static TLS we have to allocate the memory here and
-	     now, but we can delay updating the DTV.  */
-	  imap->l_need_tls_init = 0;
-#ifdef SHARED
-	  /* Update the slot information data for the current
-	     generation.  */
-
-	  /* FIXME: This can terminate the process on memory
-	     allocation failure.  It is not possible to raise
-	     exceptions from this context; to fix this bug,
-	     _dl_update_slotinfo would have to be split into two
-	     operations, similar to resize_scopes and update_scopes
-	     above.  This is related to bug 16134.  */
-	  _dl_update_slotinfo (imap->l_tls_modid, newgen);
-#endif
-
-	  _dl_init_static_tls (imap);
-	  assert (imap->l_need_tls_init == 0);
-	}
-    }
 }
 
 /* Mark the objects as NODELETE if required.  This is delayed until
@@ -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);
 
   /* Perform relocation.  This can trigger lazy binding in IFUNC
diff --git a/elf/dl-tls.c b/elf/dl-tls.c
index 1380bd70831..f2a99e8edb5 100644
--- a/elf/dl-tls.c
+++ b/elf/dl-tls.c
@@ -697,17 +697,14 @@ _dl_allocate_tls_init (void *result, bool main_thread)
 	     For audit modules or dependencies with initial-exec TLS,
 	     we can not set the initial TLS image on default loader
 	     initialization because it would already be set by the
-	     audit setup, which uses the dlopen code and already
-	     clears l_need_tls_init.  Calls with !main_thread from
-	     pthread_create need to initialize TLS for the current
-	     thread regardless of namespace.  */
+	     audit setup, which uses the dlopen code.  Calls with
+	     !main_thread from pthread_create need to initialize TLS
+	     for the current thread regardless of namespace.  */
 	  if (map->l_ns != LM_ID_BASE && main_thread)
 	    continue;
 	  memset (__mempcpy (dest, map->l_tls_initimage,
 			     map->l_tls_initimage_size), '\0',
 		  map->l_tls_blocksize - map->l_tls_initimage_size);
-	  if (main_thread)
-	    map->l_need_tls_init = 0;
 	}
 
       total += cnt;
diff --git a/include/link.h b/include/link.h
index 8f851d2212d..e299ca35fd4 100644
--- a/include/link.h
+++ b/include/link.h
@@ -194,9 +194,6 @@ struct link_map
 				      the l_libname list.  */
     unsigned int l_faked:1;	/* Nonzero if this is a faked descriptor
 				   without associated file.  */
-    unsigned int l_need_tls_init:1; /* Nonzero if GL(dl_init_static_tls)
-				       should be called on this link map
-				       when relocation finishes.  */
     unsigned int l_auditing:1;	/* Nonzero if the DSO is used in auditing.  */
     unsigned int l_audit_any_plt:1; /* Nonzero if at least one audit module
 				       is interested in the PLT interception.*/
-- 
2.43.0