[git commit] LT.old: Make __errno_location/__h_errno_location thread safe

[Bernhard Reutner-Fischer]

commit: http://git.uclibc.org/uClibc/commit/?id=8f550715c2b211036fc273add3cb5219397ed312
branch: http://git.uclibc.org/uClibc/commit/?id=refs/heads/master

WHY: errno in uClibc is not thread safe

HOW: __errno_location and it's sibling __h_errno_location need to be called
     via PLT - even from within libc. That way when linked with pthread,
     intra-uClibc callers will also use the thread safe version.

     This is achieved by removing the GI alias for these functions,
     ensuring that they get called normally (via PLT)

Verified with ARC LT.old and ARM cubieboard2 buildroot (LT.old)
NPTL is unaffected by this bug.

------------ History behind this patch ---------------------

This is a long standing bug (https://bugs.busybox.net/show_bug.cgi?id=2089)

Others have tried to fix it in past (alteast Peter Korsgaard's patch in 2010),
but somehow failed to be merged (or were backed out afterwards).
http://lists.uclibc.org/pipermail/uclibc/2010-July/044176.html

One of the causes could be side effect of atleast one more bug related to
pthreads and static link which has now been fixed.
http://lists.uclibc.org/pipermail/uclibc/2013-October/047958.html

I have solved this w/o looking at other pacthes but would like to give
credit to Peter and others for confirming that it makes sense.

Cc: Christian Ruppert <christian.ruppert at abilis.com>
CC: Francois Bedard <Francois.Bedard at synopsys.com>
Cc: Joern Rennecke  <joern.rennecke at embecosm.com>
Cc: Jeremy Bennett <jeremy.bennett at embecosm.com>
Cc: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
Cc: Peter Korsgaard <peter at korsgaard.com>
Cc: Khem Raj <raj.khem at gmail.com>
Cc: buildroot at busybox.net
Signed-off-by: Vineet Gupta <vgupta at synopsys.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop at gmail.com>
---
 include/netdb.h                          |    3 ---
 libc/misc/internals/__errno_location.c   |    1 -
 libc/misc/internals/__h_errno_location.c |    1 -
 libc/sysdeps/linux/common/bits/errno.h   |    3 ---
 4 files changed, 0 insertions(+), 8 deletions(-)

diff --git a/include/netdb.h b/include/netdb.h
index 8fdfa0f..0f361bb 100644
--- a/include/netdb.h
+++ b/include/netdb.h
@@ -59,11 +59,8 @@ __BEGIN_DECLS
 /* Function to get address of global `h_errno' variable.  */
 extern int *__h_errno_location (void) __THROW __attribute__ ((__const__));
 #ifdef _LIBC
-# if !defined(__UCLIBC_HAS_TLS__) && !defined(__UCLIBC_HAS_THREADS__)
 extern int weak_const_function *__h_errno_location(void);
-# endif
 #endif
-libc_hidden_proto(__h_errno_location)
 
 /* Macros for accessing h_errno from inside libc.  */
 #ifdef _LIBC
diff --git a/libc/misc/internals/__errno_location.c b/libc/misc/internals/__errno_location.c
index be7a909..9bbc2d7 100644
--- a/libc/misc/internals/__errno_location.c
+++ b/libc/misc/internals/__errno_location.c
@@ -16,4 +16,3 @@ int *__errno_location(void)
 {
     return &errno;
 }
-libc_hidden_weak(__errno_location)
diff --git a/libc/misc/internals/__h_errno_location.c b/libc/misc/internals/__h_errno_location.c
index 6653681..b30859e 100644
--- a/libc/misc/internals/__h_errno_location.c
+++ b/libc/misc/internals/__h_errno_location.c
@@ -16,4 +16,3 @@ int *__h_errno_location(void)
 {
     return &h_errno;
 }
-libc_hidden_weak(__h_errno_location)
diff --git a/libc/sysdeps/linux/common/bits/errno.h b/libc/sysdeps/linux/common/bits/errno.h
index 777338f..611b835 100644
--- a/libc/sysdeps/linux/common/bits/errno.h
+++ b/libc/sysdeps/linux/common/bits/errno.h
@@ -43,11 +43,8 @@
 /* Function to get address of global `errno' variable.  */
 extern int *__errno_location (void) __THROW __attribute__ ((__const__));
 #  ifdef _LIBC
-#   if !defined(__UCLIBC_HAS_TLS__) && !defined(__UCLIBC_HAS_THREADS__)
 extern int weak_const_function *__errno_location(void);
-#   endif
 #  endif
-libc_hidden_proto(__errno_location)
 
 #  ifdef __UCLIBC_HAS_THREADS__
 /* When using threads, errno is a per-thread value.  */