glibc: add ld.so locks in _libc_fork

The patch in this Bugzilla entry was requested by a customer:
  https://sourceware.org/bugzilla/show_bug.cgi?id=4578
  https://www.sourceware.org/bugzilla/show_bug.cgi?id=19282

If a thread happens to hold dl_load_lock and have r_state set to RT_ADD or
RT_DELETE at the time another thread calls fork(), then the child exit code
from fork (in nptl/sysdeps/unix/sysv/linux/fork.c in our case) re-initializes
dl_load_lock but does not restore r_state to RT_CONSISTENT. If the child
subsequently requires ld.so functionality before calling exec(), then the
assertion will fire.

The patch acquires dl_load_lock on entry to fork() and releases it on exit
from the parent path.  The child path is initialized as currently done.
This is essentially pthreads_atfork, but forced to be first because the
acquisition of dl_load_lock must happen before malloc_atfork is active
to avoid a deadlock.

The __libc_fork() code reset dl_load_lock, but it also needed to reset
dl_load_write_lock.

(From OE-Core rev: f2e586ebf59a9b7d5b216fc92aeb892069a4b0c1)

Signed-off-by: Zhixiong Chi <zhixiong.chi@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/meta/recipes-core/glibc/glibc_2.26.bb b/meta/recipes-core/glibc/glibc_2.26.bb
index d453d8f9bf..135ec4fb16 100644
--- a/meta/recipes-core/glibc/glibc_2.26.bb
+++ b/meta/recipes-core/glibc/glibc_2.26.bb
@@ -41,6 +41,8 @@ SRC_URI = "${GLIBC_GIT_URI};branch=${SRCBRANCH};name=glibc \
            file://0024-elf-dl-deps.c-Make-_dl_build_local_scope-breadth-fir.patch \
            file://0025-locale-fix-hard-coded-reference-to-gcc-E.patch \
            file://0026-assert-Suppress-pedantic-warning-caused-by-statement.patch \
+           file://0027-glibc-reset-dl-load-write-lock-after-forking.patch \
+           file://0028-Bug-4578-add-ld.so-lock-while-fork.patch \
 "
 
 NATIVESDKFIXES ?= ""