mirrors/poky
1
0
Fork 0
mirror of https://git.yoctoproject.org/poky synced 2026-05-08 17:19:20 +00:00
Code Issues Projects Releases Wiki Activity

glibc: add ld.so locks in _libc_fork

Browse Source 
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>
This commit is contained in:
Zhixiong Chi
2017-09-05 12:29:44 +08:00
committed by Richard Purdie
parent f6f6b3e5d5
commit ee9db1a915
3 changed files with 96 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files
meta/recipes-core/glibc/glibc/0027-glibc-reset-dl-load-write-lock-after-forking.patch
+37
View File
@@ -0,0 +1,37 @@
From a6bb73d1cfd20a73fbbe6076008376fb87879d1b Mon Sep 17 00:00:00 2001
From: Yuanjie Huang <yuanjie.huang@windriver.com>
Date: Thu, 18 Aug 2016 17:59:13 +0800
Subject: [PATCH] reset dl_load_write_lock after forking
The patch in this Bugzilla entry was requested by a customer:
https://www.sourceware.org/bugzilla/show_bug.cgi?id=19282
The __libc_fork() code reset dl_load_lock, but it also needed to reset
dl_load_write_lock. The patch has not yet been integrated upstream.
Upstream-Status: Pending [ Not Author See bugzilla]
Signed-off-by: Damodar Sonone <damodar.sonone@kpit.com>
Signed-off-by: Yuanjie Huang <yuanjie.huang@windriver.com>
---
sysdeps/nptl/fork.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/sysdeps/nptl/fork.c b/sysdeps/nptl/fork.c
index 2b9ae4b..3d0b8da 100644
--- a/sysdeps/nptl/fork.c
+++ b/sysdeps/nptl/fork.c
@@ -174,8 +174,9 @@ __libc_fork (void)
/* Reset locks in the I/O code. */
_IO_list_resetlock ();
- /* Reset the lock the dynamic loader uses to protect its data. */
+ /* Reset the locks the dynamic loader uses to protect its data. */
__rtld_lock_initialize (GL(dl_load_lock));
+ __rtld_lock_initialize (GL(dl_load_write_lock));
/* Run the handlers registered for the child. */
while (allp != NULL)
--
1.9.1
meta/recipes-core/glibc/glibc/0028-Bug-4578-add-ld.so-lock-while-fork.patch
+57
View File
@@ -0,0 +1,57 @@
The patch in this Bugzilla entry was requested by a customer:
https://sourceware.org/bugzilla/show_bug.cgi?id=4578
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 patch has not yet been integrated upstream.
Upstream-Status: Pending [ Not Author See bugzilla]
Signed-off-by: Raghunath Lolur <Raghunath.Lolur@kpit.com>
Signed-off-by: Yuanjie Huang <yuanjie.huang@windriver.com>
Signed-off-by: Zhixiong Chi <zhixiong.chi@windriver.com>
Index: git/sysdeps/nptl/fork.c
===================================================================
--- git.orig/sysdeps/nptl/fork.c 2017-08-03 16:02:15.674704080 +0800
+++ git/sysdeps/nptl/fork.c 2017-08-04 18:15:02.463362015 +0800
@@ -25,6 +25,7 @@
#include <tls.h>
#include <hp-timing.h>
#include <ldsodefs.h>
+#include <libc-lock.h>
#include <stdio-lock.h>
#include <atomic.h>
#include <nptl/pthreadP.h>
@@ -60,6 +61,10 @@
but our current fork implementation is not. */
bool multiple_threads = THREAD_GETMEM (THREAD_SELF, header.multiple_threads);
+ /* grab ld.so lock BEFORE switching to malloc_atfork */
+ __rtld_lock_lock_recursive (GL(dl_load_lock));
+ __rtld_lock_lock_recursive (GL(dl_load_write_lock));
+
/* Run all the registered preparation handlers. In reverse order.
While doing this we build up a list of all the entries. */
struct fork_handler *runp;
@@ -247,6 +252,10 @@
allp = allp->next;
}
+
+ /* unlock ld.so last, because we locked it first */
+ __rtld_lock_unlock_recursive (GL(dl_load_write_lock));
+ __rtld_lock_unlock_recursive (GL(dl_load_lock));
}
return pid;
meta/recipes-core/glibc/glibc_2.26.bb
+2
View File
@@ -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 ?= ""