Handle pthread-related changes (mutex/atfork)
First commit:
Revert "Revert "am be741d47: am 2f460fbe: am 73b5cad9: Merge "bionic: Fix wrong kernel_id in pthread descriptor after fork()"""
This reverts commit 06823da2f0c8b4a4ce4c45113032f03df85c94b8.
Second commit:
bionic: fix atfork hanlder_mutex deadlock
This cherry-picks commit 34e89c232dd5645fe3b5f9b40856d8e3e4cae57a
After applying the kernel_id fix, the system refused to boot up and we
got following crash log:
I/DEBUG ( 113): pid: 618, tid: 618 >>> org.simalliance.openmobileapi.service:remote <<<
I/DEBUG ( 113): signal 16 (SIGSTKFLT), code -6 (?), fault addr --------
I/DEBUG ( 113): eax fffffe00 ebx b77de994 ecx 00000080 edx 00724002
I/DEBUG ( 113): esi 00000000 edi 00004000
I/DEBUG ( 113): xcs 00000073 xds 0000007b xes 0000007b xfs 00000000 xss 0000007b
I/DEBUG ( 113): eip b7761351 ebp bfdf3de8 esp bfdf3dc4 flags 00000202
I/DEBUG ( 113): #00 eip: 00015351 /system/lib/libc.so
I/DEBUG ( 113): #01 eip: 0000d13c /system/lib/libc.so (pthread_mutex_lock)
I/DEBUG ( 113): #02 eip: 00077b48 /system/lib/libc.so (__bionic_atfork_run_prepare)
I/DEBUG ( 113): #03 eip: 00052cdb /system/lib/libc.so (fork)
I/DEBUG ( 113): #04 eip: 0009ae91 /system/lib/libdvm.so (_Z18dvmOptimizeDexFileillPKcjjb)
I/DEBUG ( 113): #05 eip: 000819d6 /system/lib/libdvm.so (_Z14dvmJarFileOpenPKcS0_PP7JarFileb)
I/DEBUG ( 113): #06 eip: 000b175e /system/lib/libdvm.so (_ZL40Dalvik_dalvik_system_DexFile_openDexFilePKjP6JValue)
I/DEBUG ( 113): #07 eip: 0011fb94 /system/lib/libdvm.so
Root cause:
The atfork uses the mutex handler_mutex to protect the atfork_head. The
parent will call __bionic_atfork_run_prepare() to lock the handler_mutex,
and need both the parent and child to unlock their own copy of handler_mutex
after fork. At that time, the owner of hanlder_mutex is set as the parent.
If we apply the kernel_id fix, then the child's kernel_id will be set as
child's tid.
The handler_mutex is a recursive lock, and pthread_mutex_unlock(&hander_mutex)
will fail because the mutex owner is the parent, while the current tid
(__get_thread()->kernel_id) is child, not matched with the mutex owner.
At that time, the handler_mutex is left in lock state.If the child wants to
fork other process after than, then it will try to lock handler_mutex, and
then be deadlocked.
Fix:
Since the child has its own copy of vm space from the the parent, the
child space's handler_mutex should be reset to the initialized state.
Change-Id: I3907dd9a153418fb78862f2aa6d0302c375d9e27
Signed-off-by: Jack Ren <jack.ren@intel.com>
Signed-off-by: Chenyang Du <chenyang.du@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
Change-Id: Ic8072f366a877443a60fe215f3c00b3df5a259c8
diff --git a/libc/bionic/fork.c b/libc/bionic/fork.c
index 0eedb01..2d5a10a 100644
--- a/libc/bionic/fork.c
+++ b/libc/bionic/fork.c
@@ -27,6 +27,7 @@
*/
#include <unistd.h>
#include "pthread_internal.h"
+#include "bionic_pthread.h"
#include "cpuacct.h"
extern int __fork(void);
@@ -48,6 +49,9 @@
__timer_table_start_stop(0);
__bionic_atfork_run_parent();
} else {
+ /* Adjusting the kernel id after a fork */
+ (void)__pthread_settid(pthread_self(), gettid());
+
/*
* Newly created process must update cpu accounting.
* Call cpuacct_add passing in our uid, which will take
diff --git a/libc/bionic/pthread-atfork.c b/libc/bionic/pthread-atfork.c
index 3a5189d..42420dc 100644
--- a/libc/bionic/pthread-atfork.c
+++ b/libc/bionic/pthread-atfork.c
@@ -74,6 +74,7 @@
void __bionic_atfork_run_child()
{
struct atfork_t *cursor;
+ pthread_mutexattr_t attr;
/* Call pthread_atfork() child handlers */
for (cursor = atfork_head.cqh_first;
@@ -84,7 +85,9 @@
}
}
- pthread_mutex_unlock(&handler_mutex);
+ pthread_mutexattr_init(&attr);
+ pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
+ pthread_mutex_init(&handler_mutex, &attr);
}
void __bionic_atfork_run_parent()
diff --git a/libc/bionic/pthread.c b/libc/bionic/pthread.c
index d9ca432..fdfe508 100644
--- a/libc/bionic/pthread.c
+++ b/libc/bionic/pthread.c
@@ -2292,3 +2292,14 @@
pthread_internal_t* thread = (pthread_internal_t*)thid;
return thread->kernel_id;
}
+
+int __pthread_settid(pthread_t thid, pid_t tid)
+{
+ if (thid == 0)
+ return EINVAL;
+
+ pthread_internal_t* thread = (pthread_internal_t*)thid;
+ thread->kernel_id = tid;
+
+ return 0;
+}
diff --git a/libc/private/bionic_pthread.h b/libc/private/bionic_pthread.h
index 07bcbd4..28d6ad8 100644
--- a/libc/private/bionic_pthread.h
+++ b/libc/private/bionic_pthread.h
@@ -35,6 +35,7 @@
/* Internal, not an NDK API */
extern pid_t __pthread_gettid(pthread_t thid);
+extern int __pthread_settid(pthread_t thid, pid_t tid);
__END_DECLS