Clean up forking and cloning.

The kernel now maintains the pthread_internal_t::tid field for us,
and __clone was only used in one place so let's inline it so we don't
have to leave such a dangerous function lying around. Also rename
files to match their content and remove some useless #includes.

Change-Id: I24299fb4a940e394de75f864ee36fdabbd9438f9

6 files changed, 32 insertions, 47 deletions

diff --git a/libc/bionic/bionic_clone.c b/libc/bionic/clone.cpp
index 518d99634..1d997fed7 100644
--- a/libc/bionic/bionic_clone.c
+++ b/libc/bionic/clone.cpp
@@ -25,41 +25,39 @@
  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  */
+
 #define __GNU_SOURCE 1
 #include <sched.h>
 #include <stdlib.h>
 #include <stdarg.h>
-#include <stdio.h>
 
-extern pid_t __bionic_clone(uint32_t flags, void* child_stack, int* parent_tid, void* tls, int* child_tid, int (*fn)(void*), void* arg);
-extern void __exit(int status);
+extern "C" pid_t __bionic_clone(uint32_t flags, void* child_stack, int* parent_tid, void* tls, int* child_tid, int (*fn)(void*), void* arg);
+extern "C" void __exit(int status);
 
-/* this function is called from the __bionic_clone
- * assembly fragment to call the thread function
- * then exit. */
-extern void __bionic_clone_entry(int (*fn)(void*), void* arg) {
+// Called from the __bionic_clone assembler to call the thread function then exit.
+extern "C" void __bionic_clone_entry(int (*fn)(void*), void* arg) {
   int status = (*fn)(arg);
   __exit(status);
 }
 
 int clone(int (*fn)(void*), void* child_stack, int flags, void* arg, ...) {
-    va_list  args;
-    int     *parent_tidptr = NULL;
-    void    *new_tls = NULL;
-    int     *child_tidptr = NULL;
+  int* parent_tid = NULL;
+  void* new_tls = NULL;
+  int* child_tid = NULL;
 
-    /* extract optional parameters - they are cumulative. */
-    va_start(args, arg);
-    if (flags & (CLONE_PARENT_SETTID|CLONE_SETTLS|CLONE_CHILD_SETTID)) {
-        parent_tidptr = va_arg(args, int*);
-    }
-    if (flags & (CLONE_SETTLS|CLONE_CHILD_SETTID)) {
-        new_tls = va_arg(args, void*);
-    }
-    if (flags & CLONE_CHILD_SETTID) {
-        child_tidptr = va_arg(args, int*);
-    }
-    va_end(args);
+  // Extract any optional parameters required by the flags.
+  va_list args;
+  va_start(args, arg);
+  if ((flags & (CLONE_PARENT_SETTID|CLONE_SETTLS|CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) {
+    parent_tid = va_arg(args, int*);
+  }
+  if ((flags & (CLONE_SETTLS|CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) {
+    new_tls = va_arg(args, void*);
+  }
+  if ((flags & (CLONE_CHILD_SETTID|CLONE_CHILD_CLEARTID)) != 0) {
+    child_tid = va_arg(args, int*);
+  }
+  va_end(args);
 
-    return __bionic_clone(flags, child_stack, parent_tidptr, new_tls, child_tidptr, fn, arg);
+  return __bionic_clone(flags, child_stack, parent_tid, new_tls, child_tid, fn, arg);
 }
diff --git a/libc/bionic/fork.cpp b/libc/bionic/fork.cpp
index f7d1c11c3..9fa5fcf5f 100644
--- a/libc/bionic/fork.cpp
+++ b/libc/bionic/fork.cpp
@@ -27,11 +27,10 @@
  */
 
 #include <unistd.h>
-#include "pthread_internal.h"
-
-#include "private/bionic_pthread.h"
+#include <sys/syscall.h>
 
-extern "C" int __clone(int, void*, int*, void*, int*);
+#include "private/libc_logging.h"
+#include "pthread_internal.h"
 
 int fork() {
   // POSIX mandates that the timers of a fork child process be
@@ -42,18 +41,17 @@ int fork() {
   __bionic_atfork_run_prepare();
 
   pthread_internal_t* self = __get_thread();
-#if defined(__x86_64__)
-  int result = __clone(CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | SIGCHLD, NULL, NULL, &(self->tid), NULL);
+  int flags = CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | SIGCHLD;
+#if defined(__x86_64__) // sys_clone's last two arguments are flipped on x86-64.
+  int result = syscall(__NR_clone, flags, NULL, NULL, &(self->tid), NULL);
 #else
-  int result = __clone(CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID | SIGCHLD, NULL, NULL, NULL, &(self->tid));
+  int result = syscall(__NR_clone, flags, NULL, NULL, NULL, &(self->tid));
 #endif
-  if (result != 0) {  // Not a child process.
+  if (result == 0) {
+    __bionic_atfork_run_child();
+  } else {
     __timer_table_start_stop(0);
     __bionic_atfork_run_parent();
-  } else {
-    // Fix the tid in the pthread_internal_t struct after a fork.
-    __pthread_settid(pthread_self(), gettid());
-    __bionic_atfork_run_child();
   }
   return result;
 }
diff --git a/libc/bionic/pthread_cond.cpp b/libc/bionic/pthread_cond.cpp
index abd453e8f..7c229b5ec 100644
--- a/libc/bionic/pthread_cond.cpp
+++ b/libc/bionic/pthread_cond.cpp
@@ -38,7 +38,6 @@
 
 #include "private/bionic_atomic_inline.h"
 #include "private/bionic_futex.h"
-#include "private/bionic_pthread.h"
 #include "private/bionic_time_conversions.h"
 #include "private/bionic_tls.h"
 #include "private/thread_private.h"
diff --git a/libc/bionic/pthread_internal.h b/libc/bionic/pthread_internal.h
index de1ef26b9..bcd9b7104 100644
--- a/libc/bionic/pthread_internal.h
+++ b/libc/bionic/pthread_internal.h
@@ -97,6 +97,5 @@ __LIBC_HIDDEN__ extern void __timer_table_start_stop(int);
 __LIBC_HIDDEN__ extern void __bionic_atfork_run_prepare();
 __LIBC_HIDDEN__ extern void __bionic_atfork_run_child();
 __LIBC_HIDDEN__ extern void __bionic_atfork_run_parent();
-__LIBC_HIDDEN__ extern int __pthread_settid(pthread_t, pid_t);
 
 #endif /* _PTHREAD_INTERNAL_H_ */
diff --git a/libc/bionic/pthread_internals.cpp b/libc/bionic/pthread_internals.cpp
index 4b1f6efb9..f8afeaf47 100644
--- a/libc/bionic/pthread_internals.cpp
+++ b/libc/bionic/pthread_internals.cpp
@@ -73,14 +73,6 @@ pid_t __pthread_gettid(pthread_t t) {
   return reinterpret_cast<pthread_internal_t*>(t)->tid;
 }
 
-int __pthread_settid(pthread_t t, pid_t tid) {
-  if (t == 0) {
-    return EINVAL;
-  }
-  reinterpret_cast<pthread_internal_t*>(t)->tid = tid;
-  return 0;
-}
-
 // Initialize 'ts' with the difference between 'abstime' and the current time
 // according to 'clock'. Returns -1 if abstime already expired, or 0 otherwise.
 int __timespec_to_absolute(timespec* ts, const timespec* abstime, clockid_t clock) {
diff --git a/libc/bionic/pthread_mutex.cpp b/libc/bionic/pthread_mutex.cpp
index 7e43cd841..1010f11d4 100644
--- a/libc/bionic/pthread_mutex.cpp
+++ b/libc/bionic/pthread_mutex.cpp
@@ -38,7 +38,6 @@
 
 #include "private/bionic_atomic_inline.h"
 #include "private/bionic_futex.h"
-#include "private/bionic_pthread.h"
 #include "private/bionic_tls.h"
 #include "private/thread_private.h"