debuggerd_handler: actually wait for pseudothread to exit. am: b64dd85c94
am: f47ca0f2d5
Change-Id: Id595ddaaf492c3c97affc528e03e8f4ddc6176c7
diff --git a/debuggerd/handler/debuggerd_handler.cpp b/debuggerd/handler/debuggerd_handler.cpp
index 6033a6b..83db3a7 100644
--- a/debuggerd/handler/debuggerd_handler.cpp
+++ b/debuggerd/handler/debuggerd_handler.cpp
@@ -31,6 +31,7 @@
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
+#include <linux/futex.h>
#include <pthread.h>
#include <sched.h>
#include <signal.h>
@@ -46,6 +47,7 @@
#include <sys/wait.h>
#include <unistd.h>
+#include "private/bionic_futex.h"
#include "private/libc_logging.h"
// see man(2) prctl, specifically the section about PR_GET_NAME
@@ -151,7 +153,6 @@
}
struct debugger_thread_info {
- pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
bool crash_dump_started = false;
pid_t crashing_tid;
pid_t pseudothread_tid;
@@ -228,7 +229,7 @@
}
}
- pthread_mutex_unlock(&thread_info->mutex);
+ syscall(__NR_exit, 0);
return 0;
}
@@ -267,23 +268,26 @@
}
debugger_thread_info thread_info = {
+ .pseudothread_tid = -1,
.crashing_tid = gettid(),
.signal_number = signal_number,
.info = info
};
- pthread_mutex_lock(&thread_info.mutex);
// Essentially pthread_create without CLONE_FILES (see debuggerd_dispatch_pseudothread).
- pid_t child_pid = clone(debuggerd_dispatch_pseudothread, pseudothread_stack,
- CLONE_THREAD | CLONE_SIGHAND | CLONE_VM | CLONE_CHILD_SETTID,
- &thread_info, nullptr, nullptr, &thread_info.pseudothread_tid);
+ pid_t child_pid =
+ clone(debuggerd_dispatch_pseudothread, pseudothread_stack,
+ CLONE_THREAD | CLONE_SIGHAND | CLONE_VM | CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID,
+ &thread_info, nullptr, nullptr, &thread_info.pseudothread_tid);
if (child_pid == -1) {
fatal("failed to spawn debuggerd dispatch thread: %s", strerror(errno));
}
- // Wait for the child to finish and unlock the mutex.
- // This relies on bionic behavior that isn't guaranteed by the standard.
- pthread_mutex_lock(&thread_info.mutex);
+ // Wait for the child to start...
+ __futex_wait(&thread_info.pseudothread_tid, -1, nullptr);
+
+ // and then wait for it to finish.
+ __futex_wait(&thread_info.pseudothread_tid, child_pid, nullptr);
// Signals can either be fatal or nonfatal.
// For fatal signals, crash_dump will PTRACE_CONT us with the signal we