Fix debuggerd issues.
- Fix a problem where a tid exits before the attach completes, and it
causes debuggerd to self terminate.
- Fix a problem where sibling tid dumps do not properly wait for the tid
to get signalled.
Bug: 17800180
Bug: 12567315
(cherry picked from commit 84ddb34a3af77dbe490aaa07b738bbfd7109d5ba)
Change-Id: I45e33865614d4c96f4a89cf117398666b556d500
diff --git a/debuggerd/backtrace.cpp b/debuggerd/backtrace.cpp
index c4a2143..e7919e9 100644
--- a/debuggerd/backtrace.cpp
+++ b/debuggerd/backtrace.cpp
@@ -88,7 +88,9 @@
return;
}
- wait_for_stop(tid, total_sleep_time_usec);
+ if (!attached && wait_for_sigstop(tid, total_sleep_time_usec, detach_failed) == -1) {
+ return;
+ }
UniquePtr<Backtrace> backtrace(Backtrace::Create(tid, BACKTRACE_CURRENT_THREAD));
if (backtrace->Unwind(0)) {
diff --git a/debuggerd/debuggerd.cpp b/debuggerd/debuggerd.cpp
index 03d7e49..318b224 100644
--- a/debuggerd/debuggerd.cpp
+++ b/debuggerd/debuggerd.cpp
@@ -79,7 +79,7 @@
"*\n"
"* Wait for gdb to start, then press the VOLUME DOWN key\n"
"* to let the process continue crashing.\n"
- "********************************************************\n",
+ "********************************************************",
request.pid, exe, request.tid);
// Wait for VOLUME DOWN.
@@ -178,11 +178,11 @@
socklen_t len = sizeof(cr);
int status = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &cr, &len);
if (status != 0) {
- ALOGE("cannot get credentials\n");
+ ALOGE("cannot get credentials");
return -1;
}
- ALOGV("reading tid\n");
+ ALOGV("reading tid");
fcntl(fd, F_SETFL, O_NONBLOCK);
pollfd pollfds[1];
@@ -279,6 +279,7 @@
ALOGE("ptrace attach failed: %s\n", strerror(errno));
} else {
bool detach_failed = false;
+ bool tid_unresponsive = false;
bool attach_gdb = should_attach_gdb(&request);
if (TEMP_FAILURE_RETRY(write(fd, "\0", 1)) != 1) {
ALOGE("failed responding to client: %s\n", strerror(errno));
@@ -292,8 +293,9 @@
int total_sleep_time_usec = 0;
for (;;) {
- int signal = wait_for_signal(request.tid, &total_sleep_time_usec);
- if (signal < 0) {
+ int signal = wait_for_sigstop(request.tid, &total_sleep_time_usec, &detach_failed);
+ if (signal == -1) {
+ tid_unresponsive = true;
break;
}
@@ -360,27 +362,21 @@
free(tombstone_path);
}
- ALOGV("detaching\n");
- if (attach_gdb) {
- // stop the process so we can debug
- kill(request.pid, SIGSTOP);
-
- // detach so we can attach gdbserver
- if (ptrace(PTRACE_DETACH, request.tid, 0, 0)) {
- ALOGE("ptrace detach from %d failed: %s\n", request.tid, strerror(errno));
- detach_failed = true;
+ if (!tid_unresponsive) {
+ ALOGV("detaching");
+ if (attach_gdb) {
+ // stop the process so we can debug
+ kill(request.pid, SIGSTOP);
}
-
- // if debug.db.uid is set, its value indicates if we should wait
- // for user action for the crashing process.
- // in this case, we log a message and turn the debug LED on
- // waiting for a gdb connection (for instance)
- wait_for_user_action(request);
- } else {
- // just detach
if (ptrace(PTRACE_DETACH, request.tid, 0, 0)) {
- ALOGE("ptrace detach from %d failed: %s\n", request.tid, strerror(errno));
+ ALOGE("ptrace detach from %d failed: %s", request.tid, strerror(errno));
detach_failed = true;
+ } else if (attach_gdb) {
+ // if debug.db.uid is set, its value indicates if we should wait
+ // for user action for the crashing process.
+ // in this case, we log a message and turn the debug LED on
+ // waiting for a gdb connection (for instance)
+ wait_for_user_action(request);
}
}
diff --git a/debuggerd/tombstone.cpp b/debuggerd/tombstone.cpp
index 32f0eca..5b111ab 100755
--- a/debuggerd/tombstone.cpp
+++ b/debuggerd/tombstone.cpp
@@ -374,11 +374,7 @@
}
}
-static void dump_thread(
- Backtrace* backtrace, log_t* log, int* total_sleep_time_usec) {
-
- wait_for_stop(backtrace->Tid(), total_sleep_time_usec);
-
+static void dump_thread(Backtrace* backtrace, log_t* log) {
dump_registers(log, backtrace->Tid());
dump_backtrace_and_stack(backtrace, log);
@@ -421,13 +417,17 @@
continue;
}
+ if (wait_for_sigstop(new_tid, total_sleep_time_usec, &detach_failed) == -1) {
+ continue;
+ }
+
log->current_tid = new_tid;
_LOG(log, logtype::THREAD, "--- --- --- --- --- --- --- --- --- --- --- --- --- --- --- ---\n");
dump_thread_info(log, pid, new_tid);
UniquePtr<Backtrace> backtrace(Backtrace::Create(pid, new_tid, map));
if (backtrace->Unwind(0)) {
- dump_thread(backtrace.get(), log, total_sleep_time_usec);
+ dump_thread(backtrace.get(), log);
}
log->current_tid = log->crashed_tid;
@@ -628,7 +628,7 @@
UniquePtr<Backtrace> backtrace(Backtrace::Create(pid, tid, map.get()));
if (backtrace->Unwind(0)) {
dump_abort_message(backtrace.get(), log, abort_msg_address);
- dump_thread(backtrace.get(), log, total_sleep_time_usec);
+ dump_thread(backtrace.get(), log);
}
if (want_logs) {
diff --git a/debuggerd/utility.cpp b/debuggerd/utility.cpp
index 9a30fe3..2baf9de 100644
--- a/debuggerd/utility.cpp
+++ b/debuggerd/utility.cpp
@@ -28,8 +28,8 @@
#include <backtrace/Backtrace.h>
#include <log/log.h>
-const int sleep_time_usec = 50000; // 0.05 seconds
-const int max_total_sleep_usec = 10000000; // 10 seconds
+const int SLEEP_TIME_USEC = 50000; // 0.05 seconds
+const int MAX_TOTAL_SLEEP_USEC = 10000000; // 10 seconds
static int write_to_am(int fd, const char* buf, int len) {
int to_write = len;
@@ -91,48 +91,44 @@
}
}
-int wait_for_signal(pid_t tid, int* total_sleep_time_usec) {
+int wait_for_sigstop(pid_t tid, int* total_sleep_time_usec, bool* detach_failed) {
+ bool allow_dead_tid = false;
for (;;) {
int status;
- pid_t n = waitpid(tid, &status, __WALL | WNOHANG);
- if (n < 0) {
- if (errno == EAGAIN)
- continue;
- ALOGE("waitpid failed: %s\n", strerror(errno));
- return -1;
- } else if (n > 0) {
- ALOGV("waitpid: n=%d status=%08x\n", n, status);
+ pid_t n = TEMP_FAILURE_RETRY(waitpid(tid, &status, __WALL | WNOHANG));
+ if (n == -1) {
+ ALOGE("waitpid failed: tid %d, %s", tid, strerror(errno));
+ break;
+ } else if (n == tid) {
if (WIFSTOPPED(status)) {
return WSTOPSIG(status);
} else {
ALOGE("unexpected waitpid response: n=%d, status=%08x\n", n, status);
- return -1;
+ // This is the only circumstance under which we can allow a detach
+ // to fail with ESRCH, which indicates the tid has exited.
+ allow_dead_tid = true;
+ break;
}
}
- if (*total_sleep_time_usec > max_total_sleep_usec) {
- ALOGE("timed out waiting for tid=%d to die\n", tid);
- return -1;
- }
-
- // not ready yet
- ALOGV("not ready yet\n");
- usleep(sleep_time_usec);
- *total_sleep_time_usec += sleep_time_usec;
- }
-}
-
-void wait_for_stop(pid_t tid, int* total_sleep_time_usec) {
- siginfo_t si;
- while (TEMP_FAILURE_RETRY(ptrace(PTRACE_GETSIGINFO, tid, 0, &si)) < 0 && errno == ESRCH) {
- if (*total_sleep_time_usec > max_total_sleep_usec) {
- ALOGE("timed out waiting for tid=%d to stop\n", tid);
+ if (*total_sleep_time_usec > MAX_TOTAL_SLEEP_USEC) {
+ ALOGE("timed out waiting for stop signal: tid=%d", tid);
break;
}
- usleep(sleep_time_usec);
- *total_sleep_time_usec += sleep_time_usec;
+ usleep(SLEEP_TIME_USEC);
+ *total_sleep_time_usec += SLEEP_TIME_USEC;
}
+
+ if (ptrace(PTRACE_DETACH, tid, 0, 0) != 0) {
+ if (allow_dead_tid && errno == ESRCH) {
+ ALOGE("tid exited before attach completed: tid %d", tid);
+ } else {
+ *detach_failed = true;
+ ALOGE("detach failed: tid %d, %s", tid, strerror(errno));
+ }
+ }
+ return -1;
}
#if defined (__mips__)
diff --git a/debuggerd/utility.h b/debuggerd/utility.h
index 82413b8..58a882c 100644
--- a/debuggerd/utility.h
+++ b/debuggerd/utility.h
@@ -67,12 +67,11 @@
LOGS
};
-/* Log information onto the tombstone. */
+// Log information onto the tombstone.
void _LOG(log_t* log, logtype ltype, const char *fmt, ...)
__attribute__ ((format(printf, 3, 4)));
-int wait_for_signal(pid_t tid, int* total_sleep_time_usec);
-void wait_for_stop(pid_t tid, int* total_sleep_time_usec);
+int wait_for_sigstop(pid_t, int*, bool*);
void dump_memory(log_t* log, pid_t tid, uintptr_t addr);