2007-07-05 Jan Kratochvil <jan.kratochvil@redhat.com>
* strace.c (detach): New prototype. Extended the function comment.
[LINUX] (detach): Call droptcb() instead of the wrongly parametrized
detach() call.
(handle_group_exit): Call droptcb() instead of the wrongly parametrized
detach() call. Always call detach() only once from the group leader.
Comment the leader killing known bug tested by `test/leaderkill.c'.
Code advisory: Roland McGrath
Fixes RH#240961.
diff --git a/strace.c b/strace.c
index 4e86040..ce982dc 100644
--- a/strace.c
+++ b/strace.c
@@ -98,6 +98,7 @@
char *progname;
extern char **environ;
+static int detach P((struct tcb *tcp, int sig));
static int trace P((void));
static void cleanup P((void));
static void interrupt P((int sig));
@@ -1332,7 +1333,10 @@
#endif /* !USE_PROCFS */
-/* detach traced process; continue with sig */
+/* detach traced process; continue with sig
+ Never call DETACH twice on the same process as both unattached and
+ attached-unstopped processes give the same ESRCH. For unattached process we
+ would SIGSTOP it and wait for its SIGSTOP notification forever. */
static int
detach(tcp, sig)
@@ -1521,8 +1525,10 @@
droptcb(tcp);
#ifdef LINUX
- if (zombie != NULL)
- error = detach(zombie) || error;
+ if (zombie != NULL) {
+ /* TCP no longer exists therefore you must not detach () it. */
+ droptcb(zombie);
+ }
#endif
return error;
@@ -2096,14 +2102,16 @@
fprintf(stderr,
"PANIC: handle_group_exit: %d leader %d\n",
tcp->pid, leader ? leader->pid : -1);
- detach(tcp); /* Already died. */
+ /* TCP no longer exists therefore you must not detach () it. */
+ droptcb(tcp); /* Already died. */
}
else {
/* Mark that we are taking the process down. */
tcp->flags |= TCB_EXITING | TCB_GROUP_EXITING;
if (tcp->flags & TCB_ATTACHED) {
if (leader != NULL && leader != tcp) {
- if (leader->flags & TCB_ATTACHED) {
+ if ((leader->flags & TCB_ATTACHED) &&
+ !(leader->flags & TCB_EXITING)) {
/* We need to detach the leader so
that the process death will be
reported to its real parent.
@@ -2115,7 +2123,10 @@
stopped. Then the value we pass
in PTRACE_DETACH just sets the
death signal reported to the
- real parent. */
+ real parent.
+ FIXME: This killing gets caught by
+ WAITPID of the leader's parent.
+ Testcase: test/leaderkill.c */
ptrace(PTRACE_KILL, leader->pid, 0, 0);
if (debug)
fprintf(stderr,