PR 9989 fix.

2009-03-24  David Smith  <dsmith@redhat.com>

	PR 9989.
	* runtime/task_finder.c (stap_utrace_detach): Ignores
	-EINPROGRESS.
	(stap_utrace_detach_ops): Ignores errors from
	stap_utrace_detach(), so that other tasks will get detached from
	this utrace engine.
	(__stp_utrace_attach): Better error handling from
	utrace_barrier().
	(__stp_utrace_task_finder_target_quiesce): Ditto.

diff --git a/runtime/task_finder.c b/runtime/task_finder.c
index 3f4908cb62c1b266b6b5e05d6e094aaeb69801b7..e494e7a88f0a0785094fceec3bce32a5df8a5b38 100644 (file)
--- a/runtime/task_finder.c
+++ b/runtime/task_finder.c
@@ -39,15 +39,23 @@ static atomic_t __stp_attach_count = ATOMIC_INIT (0);
 
 #define debug_task_finder_attach() (atomic_inc(&__stp_attach_count))
 #define debug_task_finder_detach() (atomic_dec(&__stp_attach_count))
+#ifdef DEBUG_TASK_FINDER_PRINTK
+#define debug_task_finder_report() (printk(KERN_ERR \
+                                          "%s:%d attach count: %d, inuse count: %d\n", \
+                                          __FUNCTION__, __LINE__,      \
+                                          atomic_read(&__stp_attach_count), \
+                                          atomic_read(&__stp_inuse_count)))
+#else
 #define debug_task_finder_report() (_stp_dbug(__FUNCTION__, __LINE__, \
                                              "attach count: %d, inuse count: %d\n", \
                                              atomic_read(&__stp_attach_count), \
                                              atomic_read(&__stp_inuse_count)))
+#endif /* !DEBUG_TASK_FINDER_PRINTK */
 #else
 #define debug_task_finder_attach()     /* empty */
 #define debug_task_finder_detach()     /* empty */
 #define debug_task_finder_report()     /* empty */
-#endif
+#endif /* !DEBUG_TASK_FINDER */
 
 typedef int (*stap_task_finder_callback)(struct stap_task_finder_target *tgt,
                                         struct task_struct *tsk,
@@ -280,11 +288,15 @@ stap_utrace_detach(struct task_struct *tsk,
                        break;
                case -ESRCH:        /* REAP callback already begun */
                case -EALREADY:     /* DEATH callback already begun */
-                       rc = 0;     /* ignore these errors*/
+                       rc = 0;     /* ignore these errors */
+                       break;
+               case -EINPROGRESS:
+                       debug_task_finder_detach();
+                       rc = 0;
                        break;
                default:
                        rc = -rc;
-                       _stp_error("utrace_detach returned error %d on pid %d",
+                       _stp_error("utrace_control returned error %d on pid %d",
                                   rc, tsk->pid);
                        break;
                }
@@ -298,7 +310,6 @@ stap_utrace_detach_ops(struct utrace_engine_ops *ops)
 {
        struct task_struct *grp, *tsk;
        struct utrace_attached_engine *engine;
-       int rc = 0;
        pid_t pid = 0;
 
        // Notice we're not calling get_task_mm() in this loop. In
@@ -324,11 +335,12 @@ stap_utrace_detach_ops(struct utrace_engine_ops *ops)
                        continue;
 #endif
 
-               rc = stap_utrace_detach(tsk, ops);
-               if (rc != 0)
-                       goto udo_err;
+               /* Notice we're purposefully ignoring errors from
+                * stap_utrace_detach().  Even if we got an error on
+                * this task, we need to keep detaching from other
+                * tasks. */
+               (void) stap_utrace_detach(tsk, ops);
        } while_each_thread(grp, tsk);
-udo_err:
        rcu_read_unlock();
        debug_task_finder_report();
 }
@@ -475,7 +487,7 @@ __stp_utrace_attach(struct task_struct *tsk,
                         * ref.
                         */
                        rc = utrace_barrier(tsk, engine);
-                       if (rc != 0)
+                       if (rc != -ESRCH && rc != -EALREADY)
                                _stp_error("utrace_barrier returned error %d on pid %d",
                                           rc, (int)tsk->pid);
                }
@@ -494,7 +506,7 @@ __stp_utrace_attach(struct task_struct *tsk,
                        }
 
                }
-               else
+               else if (rc != -ESRCH && rc != -EALREADY)
                        _stp_error("utrace_set_events2 returned error %d on pid %d",
                                   rc, (int)tsk->pid);
                utrace_engine_put(engine);
@@ -869,11 +881,12 @@ __stp_utrace_task_finder_target_quiesce(enum utrace_resume_action action,
                 * a stale task pointer, if we have an engine ref.
                 */
                rc = utrace_barrier(tsk, engine);
-               if (rc != 0)
+               if (rc == 0)
+                       rc = utrace_set_events(tsk, engine,
+                                              __STP_ATTACHED_TASK_BASE_EVENTS(tgt));
+               else if (rc != -ESRCH && rc != -EALREADY)
                        _stp_error("utrace_barrier returned error %d on pid %d",
                                   rc, (int)tsk->pid);
-               rc = utrace_set_events(tsk, engine,
-                                      __STP_ATTACHED_TASK_BASE_EVENTS(tgt));
        }
        if (rc != 0)
                _stp_error("utrace_set_events returned error %d on pid %d",