From: David Goulet <dgoulet@efficios.com>
Date: Tue, 30 Oct 2012 19:11:18 +0000 (-0400)
Subject: Fix: Bad return error code handling
X-Git-Tag: v2.1.0-rc6~6
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=5b98a7741b64765b34396a151b976f8f58ee3a5e;p=lttng-tools.git

Fix: Bad return error code handling

Two things here. First, if the tracer dies before we have time to create
the session on it, the returned value (-1) was not handled creating a
segfault on the following loop.

Second, we no longer assert on the application PID hash table delete
return value since we use add_replace on app. registration creating a
possible key reuse for a different node.

Signed-off-by: David Goulet <dgoulet@efficios.com>
---

diff --git a/src/bin/lttng-sessiond/ust-app.c b/src/bin/lttng-sessiond/ust-app.c
index 96f8eb0b3..e0562ed4e 100644
--- a/src/bin/lttng-sessiond/ust-app.c
+++ b/src/bin/lttng-sessiond/ust-app.c
@@ -1506,8 +1506,16 @@ void ust_app_unregister(int sock)
 	/* Assign second node for deletion */
 	iter.iter.node = &lta->pid_n.node;
 
+	/*
+	 * Ignore return value since the node might have been removed before by an
+	 * add replace during app registration because the PID can be reassigned by
+	 * the OS.
+	 */
 	ret = lttng_ht_del(ust_app_ht, &iter);
-	assert(!ret);
+	if (ret) {
+		DBG3("Unregister app by PID %d failed. This can happen on pid reuse",
+				lta->pid);
+	}
 
 	/* Free memory */
 	call_rcu(&lta->pid_n.head, delete_ust_app_rcu);
@@ -2555,7 +2563,8 @@ void ust_app_global_update(struct ltt_ust_session *usess, int sock)
 	}
 
 	ua_sess = create_ust_app_session(usess, app);
-	if (ua_sess == NULL) {
+	if (ua_sess == NULL || ua_sess == (void *) -1UL) {
+		/* Tracer is gone for this session and has been freed */
 		goto error;
 	}