From: cl349@firebug.cl.cam.ac.uk <cl349@firebug.cl.cam.ac.uk>
Date: Wed, 14 Sep 2005 08:41:49 +0000 (+0000)
Subject: Fix xenstored watch crash.
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~16806^2~23
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/%22/%22http:/www.example.com/cgi/%22?a=commitdiff_plain;h=2c0ba8d0753536c7cd9651b0326bcfabd2d20e18;p=xen.git

Fix xenstored watch crash.
When a connection blocked waiting on a transaction, don't queue watch events.
Sure, they'd be ignored and re-transmitted, but it hits an assert that we don't
send data out blocked connections, and it's wasteful.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (authored)
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
---

diff --git a/tools/xenstore/testsuite/16block-watch-crash.test b/tools/xenstore/testsuite/16block-watch-crash.test
new file mode 100644
index 0000000000..564f6d31ed
--- /dev/null
+++ b/tools/xenstore/testsuite/16block-watch-crash.test
@@ -0,0 +1,13 @@
+# Test case where blocked connection gets sent watch.
+
+mkdir /test
+watch /test token
+1 start /test
+# This will block on above
+noackwrite /test/entry create contents
+1 write /test/entry2 create contents
+1 commit
+readack
+expect /test/entry2:token
+waitwatch
+ackwatch token
diff --git a/tools/xenstore/xenstored_watch.c b/tools/xenstore/xenstored_watch.c
index e40318ee2f..a543f8a495 100644
--- a/tools/xenstore/xenstored_watch.c
+++ b/tools/xenstore/xenstored_watch.c
@@ -144,7 +144,7 @@ void fire_watches(struct connection *conn, const char *node, bool recurse)
 			else
 				continue;
 			/* If connection not doing anything, queue this. */
-			if (!i->out)
+			if (i->state == OK)
 				queue_next_event(i);
 		}
 	}
diff --git a/tools/xenstore/xs_test.c b/tools/xenstore/xs_test.c
index 58445b9f25..6f4d0d5bc4 100644
--- a/tools/xenstore/xs_test.c
+++ b/tools/xenstore/xs_test.c
@@ -398,12 +398,16 @@ static void do_noackwrite(unsigned int handle,
 static void do_readack(unsigned int handle)
 {
 	enum xsd_sockmsg_type type;
-	char *ret;
-
-	ret = read_reply(handles[handle]->fd, &type, NULL);
-	if (!ret)
-		failed(handle);
-	free(ret);
+	char *ret = NULL;
+
+	/* Watches can have fired before reply comes: daemon detects
+	 * and re-transmits, so we can ignore this. */
+	do {
+		free(ret);
+		ret = read_reply(handles[handle]->fd, &type, NULL);
+		if (!ret)
+			failed(handle);
+	} while (type == XS_WATCH_EVENT);
 }
 
 static void do_setid(unsigned int handle, char *id)