From 939629eb5b1f143b12eee9396d6a8c8b1e0f3226 Mon Sep 17 00:00:00 2001
From: Keir Fraser <keir.fraser@citrix.com>
Date: Fri, 22 Jan 2010 11:00:45 +0000
Subject: blktap: fix blktapctrl abort

On rebooting a hvm, the blktapctrl daemon has died.

gdb shows the following call trace:
(gdb) where
#0  0x00000039d1830155 in raise () from /lib64/libc.so.6
#1  0x00000039d1831bf0 in abort () from /lib64/libc.so.6
#2  0x00000039d186a38b in __libc_message () from /lib64/libc.so.6
#3  0x00000039d1871634 in _int_free () from /lib64/libc.so.6
#4  0x00000039d1874c5c in free () from /lib64/libc.so.6
#5  0x0000003320a01bdd in ueblktap_probe (h=3D0x6073b0,=20
    w=<value optimized out>, bepath_im=<value optimized out>) at
    xenbus.c:270
#6  0x0000003320a020e0 in xs_fire_next_watch (h=3D0x6073b0) at
xs_api.c:355
#7  0x0000000000401785 in main (argc=3D<value optimized out>,
    argv=<value optimized out>) at blktapctrl.c:907

There is a case that "/local/domain/0/backend/tap/<dom_id>" exists but
"/local/domain/<dom_id>/vm" is not in the xenstore.

Signed-off-by: Kouya Shimura <kouya@jp.fujitsu.com>
---
 tools/blktap/lib/xenbus.c | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'tools/blktap')

diff --git a/tools/blktap/lib/xenbus.c b/tools/blktap/lib/xenbus.c
index c238d5fe9a..53db3c8b29 100644
--- a/tools/blktap/lib/xenbus.c
+++ b/tools/blktap/lib/xenbus.c
@@ -232,8 +232,11 @@ static int check_sharing(struct xs_handle *h, struct backend_info *be)
 			ret = -1;
 			break;
 		}
+		cur_dom_uuid = NULL;
 		xs_gather(h, path, "vm", NULL, &cur_dom_uuid, NULL);
 		free(path);
+		if (!cur_dom_uuid)
+			continue;
 
 		if (!strcmp(cur_dom_uuid, dom_uuid)) {
 			free(cur_dom_uuid);
@@ -256,8 +259,11 @@ static int check_sharing(struct xs_handle *h, struct backend_info *be)
 				ret = -1;
 				break;
 			}
+			params = NULL;
 			xs_gather(h, path, "params", NULL, &params, NULL);
 			free(path);
+			if (!params)
+				continue;
 
 			image_path[1] = get_image_path(params);
 			if (!strcmp(image_path[0], image_path[1])) {
-- 
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