From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Fri, 4 Jul 2014 16:06:20 +0000 (+0100)
Subject: tools/xenctx: Correct use of xc_domain_{, un}pause()
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~4690
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=6de560fadabb8a19887aa4320857088dba9a2b95;p=xen.git

tools/xenctx: Correct use of xc_domain_{, un}pause()

The previous code never worked correctly.  There was a TOCTOU race between
checking dominfo and pausing the domain.

Since c/s 3eb1c708, Xen properly reference counts pause hypercalls, so
unconditionally pause and unpause the domain.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Ian Campbell <Ian.Campbell@citrix.com>
CC: Ian Jackson <Ian.Jackson@eu.citrix.com>
CC: George Dunlap <george.dunlap@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
---

diff --git a/tools/xentrace/xenctx.c b/tools/xentrace/xenctx.c
index 82bd789559..4ed120a6a8 100644
--- a/tools/xentrace/xenctx.c
+++ b/tools/xentrace/xenctx.c
@@ -91,7 +91,6 @@ static struct xenctx {
     int do_stack;
 #endif
     int kernel_start_set;
-    int self_paused;
     xc_dominfo_t dominfo;
 } xenctx;
 
@@ -1273,13 +1272,10 @@ int main(int argc, char **argv)
         exit(-1);
     }
 
-    if (!xenctx.dominfo.paused) {
-        ret = xc_domain_pause(xenctx.xc_handle, xenctx.domid);
-        if (ret < 0) {
-            perror("xc_domain_pause");
-            exit(-1);
-        }
-        xenctx.self_paused = 1;
+    ret = xc_domain_pause(xenctx.xc_handle, xenctx.domid);
+    if (ret < 0) {
+        perror("xc_domain_pause");
+        exit(-1);
     }
 
 #ifndef NO_TRANSLATION
@@ -1303,12 +1299,10 @@ int main(int argc, char **argv)
     if ( do_default )
         dump_ctx(vcpu);
 
-    if (xenctx.self_paused) {
-        ret = xc_domain_unpause(xenctx.xc_handle, xenctx.domid);
-        if (ret < 0) {
-            perror("xc_domain_unpause");
-            exit(-1);
-        }
+    ret = xc_domain_unpause(xenctx.xc_handle, xenctx.domid);
+    if (ret < 0) {
+        perror("xc_domain_unpause");
+        exit(-1);
     }
 
     ret = xc_interface_close(xenctx.xc_handle);