patch-0001-libxl-Add-a-utility-function-for-domain-resume.patch

From 6fcc32dc0747a081eb4b182dae1a483c6d1258f4 Mon Sep 17 00:00:00 2001
Message-Id: <6fcc32dc0747a081eb4b182dae1a483c6d1258f4.1664236600.git.demi@invisiblethingslab.com>
In-Reply-To: <cover.1664236600.git.demi@invisiblethingslab.com>
References: <cover.1664236600.git.demi@invisiblethingslab.com>
From: Demi Marie Obenour <demi@invisiblethingslab.com>
To: xen-devel@lists.xenproject.org
Cc: Wei Liu <wl@xen.org>
Cc: Anthony PERARD <anthony.perard@citrix.com>
Cc: Juergen Gross <jgross@suse.com>
Date: Mon, 26 Sep 2022 10:48:26 -0400
Subject: [PATCH 1/5] libxl: Add a utility function for domain resume

It is necessary to all xs_resume_domain after any successful call to
xc_domain_resume, so that XenStore is notified of the resumption.
However, it is also very easy to forget to call this.  This took me
several days to debug.

Fix this by adding a utility function to resume a domain and then notify
XenStore of the resumption.  This function does not resume any device
model, so it is still internal to libxl, but it makes future changes to
libxl much less error-prone.  It also makes libxl itself smaller.

Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>

-----------
diff --git a/tools/libs/light/libxl_dom_suspend.c b/tools/libs/light/libxl_dom_suspend.c
index 4fa22bb7..fa50e880 100644
--- a/tools/libs/light/libxl_dom_suspend.c
+++ b/tools/libs/light/libxl_dom_suspend.c
@@ -451,6 +451,22 @@ int libxl__domain_resume_device_model_deprecated(libxl__gc *gc, uint32_t domid)
     return 0;
 }
 
+/* Just resumes the domain.  The device model must have been resumed already. */
+static int domain_resume_raw(libxl__gc *gc, uint32_t domid, int suspend_cancel)
+{
+    if (xc_domain_resume(CTX->xch, domid, suspend_cancel)) {
+        LOGED(ERROR, domid, "xc_domain_resume failed");
+        return ERROR_FAIL;
+    }
+
+    if (!xs_resume_domain(CTX->xsh, domid)) {
+        LOGED(ERROR, domid, "xs_resume_domain failed");
+        return ERROR_FAIL;
+    }
+
+    return 0;
+}
+
 int libxl__domain_resume_deprecated(libxl__gc *gc, uint32_t domid, int suspend_cancel)
 {
     int rc = 0;
@@ -469,16 +485,7 @@ int libxl__domain_resume_deprecated(libxl__gc *gc, uint32_t domid, int suspend_c
         }
     }
 
-    if (xc_domain_resume(CTX->xch, domid, suspend_cancel)) {
-        LOGED(ERROR, domid, "xc_domain_resume failed");
-        rc = ERROR_FAIL;
-        goto out;
-    }
-
-    if (!xs_resume_domain(CTX->xsh, domid)) {
-        LOGED(ERROR, domid, "xs_resume_domain failed");
-        rc = ERROR_FAIL;
-    }
+    rc = domain_resume_raw(gc, domid, suspend_cancel);
 out:
     return rc;
 }
@@ -660,19 +667,9 @@ static void domain_resume_done(libxl__egc *egc,
     /* Convenience aliases */
     libxl_domid domid = dmrs->domid;
 
-    if (rc) goto out;
-
-    if (xc_domain_resume(CTX->xch, domid, dmrs->suspend_cancel)) {
-        LOGED(ERROR, domid, "xc_domain_resume failed");
-        rc = ERROR_FAIL;
-        goto out;
-    }
+    if (!rc)
+        rc = domain_resume_raw(gc, domid, dmrs->suspend_cancel);
 
-    if (!xs_resume_domain(CTX->xsh, domid)) {
-        LOGED(ERROR, domid, "xs_resume_domain failed");
-        rc = ERROR_FAIL;
-    }
-out:
     dmrs->callback(egc, dmrs, rc);
 }
 
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