[Xen-changelog] [xen master] libxl: trigger attach events for devices attached before xl devd startup

[patchbot@xxxxxxx]

commit 7d9fa19ec43b05e82443f49eee24d78dd1a3565c
Author:     Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
AuthorDate: Sat Jul 16 01:47:56 2016 +0200
Commit:     Wei Liu <wei.liu2@xxxxxxxxxx>
CommitDate: Tue Jul 19 14:12:06 2016 +0100

    libxl: trigger attach events for devices attached before xl devd startup
    
    When this daemon is started after creating backend device, that device
    will not be configured.
    
    Racy situation:
    1. driver domain is started
    2. frontend domain is started (just after kicking driver domain off)
    3. device in frontend domain is connected to the backend (as specified
       in frontend domain configuration)
    4. xl devd is started in driver domain
    
    End result is that backend device in driver domain is not configured
    (like network interface is not enabled), so the device doesn't work.
    
    Fix this by artifically triggering events for devices already present in
    xenstore before xl devd is started. Do this only after xenstore watch is
    already registered, and only for devices not already initialized (in
    XenbusStateInitWait state).
    
    Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
    Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
    Signed-off-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
    Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/libxl/libxl.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 2cf7451..b5f9084 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -4658,6 +4658,12 @@ int libxl_device_events_handler(libxl_ctx *ctx,
     uint32_t domid;
     libxl__ddomain ddomain;
     char *be_path;
+    char **kinds = NULL, **domains = NULL, **devs = NULL;
+    const char *sstate;
+    char *state_path;
+    int state;
+    unsigned int nkinds, ndomains, ndevs;
+    int i, j, k;
 
     ddomain.ao = ao;
     LIBXL_SLIST_INIT(&ddomain.guests);
@@ -4677,6 +4683,33 @@ int libxl_device_events_handler(libxl_ctx *ctx,
                                     be_path);
     if (rc) goto out;
 
+    kinds = libxl__xs_directory(gc, XBT_NULL, be_path, &nkinds);
+    if (kinds) {
+        for (i = 0; i < nkinds; i++) {
+            domains = libxl__xs_directory(gc, XBT_NULL,
+                    GCSPRINTF("%s/%s", be_path, kinds[i]), &ndomains);
+            if (!domains)
+                continue;
+            for (j = 0; j < ndomains; j++) {
+                devs = libxl__xs_directory(gc, XBT_NULL,
+                        GCSPRINTF("%s/%s/%s", be_path, kinds[i], domains[j]), 
&ndevs);
+                if (!devs)
+                    continue;
+                for (k = 0; k < ndevs; k++) {
+                    state_path = GCSPRINTF("%s/%s/%s/%s/state",
+                            be_path, kinds[i], domains[j], devs[k]);
+                    rc = libxl__xs_read_checked(gc, XBT_NULL, state_path, 
&sstate);
+                    if (rc || !sstate)
+                        continue;
+                    state = atoi(sstate);
+                    if (state == XenbusStateInitWait)
+                        backend_watch_callback(egc, &ddomain.watch,
+                                               be_path, state_path);
+                }
+            }
+        }
+    }
+
     return AO_INPROGRESS;
 
 out:
--
generated by git-patchbot for /home/xen/git/xen.git#master

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