libxl: events: Make timeout and async exec setup take an ao, not a gc

Change the timeout setup functions to take a libxl__ao, not a
libxl__gc.  This is going to be needed for ao abort, because timeouts
are going to be a main hook for ao abort requests - so the timeouts
need to be associated with an ao.

This means that timeouts can only occur as part of a long-running
libxl function (but this is of course correct, as libxl shouldn't have
any global timeouts, and indeed all the call sites have an ao).

Also remove the gc parameter from libxl__async_exec_start.  It can
just use the gc from the ao supplied in the aes.

All the callers follow the obvious patterns and therefore supply the
ao's gc to libxl__async_exec_start and the timeout setup functions.
There is therefore no functional change in this patch.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
CC: Yang Hongyang <yanghy@cn.fujitsu.com>
CC: Wen Congyang <wency@cn.fujitsu.com>
CC: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Wen Congyang <wency@cn.fujitsu.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

---
v2: This patch split off from "Permit timeouts to signal cancellation".
    Rebased; consequently, deal with libxl__async_exec_start.
    CC'd authors of the libxl__async_exec_* functions.

tools/libxl/libxl_aoutils.c

@@ -46,7 +46,7 @@ int libxl__xswait_start(libxl__gc *gc, libxl__xswait_state *xswa)
 {
     int rc;
 
-    rc = libxl__ev_time_register_rel(gc, &xswa->time_ev,
+    rc = libxl__ev_time_register_rel(xswa->ao, &xswa->time_ev,
                                      xswait_timeout_callback, xswa->timeout_ms);
     if (rc) goto err;
 
@@ -547,16 +547,18 @@ void libxl__async_exec_init(libxl__async_exec_state *aes)
     libxl__ev_child_init(&aes->child);
 }
 
-int libxl__async_exec_start(libxl__gc *gc, libxl__async_exec_state *aes)
+int libxl__async_exec_start(libxl__async_exec_state *aes)
 {
     pid_t pid;
 
     /* Convenience aliases */
+    libxl__ao *ao = aes->ao;
+    AO_GC;
     libxl__ev_child *const child = &aes->child;
     char ** const args = aes->args;
 
     /* Set execution timeout */
-    if (libxl__ev_time_register_rel(gc, &aes->time,
+    if (libxl__ev_time_register_rel(ao, &aes->time,
                                     async_exec_timeout,
                                     aes->timeout_ms)) {
         LOG(ERROR, "unable to register timeout for executing: %s", aes->what);

tools/libxl/libxl_device.c

@@ -808,7 +808,7 @@ void libxl__initiate_device_remove(libxl__egc *egc,
              * TODO: 4.2 Bodge due to QEMU, see comment on top of
              * libxl__initiate_device_remove in libxl_internal.h
              */
-            rc = libxl__ev_time_register_rel(gc, &aodev->timeout,
+            rc = libxl__ev_time_register_rel(ao, &aodev->timeout,
                                              device_qemu_timeout,
                                              LIBXL_QEMU_BODGE_TIMEOUT * 1000);
             if (rc) {
@@ -1034,7 +1034,7 @@ static void device_hotplug(libxl__egc *egc, libxl__ao_device *aodev)
     aes->stdfds[1] = 2;
     aes->stdfds[2] = -1;
 
-    rc = libxl__async_exec_start(gc, aes);
+    rc = libxl__async_exec_start(aes);
     if (rc)
         goto out;
 

tools/libxl/libxl_dom.c

@@ -1200,7 +1200,7 @@ static void domain_suspend_switch_qemu_xen_traditional_logdirty
                                 switch_logdirty_xswatch, lds->ret_path);
     if (rc) goto out;
 
-    rc = libxl__ev_time_register_rel(gc, &lds->timeout,
+    rc = libxl__ev_time_register_rel(ao, &lds->timeout,
                                 switch_logdirty_timeout, 10*1000);
     if (rc) goto out;
 
@@ -1480,7 +1480,7 @@ static void domain_suspend_callback_common(libxl__egc *egc,
         rc = libxl__ev_evtchn_wait(gc, &dss->guest_evtchn);
         if (rc) goto err;
 
-        rc = libxl__ev_time_register_rel(gc, &dss->guest_timeout,
+        rc = libxl__ev_time_register_rel(ao, &dss->guest_timeout,
                                          suspend_common_wait_guest_timeout,
                                          60*1000);
         if (rc) goto err;
@@ -1611,7 +1611,7 @@ static void domain_suspend_common_wait_guest(libxl__egc *egc,
                                     "@releaseDomain");
     if (rc) goto err;
 
-    rc = libxl__ev_time_register_rel(gc, &dss->guest_timeout,
+    rc = libxl__ev_time_register_rel(ao, &dss->guest_timeout,
                                      suspend_common_wait_guest_timeout,
                                      60*1000);
     if (rc) goto err;
@@ -1990,7 +1990,7 @@ static void remus_devices_commit_cb(libxl__egc *egc,
      */
 
     /* Set checkpoint interval timeout */
-    rc = libxl__ev_time_register_rel(gc, &dss->checkpoint_timeout,
+    rc = libxl__ev_time_register_rel(ao, &dss->checkpoint_timeout,
                                      remus_next_checkpoint,
                                      dss->interval);
 

tools/libxl/libxl_event.c

@@ -332,10 +332,11 @@ static void time_done_debug(libxl__gc *gc, const char *func,
 #endif
 }
 
-int libxl__ev_time_register_abs(libxl__gc *gc, libxl__ev_time *ev,
+int libxl__ev_time_register_abs(libxl__ao *ao, libxl__ev_time *ev,
                                 libxl__ev_time_callback *func,
                                 struct timeval absolute)
 {
+    AO_GC;
     int rc;
 
     CTX_LOCK;
@@ -356,10 +357,11 @@ int libxl__ev_time_register_abs(libxl__gc *gc, libxl__ev_time *ev,
 }
 
 
-int libxl__ev_time_register_rel(libxl__gc *gc, libxl__ev_time *ev,
+int libxl__ev_time_register_rel(libxl__ao *ao, libxl__ev_time *ev,
                                 libxl__ev_time_callback *func,
                                 int milliseconds /* as for poll(2) */)
 {
+    AO_GC;
     struct timeval absolute;
     int rc;
 

tools/libxl/libxl_internal.h

@@ -791,10 +791,10 @@ static inline void libxl__ev_fd_init(libxl__ev_fd *efd)
 static inline int libxl__ev_fd_isregistered(const libxl__ev_fd *efd)
                     { return efd->fd >= 0; }
 
-_hidden int libxl__ev_time_register_rel(libxl__gc*, libxl__ev_time *ev_out,
+_hidden int libxl__ev_time_register_rel(libxl__ao*, libxl__ev_time *ev_out,
                                         libxl__ev_time_callback*,
                                         int milliseconds /* as for poll(2) */);
-_hidden int libxl__ev_time_register_abs(libxl__gc*, libxl__ev_time *ev_out,
+_hidden int libxl__ev_time_register_abs(libxl__ao*, libxl__ev_time *ev_out,
                                         libxl__ev_time_callback*,
                                         struct timeval);
 _hidden int libxl__ev_time_modify_rel(libxl__gc*, libxl__ev_time *ev,
@@ -2166,7 +2166,7 @@ struct libxl__async_exec_state {
 };
 
 void libxl__async_exec_init(libxl__async_exec_state *aes);
-int libxl__async_exec_start(libxl__gc *gc, libxl__async_exec_state *aes);
+int libxl__async_exec_start(libxl__async_exec_state *aes);
 bool libxl__async_exec_inuse(const libxl__async_exec_state *aes);
 
 /*----- device addition/removal -----*/

tools/libxl/libxl_remus_disk_drbd.c

@@ -120,7 +120,7 @@ static void match_async_exec(libxl__egc *egc, libxl__remus_device *dev)
     aes->stdfds[1] = -1;
     aes->stdfds[2] = -1;
 
-    rc = libxl__async_exec_start(gc, aes);
+    rc = libxl__async_exec_start(aes);
     if (rc)
         goto out;
 

tools/libxl/libxl_test_timedereg.c

@@ -30,12 +30,13 @@ static int seq;
 static void occurs(libxl__egc *egc, libxl__ev_time *ev,
                    const struct timeval *requested_abs);
 
-static void regs(libxl__gc *gc, int j)
+static void regs(libxl__ao *ao, int j)
 {
+    AO_GC;
     int rc, i;
     LOG(DEBUG,"regs(%d)", j);
     for (i=0; i<NTIMES; i++) {
-        rc = libxl__ev_time_register_rel(gc, &et[j][i], occurs, ms[j][i]);
+        rc = libxl__ev_time_register_rel(ao, &et[j][i], occurs, ms[j][i]);
         assert(!rc);
     }    
 }
@@ -52,7 +53,7 @@ int libxl_test_timedereg(libxl_ctx *ctx, libxl_asyncop_how *ao_how)
         libxl__ev_time_init(&et[1][i]);
     }
 
-    regs(gc, 0);
+    regs(ao, 0);
 
     return AO_INPROGRESS;
 }
@@ -71,7 +72,7 @@ static void occurs(libxl__egc *egc, libxl__ev_time *ev,
         assert(ev == &et[0][1]);
         libxl__ev_time_deregister(gc, &et[0][0]);
         libxl__ev_time_deregister(gc, &et[0][2]);
-        regs(gc, 1);
+        regs(tao, 1);
         libxl__ev_time_deregister(gc, &et[0][1]);
         break;