libxl: event: Make LIBXL__EVENT_DISASTER take a gc, not an egc

We are going to want to change libxl__poller_wakeup to take a gc.

In theory there is a risk here that it would be called inappropriately
in a future patch but this seems unlikely.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Tested-by: George Dunlap <george.dunlap@citrix.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
---
v2: New patch

tools/libxl/libxl_aoutils.c

@@ -282,7 +282,7 @@ static void datacopier_readable(libxl__egc *egc, libxl__ev_fd *ev,
                 hupchk.revents = 0;
                 r = poll(&hupchk, 1, 0);
                 if (r < 0)
-                    LIBXL__EVENT_DISASTER(egc,
+                    LIBXL__EVENT_DISASTER(gc,
      "unexpected failure polling fd for datacopier eof hup check",
                                   errno, 0);
                 if (datacopier_pollhup_handled(egc, dc, fd, hupchk.revents, 0))

tools/libxl/libxl_disk.c

@@ -33,7 +33,7 @@ static void disk_eject_xswatch_callback(libxl__egc *egc, libxl__ev_xswatch *w,
         return;
 
     if (libxl__xs_printf(gc, XBT_NULL, wpath, "")) {
-        LIBXL__EVENT_DISASTER(egc, "xs_write failed acknowledging eject",
+        LIBXL__EVENT_DISASTER(gc, "xs_write failed acknowledging eject",
                               errno, LIBXL_EVENT_TYPE_DISK_EJECT);
         return;
     }
@@ -43,7 +43,7 @@ static void disk_eject_xswatch_callback(libxl__egc *egc, libxl__ev_xswatch *w,
 
     rc = libxl__xs_read_checked(gc, XBT_NULL, evg->be_ptr_path, &backend);
     if (rc) {
-        LIBXL__EVENT_DISASTER(egc, "xs_read failed reading be_ptr_path",
+        LIBXL__EVENT_DISASTER(gc, "xs_read failed reading be_ptr_path",
                               errno, LIBXL_EVENT_TYPE_DISK_EJECT);
         return;
     }

tools/libxl/libxl_domain.c

@@ -892,7 +892,7 @@ static void domain_death_xswatch_callback(libxl__egc *egc, libxl__ev_xswatch *w,
 
         rc = xc_domain_getinfolist(CTX->xch, evg->domid, nentries, domaininfos);
         if (rc == -1) {
-            LIBXL__EVENT_DISASTER(egc, "xc_domain_getinfolist failed while"
+            LIBXL__EVENT_DISASTER(gc, "xc_domain_getinfolist failed while"
                                   " processing @releaseDomain watch event",
                                   errno, 0);
             goto out;

tools/libxl/libxl_event.c

@@ -261,7 +261,7 @@ short libxl__fd_poll_recheck(libxl__egc *egc, int fd, short events) {
             break;
         assert(r<0);
         if (errno != EINTR) {
-            LIBXL__EVENT_DISASTER(egc, "failed poll to check for fd", errno, 0);
+            LIBXL__EVENT_DISASTER(gc, "failed poll to check for fd", errno, 0);
             return 0;
         }
     }
@@ -509,14 +509,14 @@ static void watchfd_callback(libxl__egc *egc, libxl__ev_fd *ev,
     EGC_GC;
 
     if (revents & (POLLERR|POLLHUP))
-        LIBXL__EVENT_DISASTER(egc, "unexpected poll event on watch fd", 0, 0);
+        LIBXL__EVENT_DISASTER(gc, "unexpected poll event on watch fd", 0, 0);
 
     for (;;) {
         char **event = xs_check_watch(CTX->xsh);
         if (!event) {
             if (errno == EAGAIN) break;
             if (errno == EINTR) continue;
-            LIBXL__EVENT_DISASTER(egc, "cannot check/read watches", errno, 0);
+            LIBXL__EVENT_DISASTER(gc, "cannot check/read watches", errno, 0);
             return;
         }
 
@@ -705,7 +705,7 @@ static int evtchn_revents_check(libxl__egc *egc, int revents)
 
     if (revents & ~POLLIN) {
         LOG(ERROR, "unexpected poll event on event channel fd: %x", revents);
-        LIBXL__EVENT_DISASTER(egc,
+        LIBXL__EVENT_DISASTER(gc,
                    "unexpected poll event on event channel fd", 0, 0);
         libxl__ev_fd_deregister(gc, &CTX->evtchn_efd);
         return ERROR_FAIL;
@@ -746,7 +746,7 @@ static void evtchn_fd_callback(libxl__egc *egc, libxl__ev_fd *ev,
         if (port < 0) {
             if (errno == EAGAIN)
                 break;
-            LIBXL__EVENT_DISASTER(egc,
+            LIBXL__EVENT_DISASTER(gc,
      "unexpected failure fetching occurring event port number from evtchn",
                                   errno, 0);
             return;
@@ -966,7 +966,7 @@ static void domaindeathcheck_callback(libxl__egc *egc, libxl__ev_xswatch *w,
     libxl__domaindeathcheck_stop(gc,dc);
 
     if (errno!=ENOENT) {
-        LIBXL__EVENT_DISASTER(egc,"failed to read xenstore"
+        LIBXL__EVENT_DISASTER(gc,"failed to read xenstore"
                               " for domain detach check", errno, 0);
         return;
     }
@@ -1279,7 +1279,7 @@ static void afterpoll_internal(libxl__egc *egc, libxl__poller *poller,
 
     if (afterpoll_check_fd(poller,fds,nfds, poller->wakeup_pipe[0],POLLIN)) {
         int e = libxl__self_pipe_eatall(poller->wakeup_pipe[0]);
-        if (e) LIBXL__EVENT_DISASTER(egc, "read wakeup", e, 0);
+        if (e) LIBXL__EVENT_DISASTER(gc, "read wakeup", e, 0);
     }
 
     for (;;) {
@@ -1365,12 +1365,10 @@ void libxl_osevent_occurred_timeout(libxl_ctx *ctx, void *for_libxl)
     CTX_UNLOCK_EGC_FREE;
 }
 
-void libxl__event_disaster(libxl__egc *egc, const char *msg, int errnoval,
+void libxl__event_disaster(libxl__gc *gc, const char *msg, int errnoval,
                            libxl_event_type type /* may be 0 */,
                            const char *file, int line, const char *func)
 {
-    EGC_GC;
-
     libxl__log(CTX, XTL_CRITICAL, errnoval, file, line, func, INVALID_DOMID,
                "DISASTER in event loop: %s%s%s%s",
                msg,
@@ -1672,8 +1670,9 @@ void libxl__poller_put(libxl_ctx *ctx, libxl__poller *p)
 
 void libxl__poller_wakeup(libxl__egc *egc, libxl__poller *p)
 {
+    EGC_GC;
     int e = libxl__self_pipe_wakeup(p->wakeup_pipe[1]);
-    if (e) LIBXL__EVENT_DISASTER(egc, "cannot poke watch pipe", e, 0);
+    if (e) LIBXL__EVENT_DISASTER(gc, "cannot poke watch pipe", e, 0);
 }
 
 /*

tools/libxl/libxl_fork.c

@@ -211,6 +211,7 @@ int libxl__carefd_fd(const libxl__carefd *cf)
 /* Like waitpid(,,WNOHANG) but handles all errors except ECHILD. */
 static pid_t checked_waitpid(libxl__egc *egc, pid_t want, int *status)
 {
+    EGC_GC;
     for (;;) {
         pid_t got = waitpid(want, status, WNOHANG);
         if (got != -1)
@@ -219,7 +220,7 @@ static pid_t checked_waitpid(libxl__egc *egc, pid_t want, int *status)
             return got;
         if (errno == EINTR)
             continue;
-        LIBXL__EVENT_DISASTER(egc, "waitpid() failed", errno, 0);
+        LIBXL__EVENT_DISASTER(gc, "waitpid() failed", errno, 0);
         return 0;
     }
 }
@@ -507,7 +508,7 @@ static void childproc_checkall(libxl__egc *egc)
     found:
         if (got == -1) {
             LIBXL__EVENT_DISASTER
-                (egc, "waitpid() gave ECHILD but we have a child",
+                (gc, "waitpid() gave ECHILD but we have a child",
                  ECHILD, 0);
             /* it must have finished but we don't know its status */
             status = 255<<8; /* no wait.h macro for this! */
@@ -545,14 +546,14 @@ static void sigchld_selfpipe_handler(libxl__egc *egc, libxl__ev_fd *ev,
 
     if (revents & ~POLLIN) {
         LOG(ERROR, "unexpected poll event 0x%x on SIGCHLD self pipe", revents);
-        LIBXL__EVENT_DISASTER(egc,
+        LIBXL__EVENT_DISASTER(gc,
                               "unexpected poll event on SIGCHLD self pipe",
                               0, 0);
     }
     assert(revents & POLLIN);
 
     int e = libxl__self_pipe_eatall(selfpipe);
-    if (e) LIBXL__EVENT_DISASTER(egc, "read sigchld pipe", e, 0);
+    if (e) LIBXL__EVENT_DISASTER(gc, "read sigchld pipe", e, 0);
 
     if (CTX->childproc_hooks->chldowner
         == libxl_sigchld_owner_libxl_always_selective_reap) {
@@ -581,7 +582,7 @@ static void sigchld_selfpipe_handler(libxl__egc *egc, libxl__ev_fd *ev,
                              " libxl_childproc_hooks->reaped_callback"
                              " (for pid=%lu, status=%d; error code %d)",
                              (unsigned long)pid, status, rc);
-                    LIBXL__EVENT_DISASTER(egc, disasterbuf, 0, 0);
+                    LIBXL__EVENT_DISASTER(gc, disasterbuf, 0, 0);
                     return;
                 }
             } else {

tools/libxl/libxl_internal.h

@@ -1281,8 +1281,8 @@ _hidden libxl_event *libxl__event_new(libxl__egc*, libxl_event_type,
 /*
  * In general, call this via the macro LIBXL__EVENT_DISASTER.
  *
- * Event-generating functions may call this if they might have wanted
- * to generate an event (either an internal one ie a
+ * Event-generating functions, or ao machinery, may call this if they
+ * might have wanted to generate an event (either an internal one ie a
  * libxl__ev_FOO_callback or an application event), but are prevented
  * from doing so due to eg lack of memory.
  *
@@ -1290,12 +1290,12 @@ _hidden libxl_event *libxl__event_new(libxl__egc*, libxl_event_type,
  * then crash, although it may fail (and henceforth leave things in a
  * state where many or all calls fail).
  */
-_hidden void libxl__event_disaster(libxl__egc*, const char *msg, int errnoval,
+_hidden void libxl__event_disaster(libxl__gc*, const char *msg, int errnoval,
                                    libxl_event_type type /* may be 0 */,
                                    const char *file, int line,
                                    const char *func);
-#define LIBXL__EVENT_DISASTER(egc, msg, errnoval, type) \
-    libxl__event_disaster(egc, msg, errnoval, type, __FILE__,__LINE__,__func__)
+#define LIBXL__EVENT_DISASTER(gc, msg, errnoval, type) \
+    libxl__event_disaster(gc, msg, errnoval, type, __FILE__,__LINE__,__func__)
 
 
 /* Fills in, or disposes of, the resources held by, a poller whose