libxl: init: libxl__poller_init and _get take gc

Change libxl__poller_init and libxl__poller__get to take a libxl__gc*
rather than a libxl_ctx*.  The gc is not used for memory allocation
but simply to provide the standard local variable "gc" expected by the
convenience macros.  Doing this makes the error logging more
convenient.

Hence, convert the logging calls to use the LOG* convenience macros.

And consequently, change the call sites, and the function bodies to
use CTX rather than ctx.

Also convert a call to malloc() (with error check) in
libxl__poller_get, to libxl__zalloc (no error check needed).

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
CC: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

tools/libxl/libxl.c

@@ -87,7 +87,7 @@ int libxl_ctx_alloc(libxl_ctx **pctx, int version,
     rc = libxl__atfork_init(ctx);
     if (rc) goto out;
 
-    rc = libxl__poller_init(ctx, &ctx->poller_app);
+    rc = libxl__poller_init(gc, &ctx->poller_app);
     if (rc) goto out;
 
     ctx->xch = xc_interface_open(lg,lg,0);

tools/libxl/libxl_event.c

@@ -1347,13 +1347,13 @@ int libxl__self_pipe_eatall(int fd)
  * Manipulation of pollers
  */
 
-int libxl__poller_init(libxl_ctx *ctx, libxl__poller *p)
+int libxl__poller_init(libxl__gc *gc, libxl__poller *p)
 {
     int rc;
     p->fd_polls = 0;
     p->fd_rindices = 0;
 
-    rc = libxl__pipe_nonblock(ctx, p->wakeup_pipe);
+    rc = libxl__pipe_nonblock(CTX, p->wakeup_pipe);
     if (rc) goto out;
 
     return 0;
@@ -1370,25 +1370,20 @@ void libxl__poller_dispose(libxl__poller *p)
     free(p->fd_rindices);
 }
 
-libxl__poller *libxl__poller_get(libxl_ctx *ctx)
+libxl__poller *libxl__poller_get(libxl__gc *gc)
 {
     /* must be called with ctx locked */
     int rc;
 
-    libxl__poller *p = LIBXL_LIST_FIRST(&ctx->pollers_idle);
+    libxl__poller *p = LIBXL_LIST_FIRST(&CTX->pollers_idle);
     if (p) {
         LIBXL_LIST_REMOVE(p, entry);
         return p;
     }
 
-    p = malloc(sizeof(*p));
-    if (!p) {
-        LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "cannot allocate poller");
-        return 0;
-    }
-    memset(p, 0, sizeof(*p));
+    p = libxl__zalloc(NOGC, sizeof(*p));
 
-    rc = libxl__poller_init(ctx, p);
+    rc = libxl__poller_init(gc, p);
     if (rc) {
         free(p);
         return NULL;
@@ -1477,7 +1472,7 @@ int libxl_event_wait(libxl_ctx *ctx, libxl_event **event_r,
     EGC_INIT(ctx);
     CTX_LOCK;
 
-    poller = libxl__poller_get(ctx);
+    poller = libxl__poller_get(gc);
     if (!poller) { rc = ERROR_FAIL; goto out; }
 
     for (;;) {
@@ -1653,7 +1648,7 @@ libxl__ao *libxl__ao_create(libxl_ctx *ctx, uint32_t domid,
     if (how) {
         ao->how = *how;
     } else {
-        ao->poller = libxl__poller_get(ctx);
+        ao->poller = libxl__poller_get(&ao->gc);
         if (!ao->poller) goto out;
     }
     libxl__log(ctx,XTL_DEBUG,-1,file,line,func,

tools/libxl/libxl_internal.h

@@ -834,13 +834,13 @@ _hidden void libxl__event_disaster(libxl__egc*, const char *msg, int errnoval,
 
 /* Fills in, or disposes of, the resources held by, a poller whose
  * space the caller has allocated.  ctx must be locked. */
-_hidden int libxl__poller_init(libxl_ctx *ctx, libxl__poller *p);
+_hidden int libxl__poller_init(libxl__gc *gc, libxl__poller *p);
 _hidden void libxl__poller_dispose(libxl__poller *p);
 
 /* Obtain a fresh poller from malloc or the idle list, and put it
  * away again afterwards.  _get can fail, returning NULL.
  * ctx must be locked. */
-_hidden libxl__poller *libxl__poller_get(libxl_ctx *ctx);
+_hidden libxl__poller *libxl__poller_get(libxl__gc *gc);
 _hidden void libxl__poller_put(libxl_ctx*, libxl__poller *p /* may be NULL */);
 
 /* Notifies whoever is polling using p that they should wake up.